POL 12B

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What do we mean by climate sensitivity?

How much the climate changes in response to a given RF : It is a measure of how sensitive the climate system is to changes in radiative forcing, which includes greenhouse gas concentrations, solar radiation, and other factors that influence the Earth's energy balance. In more specific terms, climate sensitivity is often expressed as the change in temperature (usually in degrees Celsius) that would occur when the atmospheric CO2 concentration doubles, while other factors are held constant. This measure helps scientists understand the potential consequences of increased greenhouse gas emissions and the resulting global warming.

Quiz 3 : One component of the IPAT identity is energy intensity (EI). Which of the following constitutes a reduction in energy intensity? a) Transitioning from coal-fired power plants to solar electricity generation b) Replacing your incandescent light bulbs with LED bulbs

b) Replacing your incandescent light bulbs with LED bulbs option a would be more carbon intensity related

Quiz 2 : What is the main way humans have changed Earth's carbon cycle? a) We've transferred carbon from the land biosphere to the atmosphere b) We've transferred carbon from the oceans to the atmosphere c) We've transferred carbon from the rock reservoir to the atmosphere d) All of the above

c) We've transferred carbon from the rock reservoir to the atmosphere

Quiz 2 : Consider the following equation for a planet's equilibrium temperature (T): T = ∜ ((n+1) s (1-a)) / (4a) Which of the following changes would cool the planet? (Note: a is expressed as "alpha" below.) a) An increase in n b) An increase in S c) An increase in alpha d) All of the above e) None of the above

c) an increase in alpha

Quiz 1 : In 2023, California and Vermont were deluged with heavy rain, ocean temperature records were broken in Florida, and much of the US experienced extreme heat waves. These are all examples of a) climate b) Weather

weather

Quiz 1 : The 2020s have (so far) been hotter than the 2010s, which were hotter than the 2000s, which were hotter than the 1990s, and so on. This trend points to changes in a) Climate b) weather

Climate

What is climate change?

Climate change: Any systematic change in the long-term statistics of climate elements (such as temperature, pressure, or winds)sustained over several decades or longer.

Quiz 3 : Which of the following is NOT an example of climate adaptation? a) Elevating your home to protect it from floods b) Installing rooftop solar panels to reduce your carbon emissions c) Installing air conditioning to survive heat waves d) Buying fire and flood insurance

b) Installing rooftop solar panels to reduce your carbon emissions

Quiz 3 : One component of the IPAT identity is carbon intensity (CI). Which of the following constitutes a reduction in carbon intensity? a) Replacing your gas-guzzling car with a more fuel-efficient one (that still burns gas) b) Replacing your gas-guzzling car with an electric one powered by solar and wind energy

b) Replacing your gas-guzzling car with an electric one powered by solar and wind energy

Quiz 3 : Which of the following is an abrupt climate impact? a) Rising sea levels b) Increased precipitation c) A shutdown of the Atlantic Meridional Overturning Circulation (AMOC) d) A loss of biodiversity

c) A shutdown of the Atlantic Meridional Overturning Circulation (AMOC)

Which of the following would lead to positive radiative forcing? a) "Energy In" increases by 10 while "Energy Out" increases by 5 b) "Energy In" decreases by 5 while "Energy Out" decreases by 10 "Energy In" increases by 5 while "Energy Out" decreases by 5 c) All of the above d) None of the above

"Energy In" increases by 10 while "Energy Out" increases by 5: Δ(Energy In) = +10 Δ(Energy Out) = +5 Δ(Energy In) - Δ(Energy Out) = +10 - (+5) = +10 - 5 = +5 This scenario results in a net increase in energy retained by the planet, which leads to positive radiative forcing. "Energy In" decreases by 5 while "Energy Out" decreases by 10: Δ(Energy In) = -5 Δ(Energy Out) = -10 Δ(Energy In) - Δ(Energy Out) = -5 - (-10) = -5 + 10 = +5 This scenario also results in a net increase in energy retained by the planet, which leads to positive radiative forcing. "Energy In" increases by 5 while "Energy Out" decreases by 5: Δ(Energy In) = +5 Δ(Energy Out) = -5 Δ(Energy In) - Δ(Energy Out) = +5 - (-5) = +5 + 5 = +10 This scenario results in a larger net increase in energy retained by the planet, which leads to positive radiative forcing. Therefore, all of the given scenarios lead to positive radiative forcing.

Quiz 1 : Under which of the following conditions should we expect a planet's temperature to RISE? a) Energy in < Energy out b) Energy in = Energy out c) Energy in > Energy out d) All of the above e) None of the above

c) Energy in > Energy out

What does adding another atmosphere do?

Each layer of the atmosphere adds another level of greenhouse effect, making it increasingly effective at keeping the planet's surface warm. This is analogous to wearing additional layers of clothing on a cold day, where each layer traps more heat and keeps you warmer. The atmosphere, acting as a "planetary jacket," retains heat and warms the planet by preventing the escape of infrared radiation into space.

What are some alternative (i.e., non-anthropogenic) explanations for recent climate change? Why are these explanations unconvincing?

1. **Plate Tectonics**: Plate tectonics operate on slow timescales, requiring millions of years to produce significant changes in climate. Recent climate change has occurred over a much shorter timeframe, making plate tectonics an unsuitable explanation. 2. **The Sun**: : : over its 5-billion-year life, the Sun has become ~30% brighter BUT - there is no evidence that solar radiation has changed appreciably over the last few centuries. Moreover, solar activity has been relatively stable during the period of rapid warming, suggesting that the Sun is not responsible for recent temperature increases. 3. **Earth's Orbit and Orientation**: Changes in Earth's orbit influenced past climate variations, such as ice-age cycles. However, these changes occur very slowly, requiring tens of thousands of years to impact climate significantly. They cannot account for the recent rapid warming observed. UNFORCED VARIABILITY : SLIDE 32 - LECTURE 3 ; thin el nino ------models without human caused increase

What is a blackbody? How is a blackbody's temperature related to the power it emits?

A blackbody is an idealized construct that absorbs photons but does not reflect any In other words, it is an object that appears completely black because it absorbs all incident light and emits radiation according to its temperature. The key takeaway is that as the temperature of a blackbody increases, it emits more energy per unit area and over a broader range of wavelengths. This is why hotter objects, such as incandescent light bulbs or very hot stars, produce more visible photons and appear brighter. all objects with temperatures above absolute zero (0 Kelvin) emit thermal radiation, including humans and the Earth. However, the type of radiation they emit is determined by their temperature

What is carbon dioxide removal?

Carbon Dioxide Removal (CDR) refers to the process of actively removing carbon dioxide (CO2) from the Earth's atmosphere to mitigate the impacts of climate change

How have emissions of carbon dioxide, methane, and sulfate aerosols affected the Earth's RF?

Co2 : Positive RF: The increase in CO2 emissions from human activities, such as burning fossil fuels and deforestation, results in a positive RF because CO2 is a greenhouse gas. Greenhouse gases, like CO2, have the ability to absorb and re-emit infrared radiation. As CO2 concentrations rise in the atmosphere, more heat is trapped, leading to a net increase in RF. This enhanced greenhouse effect contributes to global warming and higher temperatures. Methane : Positive RF: Methane emissions have a positive RF because methane is a powerful greenhouse gas. On a per-molecule basis, it has a much greater heat-trapping potential than CO2. When methane is released into the atmosphere from sources like livestock, rice paddies, and the petrochemical industry, it contributes to the enhanced greenhouse effect, trapping more heat and causing a positive RF. While methane has a shorter atmospheric lifetime than CO2, its immediate warming impact is substantial. Sulfate Aerosols: Negative RF: Sulfate aerosols have a negative RF because they are reflective particles. These aerosols are released into the atmosphere when fossil fuels, especially coal, are burned. Unlike greenhouse gases, sulfate aerosols reflect incoming solar radiation back into space, which has a cooling effect on the climate. This counteracts some of the warming caused by greenhouse gases. As a result, sulfate aerosols lead to a negative RF, contributing to a cooling effect. In summary, the effects of these emissions on Earth's RFterm-44 are driven by their properties and interactions with incoming and outgoing radiation. CO2 and methane act as heat-trapping greenhouse gases, leading to positive RF and contributing to global warming. In contrast, sulfate aerosols, by reflecting sunlight, have a cooling effect on the climate, resulting in a negative RF. These interactions play a crucial role in shaping the Earth's climate and temperature trends.

Under what conditions will Earth's climate stabilize? What could we do to bring this about?

Earth's climate will stabilize when the radiative forcing (RF) reaches a balance of zero. This means that the energy entering the Earth's climate system (Ein) is equal to the energy leaving it (Eout). NOTE : To stabilize the climate we need (net) zero emissions; to reverse climate change we need (net) negative emissions Zero Radiative Forcing (RF): The primary condition is that the radiative forcing must be reduced to zero. RF is currently positive, contributing to global warming. To stabilize the climate, we must eliminate this positive RF. 2. Reducing Ein: One way to achieve zero RF is to reduce the energy entering the Earth's climate system. This could be done through solar radiation management (SRM) techniques, which aim to reflect some of the incoming sunlight back into space, effectively reducing Ein. 3. Increasing Eout: Another way to reach zero RF is by increasing the energy leaving the Earth's climate system. This can be accomplished by reducing the concentration of greenhouse gases (GHGs) in the atmosphere, particularly carbon dioxide (CO2). By doing so, we can enhance the planet's ability to emit more energy (Eout) into space. It's essential to note that simply reducing GHG emissions is not sufficient to stabilize the climate. While emissions reductions can slow the rate of global warming, they do not lead to zero RF. Achieving climate stabilization and reversing climate change require achieving net-zero emissions, where the amount of GHGs removed from the atmosphere equals the amount emitted. Solutions? 1. Reducing GHG Emissions: Efforts must continue to reduce GHG emissions from various sources, such as fossil fuel combustion, deforestation, and land-use changes. Transitioning to renewable energy sources, improving energy efficiency, and adopting sustainable land management practices are essential steps. 2. Carbon Removal: Beyond emissions reductions, active carbon removal technologies can be used: afforestation and reforestation, carbon capture and storage (CCS), and direct air capture. 3. Solar Radiation Management : These methods involve reflecting sunlight away from the Earth, effectively reducing Ein.

How have humans perturbed the carbon cycle? How has this affected our atmosphere?

Humans have significantly perturbed the carbon cycle by transferring carbon from the Earth's rock reservoir into the atmosphere at an accelerated rate, primarily through the combustion of fossil fuels. 1. Combustion of Fossil Fuels: The burning of fossil fuels, including coal, oil, and natural gas, for energy production and various industrial processes, releases large quantities of carbon dioxide (CO2) into the atmosphere. Fossil fuels contain carbon that was sequestered underground over millions of years. When humans extract and burn these fuels, the carbon stored in them is rapidly released into the atmosphere. 2. Rapid Transfer of Carbon: Natural processes, such as volcanic eruptions and chemical weathering, also transfer carbon between the rock reservoir and the atmosphere. However, the rate of carbon transfer from fossil fuel combustion is approximately 100 times faster than these natural processes. This rapid transfer has led to a substantial increase in atmospheric CO2 concentrations. 3. Increased Atmospheric CO2: The release of CO2 from fossil fuel combustion has significantly elevated the concentration of carbon dioxide in the atmosphere. The current atmospheric CO2 level is approximately 0.0412% (412 parts per million or ppm), up from pre-industrial levels of around 280 ppm. This increase in atmospheric CO2 is a direct result of human activities. 4. Enhanced Greenhouse Effect: CO2 is a potent greenhouse gas that traps heat in the Earth's atmosphere. The higher concentration of CO2 has intensified the natural greenhouse effect, leading to global warming and climate change. This warming effect is a result of the enhanced trapping of heat, which has led to rising global temperatures, altered weather patterns, and other climate-related impacts. 5. Climate Change: The perturbation of the carbon cycle by human activities has caused a wide range of climate change effects, including rising global temperatures, more frequent and severe heatwaves, changing precipitation patterns, melting ice caps and glaciers, and rising sea levels. These changes have significant and far-reaching consequences for ecosystems, agriculture, water resources, and human societies.

Quiz 2 : In Dessler's one-layer climate model, the Earth's atmosphere is a) transparent to visible photons but non-transparent to infrared photons b) transparent to infrared photons but non-transparent to visible photons c) transparent to both visible and infrared photons d) non-transparent to both visible and infrared photons

a) transparent to visible photons but non-transparent to infrared photons

What are two common concerns about "geoengineering" policies? What responses to these concerns did we discuss in class?

Moral Hazard: The concern that geoengineering may reduce the incentives to cut greenhouse gas (GHG) emissions. In other words, if people believe that geoengineering can offset the impacts of GHG emissions, they might be less motivated to reduce their emissions. This could lead to a continued or even increased reliance on fossil fuels and other activities that contribute to climate change. Response: While moral hazard is a valid concern, it's important to note that other policies, such as insurance or disaster relief, also carry moral hazard risks. These policies are still chosen because they provide a safety net for unforeseen circumstances. In the case of geoengineering, the response is to carefully design and regulate these technologies to ensure they are used as a complement to emission reduction efforts, not a replacement. We Shouldn't Play God: Some people argue that geoengineering interventions are unnatural and that humans should not tamper with the Earth's climate systems. They see it as an ethical or moral objection to intentionally altering the environment. Response: The counterargument to this concern is that humans have already significantly altered the Earth's environment and climate through various activities, including urbanization, deforestation, agriculture, and GHG emissions. Geoengineering can be seen as a way to mitigate the damage caused by these existing interventions. Rather than "playing God," it can be viewed as a responsible approach to address the consequences of human activities. It's also important to conduct thorough cost-benefit analyses and ensure responsible governance to address these concerns. In summary, while mitigation (reducing GHG emissions) remains the primary approach to addressing climate change, geoengineering policies like SRM and CDR are considered as additional tools to mitigate and adapt to climate change. The key is to use these technologies responsibly and in conjunction with emission reduction efforts to achieve the most effective and ethical outcomes.

What are some safeguards against individually flawed studies?

Peer Review: The peer-review process is a fundamental safeguard in scientific research. Before a study is published in a reputable journal, it undergoes scrutiny by independent experts in the field who evaluate the study's methodology, data analysis, and conclusions. This helps identify and address potential flaws. Replication: Replicating studies by independent researchers is a powerful way to validate or refute findings. If a study's results can be consistently reproduced, it adds to the credibility of the research. Journals and funding agencies are increasingly encouraging replication studies. Transparency and Open Data: Researchers are encouraged to be transparent about their methods and to share their data and code whenever possible. Transparency allows other researchers to assess the study's quality and reproduce its results. Publication Ethics: Journals and publishers have guidelines and codes of ethics that authors must adhere to. These guidelines help maintain the quality and integrity of published research.

What, in general, are mitigation policies? What parameters in the IPAT identity do they seek to influence? Answered on a diff flash card : What kinds of broad changes do these policies need to bring about?

Population (P): Mitigation policies do not directly focus on population control but rather on how technology and practices can be adapted to accommodate a growing population more sustainably. For example, they promote energy-efficient technologies in housing and transportation to reduce emissions per capita. Affluence (A): Mitigation policies aim to decouple economic growth from emissions. They encourage the development and adoption of cleaner technologies, energy efficiency measures, and sustainable practices to ensure that increased affluence does not lead to proportionally higher emissions. Technology (T): This is the central focus of mitigation policies. They seek to transform technology and infrastructure to reduce carbon intensity. Key elements of technology-driven mitigation policies include transitioning to clean electricity generation, electrifying sectors such as transportation and heating, and finding substitutes or reducing the use of emissions-intensive technologies.

What is radiative forcing (RF)? What are the consequences of positive and negative RF, respectively?

RF = quantifies the change in the energy balance of the Earth's climate system. It measures the difference between the energy received by the Earth from incoming sunlight (Ein) and the energy radiated back into space (Eout) due to changes in external factors, such as human activities or natural processes. RF = Δ(Ein - Eout) = ΔEin - ΔEout Positive Radiative Forcing (+RF): Positive radiative forcing implies that the Earth's energy balance is shifted in favor of warming. In other words, more energy is being retained within the Earth's climate system than is being radiated back into space. Consequences of positive RF include:An increase in global temperatures: The retained energy leads to a rise in the Earth's average surface temperature.Acceleration of the greenhouse effect: Positive RF is often associated with increased concentrations of greenhouse gases, such as carbon dioxide and methane, which trap more heat in the atmosphere.Climate impacts: Positive RF can result in various climate-related effects, including more frequent and severe heatwaves, sea level rise, changes in precipitation patterns, and shifts in ecosystems. Negative Radiative Forcing (-RF): Negative radiative forcing implies that the Earth's energy balance is shifted in favor of cooling. More energy is radiated back into space than is being absorbed by the planet. Consequences of negative RF include:Cooling of the Earth's surface: The loss of energy from the Earth results in lower surface temperatures.Potential offset of warming: Negative RF can partially offset the warming effects caused by positive RF. For example, the presence of aerosols in the atmosphere, which reflect sunlight back into space, contributes to negative RF and can have a cooling effect. Radiative forcing is an essential concept for understanding how changes in external factors, particularly human activities like the burning of fossil fuels and deforestation, influence the Earth's climate. Positive RF is a key driver of global warming and climate change, while negative RF can mitigate some of the warming, although it may have its own environmental and health consequences fro, air pollution from aerosols.

Why do we pay so much attention to CO2 from fossil fuels when plants and animals emit far more CO2 to the atmosphere?

Seasonal Changes vs. Long-Term Increase: The primary distinction is that emissions from plants and animals, including natural respiration, follow a seasonal cycle. During the growing season, plants take up CO2 from the atmosphere through photosynthesis, effectively removing CO2. However, in the non-growing season, or when plants and animals respire, they release CO2 back into the atmosphere. This cycle results in short-term fluctuations in atmospheric CO2 levels but does not lead to a sustained, long-term increase. Fossil Fuels Release Ancient Carbon: In contrast, when we burn fossil fuels, we release CO2 that was sequestered in the Earth's crust for millions of years. This carbon, which had been safely locked away, is being returned to the atmosphere in a relatively short period. This process results in a net addition of CO2 to the atmosphere over the long term. The carbon released from fossil fuel combustion is radiocarbon dead, indicating its ancient origin and the fact that it has not been part of the natural carbon cycle for a very long time. In summary, the key difference is the timescale and the net effect. Natural respiration and the carbon emissions from plants and animals are part of the natural carbon cycle, with emissions and removals that largely balance each other over relatively short timescales (e.g., seasons). These natural processes do not cause a long-term increase in atmospheric CO2. On the other hand, fossil fuel combustion releases carbon that has been sequestered for millions of years, contributing to a net, long-term increase in atmospheric CO2 levels. This additional CO2 traps heat in the Earth's atmosphere, intensifies the greenhouse effect, and drives global warming, which leads to various climate change impacts. Hence, the focus on CO2 from fossil fuels is due to its capacity to drive long-term changes in atmospheric CO2 concentrations and its central role in contemporary climate change.

Sulfate - aerosol trade offs

Sulfate aerosols present several trade-offs in their effects on the Earth's climate and environment. Here are some of the key trade-offs: **1. Cooling the Planet vs. Health and Environmental Impacts**: - *Cooling Effect*: Sulfate aerosols have a cooling effect on the climate by reflecting sunlight and increasing the Earth's albedo. This can help offset some of the warming caused by greenhouse gases. - *Health and Environmental Impact*: Sulfur pollution, which leads to the formation of sulfate aerosols, is harmful to human health and the environment. It can irritate the respiratory tract, contribute to acid rain, deforestation, and water acidification. **2. Climate Mitigation vs. Air Quality Improvement**: - *Climate Mitigation*: Sulfate aerosols have been proposed as a form of solar radiation management (SRM) to deliberately cool the Earth. This suggests that intentionally releasing sulfate aerosols into the atmosphere could be a tool for mitigating the impacts of climate change. - *Air Quality Improvement*: On the other hand, reducing sulfur pollution, which is a precursor to sulfate aerosols, is a priority for improving air quality and public health. This includes measures to reduce emissions from industrial and transportation sources. **3. Global vs. Local Effects**: - *Global Climate Effects*: Sulfate aerosols have a global cooling effect by reflecting sunlight. The cooling is spread over a large area, affecting global climate patterns. - *Local Air Quality Effects*: Sulfur pollution has localized effects on air quality, particularly in urban areas near emission sources. Reductions in sulfur dioxide emissions can lead to immediate improvements in local air quality. **4. Short-Term vs. Long-Term Impact**: - *Short-Term Cooling*: Sulfate aerosols have a relatively short-term cooling impact, especially in the case of volcanic eruptions where their effects can last for a few years. - *Long-Term Climate Mitigation*: The long-term impact of sulfate aerosols on global climate is uncertain. Using sulfate aerosols as a deliberate climate mitigation strategy may have long-lasting consequences. In summary, sulfate aerosols have both beneficial and detrimental effects. They can cool the planet

What are the main components of the carbon cycle?

The carbon cycle is a fundamental Earth system process that involves the movement of carbon (in various forms) between different reservoirs, primarily the atmosphere, land biosphere, ocean, and rock reservoirs. Here's how carbon moves between these components: - Atmosphere (Contains a portion of Earth's carbon, primarily in the form of carbon dioxide (CO2)) - Land Biosphere : Land biosphere includes forests, vegetation, and soil. Plants absorb CO2 from the atmosphere during photosynthesis, converting it into organic carbon. When plants and animals respire or decompose, carbon is released back into the atmosphere as CO2. This is a continuous cycle in the land biosphere. Ocean = vast carbon reservoirs. CO2 dissolves in water and forms carbonic acid, contributing to the ocean's dissolved inorganic carbon pool. This process helps regulate atmospheric CO2 levels. The oceans also absorb and release carbon through physical and biological processes, such as the biological pump, which transports organic carbon from the surface to deeper layers. Rock Reservoir = ir: Large amounts of carbon are stored in rocks, including limestone (calcium carbonate). The exchange between rocks and the atmosphere is much slower than other components of the carbon cycle. Volcanic eruptions release carbon into the atmosphere, and chemical weathering of rocks removes CO2 from the atmosphere, gradually transferring it to the rock reservoir. This process occurs over geological timescales.

What kinds of climatic changes have we observed over the Earth's history? How does this compare with the record of the last ~11,000 years? ANswer to this in another card : Why are the relatively small recent changes nonetheless cause for concern?

The observed climatic changes over Earth's history provide crucial context for understanding the significance of recent changes and why they are cause for concern. Here's how the historical climate variations compare to the recent past and why contemporary climate change is a matter of great concern: 1. **Long-Term Climate Variability**: - Over hundreds of thousands of years, Earth's climate has experienced substantial fluctuations, with temperature variations of up to 10 degrees Celsius. These changes are primarily driven by natural factors such as changes in Earth's orbit and volcanic activity. 2. **Holocene Period (Last ~11,000 Years)**: - In the last 12,000 years, the Earth's climate has been relatively stable, with temperature variations of less than 1 degree Celsius. This period, known as the Holocene, has been characterized by a relatively mild and stable climate. 3. **Recent Climate Changes**: - Over the last 2,000 years, until recently, the Earth's climate remained within an even narrower temperature range. However, in recent decades, global temperatures have been increasing at an accelerated rate due to human activities, primarily the emission of greenhouse gases. 4. **Comparison to Past Changes**: - While the Earth has experienced significant temperature fluctuations in its geological history, including ice ages that were much colder than today, the concern arises from the speed and extent of the current changes. A few degrees Celsius of global warming, which we are currently on track to reach, can bring about radical environmental shifts. 5. **Human Civilization Adaptation**: - Human civilization, including settlement patterns, infrastructure, and agriculture, has developed and adapted to the stable climate of the Holocene. Abrupt climate changes can disrupt these systems and have serious implications for food security, water resources, and infrastructure.

How does our "choice" of SSP affect our medium-term climate future (e.g., the next 20 years)? How does it affect our long-term future (e.g., the next 80, 200 or 1,000 years)?

look at slide 32 for reference of lecture 4 In the next 20 years, there will not be huge differences, but in the next 10000, there will be huge differences! Medium-Term Climate Future (Next 20 Years): Emissions Trajectory: SSPs with higher emissions scenarios will lead to more rapid increases in atmospheric CO2 concentrations, contributing to higher temperatures and more immediate climate impacts. Temperature Projections:SSPs with higher emissions may lead to faster warming over the next 20 years, resulting in more frequent and severe extreme weather events, such as heatwaves, droughts, and heavy precipitation. Adaptation and Mitigation Strategies: The choice of SSP has implications for the urgency of implementing climate adaptation and mitigation strategies. SSPs with lower emissions scenarios provide more time to adapt to changing conditions and reduce emissions, whereas high-emissions scenarios require immediate and aggressive actions to mitigate their impacts. LONG TERM Cumulative Emissions: High-emissions SSPs result in a continuous rise in emissions, contributing to a substantial increase in atmospheric CO2 levels over the next century. Temperature Trajectory: High-emissions SSPs lead to more pronounced and sustained warming, with temperature increases continuing for centuries. Climate Impacts: High-emissions SSPs result in more severe and irreversible effects, such as accelerated sea-level rise, more frequent and intense extreme weather events, and prolonged heatwaves. Tipping Points and Irreversible Changes: Some climate-related events, such as the disintegration of ice sheets or the shutdown of ocean circulation systems, are considered tipping points. The choice of SSP affects the likelihood and timing of reaching these tipping points, which can have irreversible and catastrophic consequences for the climate system. Biodiversity and Ecosystems: The choice of SSP also affects biodiversity and ecosystems over the long term. High-emissions scenarios may lead to widespread species extinction and ecosystem collapse, disrupting ecological systems and causing ecological imbalances.

What do we mean by "climate feedbacks"? Do they tend (on average) to be positive or negative?

Climate feedbacks refer to processes in the Earth's climate system that either amplify or dampen the initial climate change caused by an external forcing, such as increased greenhouse gas concentrations. These feedback mechanisms can either enhance or counteract the primary response, influencing the overall climate sensitivity and the extent of global warming. On average, climate feedbacks tend to be positive, meaning they amplify the initial climate change. This is a crucial aspect of climate science because positive feedbacks can lead to more significant and rapid changes in temperature and other climate variables.

How do we know fossil fuels are causing the increase in atmospheric CO2, rather than natural sources such as volcanoes or plants?

Correlation between Human Emissions and Atmospheric CO2 Increase: For several decades, there has been a strong correlation between the increase in atmospheric CO2 levels and human emissions of CO2. The fact that the increase in atmospheric CO2 closely matches human emissions suggests that human activities are the dominant source of this increase. - the increase in atmospheric CO2 has closely tracked the pattern of human CO2 emissions. The rate of increase in CO2 concentrations in the atmosphere matches the rate at which CO2 is being released by human activities. Radiocarbon Dating: CO2 in the atmosphere can be chemically "fingerprinted" using radiocarbon dating. Radiocarbon dating can determine the age of carbon-containing materials, and it works based on the radioactive isotope carbon-14 (C-14). Fossil fuels, such as coal, oil, and natural gas, are derived from ancient plant and animal matter that has been sequestered underground for millions of years. As a result, the carbon in fossil fuels is "radiocarbon dead," meaning it has no carbon-14 left. In contrast, contemporary plant material, which makes up a significant portion of the natural carbon cycle, contains carbon-14. The fact that the CO2 being added to the atmosphere is radiocarbon dead indicates that it comes from the burning of fossil fuels, which release carbon that was sequestered millions of years ago. - The absence of C-14 in most atmospheric CO2 is a clear indicator that this carbon comes from the combustion of fossil fuels, confirming that human activities are responsible for the rise in atmospheric CO2 levels. Seasonal Changes vs. Long-Term Increase: he primary distinction is that emissions from plants and animals, including natural respiration, follow a seasonal cycle. During the growing season, plants take up CO2 from the atmosphere through photosynthesis, effectively removing CO2. However, in the non-growing season, or when plants and animals respire, they release CO2 back into the atmosphere. This cycle results in short-term fluctuations in atmospheric CO2 levels but does not lead to a sustained, long-term increase.

Why are anthropogenic GHGs a better explanation? compared to others?

In contrast, the GHG hypothesis is a more convincing explanation for recent climate change for several reasons: Robust Theory: The link between greenhouse gases and global warming is based on well-established physics, dating back to the work of Svante Arrhenius in 1896. The greenhouse effect is a fundamental aspect of Earth's climate system. Empirical Support: The correlation between increasing GHG concentrations and rising global temperatures is supported by a wealth of observational data. This includes the instrumental record of temperature measurements, the geological record, and proxy data. Climate Models: Climate models that incorporate GHG forcings successfully replicate observed climate changes, both retrospectively and prospectively. Models that exclude radiative forcing from GHGs fail to reproduce observed warming trends. Consistency with Other Climate Fingerprints: The GHG hypothesis aligns with various other "fingerprints" of climate change, such as the observed decrease in stratospheric temperatures and changes in the diurnal temperature range. In summary, while alternative explanations have been considered, none of them offer as strong a theoretical and empirical basis as the role of anthropogenic greenhouse gases. The overwhelming consensus among climate scientists is that human activities, particularly the emission of GHGs, are the primary driver of recent global warming. This conclusion is based on the robustness and consistency of the evidence supporting the GHG hypothesis.

What does the IPAT identity tell us? How does it help forecast future emissions? How does it point us toward climate solutions? In answering these questions, be sure to remember that T can be further decomposed.

I represents environmental impact. P stands for population. A represents affluence (often measured as per capita income or consumption). T represents technology (the level of technology or the efficiency of processes). The IPAT equation emphasizes that both the number of people (population) and their consumption patterns (affluence) play crucial roles in determining the total environmental impact. The level of technology (T) used to produce and consume goods and services also contributes to environmental outcomes. Forecast of future emissions: Population growth projections can inform us about potential increases in energy and resource consumption. Changes in affluence can help us predict shifts in consumption patterns and energy use. Advancements in technology can influence energy efficiency and emissions reductions. Population Management: Stabilizing or reducing population growth through family planning and reproductive health programs can help limit the overall impact on the environment. Affluence and Consumption: Promoting sustainable consumption patterns and reducing overconsumption, especially in affluent societies, can lower environmental impact. Technology and Innovation: Developing and adopting cleaner and more energy-efficient technologies is a key strategy for reducing emissions. Investments in research and development, as well as policies that encourage technological innovation, play a crucial role. Decomposing "T": The T factor can be further decomposed into energy intensity (energy use per unit of GDP) and carbon intensity (carbon emissions per unit of energy use). By improving energy efficiency and transitioning to low-carbon technologies, we can significantly reduce carbon emissions. Policy and Regulation: Governments, businesses, and organizations can implement policies and regulations that promote sustainability and reduce emissions. These can include carbon pricing, renewable energy incentives, emission reduction targets, and environmental standards. In summary, the IPAT identity helps us understand the complex relationship between human activities and environmental impact, particularly in the context of greenhouse gas emissions. By decomposing the factors contributing to environmental im

Let's say we add an atmospheric "layer" by adding GHGs to the atmosphere. Will the Earth warm instantly in response? Why or why not?

No - due to climate sensitivity - Climate sensitivity refers to how much the Earth's average temperature responds to changes in the radiative forcing, which is the difference between the energy received from the Sun and the energy radiated back into space. Thermal Inertia: The Earth's climate system has thermal inertia, which means it takes time to respond to changes in the energy balance. Just like it takes time for a pot of water to heat up on a stove, the Earth's climate system has a lag in its response to changes in radiative forcing. The ocean, in particular, has a large heat capacity and can absorb and store heat, causing a delay in temperature increases. Feedback Mechanisms: Climate sensitivity is influenced by feedback mechanisms. These are processes that can either amplify or dampen the initial temperature change. For example, as the Earth warms due to increased GHGs, it can lead to feedbacks like reduced snow and ice cover, which further amplify warming. These feedbacks take time to develop and influence the overall response. Long-Term Equilibrium: The full response of the climate system to increased GHGs occurs over centuries to millennia. While there is an initial, relatively rapid temperature increase, reaching long-term equilibrium, where the Earth's surface temperature stabilizes at a new level, takes a long time. In summary, the Earth's climate system does not respond instantly to changes in GHG concentrations. Instead, there is a lag due to thermal inertia and the time it takes for feedback mechanisms to fully manifest. While there is an initial temperature increase, the complete response to increased GHGs occurs over an extended period, making it essential to take early action to mitigate climate change, as the consequences of our actions today will have long-lasting effects on future climate.

A dog, the Earth, a lightbulb and the Sun all emit radiation. Why do only some of these objects seem to "glow"?

Objects appear to "glow" or emit visible light when they reach a high enough temperature to radiate in the visible part of the electromagnetic spectrum. This phenomenon is described by Planck's law of black-body radiation, and it's related to an object's temperature and its ability to emit light at different wavelengths. Let's look at the objects you mentioned: 1. **The Sun**: The Sun is extremely hot, with its core temperature reaching millions of degrees Celsius. Because of its high temperature, it emits a substantial amount of visible light along with other electromagnetic radiation. This visible light is what we perceive as sunlight, and it's why the Sun appears to glow. 2. **A Lightbulb**: A typical incandescent lightbulb also works based on the principle of heating a filament to a high temperature. The filament gets so hot that it emits visible light, making the bulb glow. 3. **Earth**: Earth doesn't appear to glow in the visible spectrum because its temperature is much lower than that of the Sun or a lightbulb. Earth mainly emits infrared radiation due to its relatively cooler temperature. While it does reflect some sunlight, this reflection is not perceived as Earth "glowing." 4. **A Dog**: A dog, like all objects with a temperature above absolute zero, emits thermal radiation, which includes infrared radiation. However, because a dog's body temperature is still relatively low compared to the Sun or a lightbulb, the amount of visible light it emits is negligible. Thus, it doesn't appear to glow in the visible spectrum. In summary, the concept of "glowing" in the visible spectrum is primarily related to an object's temperature. Extremely high temperatures, like those found in the Sun or a hot filament in a lightbulb, lead to the emission of visible light. Objects with lower temperatures, such as the Earth and a dog, primarily emit radiation in the infrared range, making them appear dark or not glowing in the visible spectrum.

What is an SSP? How are SSPs constructed, i.e., what is assumed?

Shared Socioeconomic Pathways (SSPs) are a set of scenarios that climate researchers and scientists use to explore and model different potential futures for global socioeconomic development. These pathways help in assessing the possible outcomes of climate change by considering various combinations of population (P), GDP per capita (A), and carbon intensity (T) trends. Construction of SSPs: Trends in Population (P): SSPs consider different demographic transitions and trends. For example, some scenarios may assume a gradual reduction in population growth, while others might anticipate higher population growth rates in specific regions. Trends in GDP per Capita (A): These pathways account for variations in economic development and affluence. Different SSPs may assume scenarios where global economic growth is more equitable or where certain regions experience rapid economic development. Trends in Carbon Intensity (T): The carbon intensity of energy and technology use is a crucial factor. SSPs take into account different assumptions about how efficiently society will use energy, whether there will be a transition to clean energy sources, and how technology will evolve. Assumptions within SSPs: Internally Consistent Trends: Each SSP is constructed with internally consistent trends in P, A, and T. For example, scenarios with rapid economic growth may be associated with lower population growth due to demographic transitions. These trends are based on plausible assumptions but do not predict specific future outcomes. Plausible Scenarios: SSPs encompass a range of plausible future scenarios, and no single scenario is considered definitive. They acknowledge the uncertainty associated with how population, affluence, and technology will evolve over time. Climate and Emission Projections: Climate models are used to estimate how each SSP's specific combination of P, A, and T will influence emissions and global temperatures. These models help determine the potential impact on the climate under each scenario. Long-Term Perspective: SSPs consider the long-term implications of various socioeconomic and technological trajectories. They highlight the importance of early actions in shaping the future climate, emphasizing that de

What kinds of climatic changes have we observed over the Earth's history? How does this compare with the record of the last ~11,000 years? (other card) Answer to this in THIS card : Why are the relatively small recent changes nonetheless cause for concern?

Speed of Change: One of the most significant concerns is the unprecedented speed of contemporary climate change. Natural climate shifts in the past occurred over thousands of years, allowing ecosystems and societies time to adapt. Current changes are occurring over decades, which may not provide sufficient time for adaptation. Ecosystem Impacts: Rapid climate change can lead to disruptions in ecosystems, loss of biodiversity, and the inability of many species to adapt or migrate quickly enough. This can have cascading effects on ecosystems and the services they provide. Sea Level Rise: Melting polar ice and thermal expansion of seawater are leading to rising sea levels. Even a relatively small increase in global temperatures can result in substantial sea-level rise, threatening coastal communities and infrastructure. Extreme Weather Events: The changing climate is associated with an increase in the frequency and intensity of extreme weather events, including hurricanes, heatwaves, droughts, and heavy rainfall events. These events can have devastating consequences for societies and economies. In summary, the key concern with contemporary climate change is not just that temperatures are increasing, but the speed at which they are doing so and the implications for human societies, ecosystems, and the planet's stability. Human activities are driving this rapid change, and addressing it is critical to avoid the most severe and irreversible impacts on the environment and society.

What are the basic steps in the scientific process?

Step 1: scientists generate and test hypotheses (following generally acceptedprocedures and rules of evidence) Step 2: these studies/tests undergo peer review (quality control 1) Step 3: peer-reviewed conclusions are (not) replicated (quality control 2) - Many results don't make it through this "crucible of science" (e.g., 2023 room-temp superconducter) - Numerous independent teams are unlikely to make the same mistakes; faulty results typically notreplicated Step 4: scientists test additional implications of theoretical claims ** Note: scientists are humans with interests and biases, but this can also serve science ----> If you could publish a paper credibly debunking anthropogenic climate change, you (and the publishing journal) would instantly become famous

What is the social cost of carbon (SCC)? Why do we need to know it? What information do we need to calculate it?

The Social Cost of Carbon (SCC) is a measure used to estimate the economic cost associated with the damages caused by the emission of one tonne of carbon dioxide (CO2) or its equivalent in other greenhouse gases. It represents the present value of the expected future damages, in monetary terms, resulting from the emission of an additional tonne of CO2. We need to know it because : Cost-Benefit Analysis: In the United States, for example, federal regulations must pass a cost-benefit test. This means that the benefits of a regulation (in terms of climate damages avoided) should outweigh the costs imposed on the economy. Knowing the SCC helps in quantifying the benefits side of this analysis. Policy Development: The SCC is used to inform and develop policies related to climate change mitigation and adaptation. For example, it can help in setting carbon prices, designing emissions reduction targets, and evaluating the economic impact of various climate policies. What info : Estimates of Current and Future Damages: This involves assessing the economic impacts of climate change, such as damage to infrastructure, health costs, agricultural losses, and changes in ecosystem services. These damages are quantified in monetary terms over time, considering different emission scenarios and climate projections. Discount Rate: The appropriate discount rate is used to convert future damages into their present value. This rate reflects how society values costs and benefits occurring in the future compared to the present. A lower discount rate places more weight on future damages, while a higher discount rate places more weight on present costs. The choice of discount rate has significant implications for the calculated SCC.

Different wavelengths of electromagnetic radiation have different properties. Why is this important for understanding the climate and climate change? (Hint: how does Earth's atmosphere "treat" different types of radiation differently?)

The properties of different wavelengths of electromagnetic radiation play a crucial role in understanding climate change because the Earth's atmosphere interacts differently with various types of radiation. This interaction has significant implications for how energy from the Sun is absorbed by the Earth and how heat is retained within the atmosphere. 1. **Solar Radiation (Visible Light)**: - Visible light from the Sun consists of photons with relatively short wavelengths. Earth's atmosphere is largely transparent to visible light, allowing it to pass through and reach the Earth's surface. - When solar radiation (visible light) reaches the Earth's surface, it is absorbed, warming the planet. This absorbed energy is re-radiated as longer-wavelength infrared radiation, contributing to the planet's heat content. 2. **Infrared Radiation (Heat)**: - Infrared radiation is associated with longer wavelengths and is the form of energy emitted by the Earth as it cools down. This radiation carries heat away from the Earth's surface. - Earth's atmosphere contains gases, such as carbon dioxide (CO2) and water vapor, which are relatively opaque to infrared radiation. This means that some of the infrared radiation emitted by the Earth is absorbed by these greenhouse gases, trapping heat in the atmosphere. - our atmosphere prevents infrared from escaping 3. **Greenhouse Effect**: - The differential behavior of Earth's atmosphere toward visible and infrared radiation is fundamental to the greenhouse effect. Visible solar radiation easily penetrates the atmosphere and warms the Earth, but the re-radiated infrared heat is partially trapped by greenhouse gases. - This natural greenhouse effect keeps the Earth's surface warmer than it would be in the absence of an atmosphere, making the planet habitable. 4. **Enhanced Greenhouse Effect and Climate Change**: The concern with climate change arises from the enhancement of the natural greenhouse effect. The increased concentration of greenhouse gases, primarily due to human activities like burning fossil fuels, intensifies the trapping of infrared radiation. This enhanced greenhouse effect leads to global warming, as more heat is retained in the atmosphere. It is responsible

Quiz 3 : Which of the following is NOT an example of climate mitigation? a) Moving from a flood zone to a safer place b) Installing rooftop solar panels to reduce your carbon emissions c) Taking public transportation to burn less gas d) Eating less meat to reduce methane emissions

a) Moving from a flood zone to a safer place

Human activity has, on balance, caused a radiative forcing (RF) of about +2.5 W/m2. This net change reflects a) positive RF from GHGs and negative RF from sulfate aerosols b) negative RF from GHGs and positive RF from sulfate aerosols c) positive RF from both GHGs and sulfate aerosols d) negative RF from both GHGs and sulfate aerosols

a) positive RF from GHGs and negative RF from sulfate aerosols GHGs have reduced Eout; aerosols have reduced Ein to a smaller degree SLide 25 of lecture 3

What does Dessler mean when he says that the impacts of climate change are non-linear? Can you give an example of non-linear effects?

When Andrew Dessler refers to the impacts of climate change as "non-linear," he means that the effects of climate change do not progress in a simple, linear fashion, where a small change in one variable leads to a proportionate change in the impact. Instead, these impacts can remain relatively minor for a period, and then suddenly escalate or become much more severe as certain thresholds or tipping points are crossed. In essence, non-linear impacts imply that the relationship between the extent of change in climate variables and the impact on ecosystems and human societies is complex and can exhibit abrupt changes. Here's an example to illustrate non-linear effects: Increased Rainfall and Flooding: Imagine a region where increased rainfall is occurring due to climate change. In the early stages, this additional rainfall may not pose significant problems. Rivers and drainage systems can handle the extra water, and communities can adapt to a slightly wetter environment. However, as the amount of rainfall continues to increase, there may come a point where the capacity of rivers and drainage systems is exceeded. This threshold could lead to sudden and severe flooding, causing damage to homes, infrastructure, and farmlands. The impact on the community becomes disproportionately greater compared to the incremental increase in rainfall. This example demonstrates non-linear impacts, where the consequences of climate change intensify rapidly once a certain level is reached. Such non-linear effects can be challenging to predict and manage, and they underscore the importance of taking early action to mitigate climate change and adapt to its potential consequences. Additionally, Dessler's point about climate change affecting different socioeconomic groups unevenly highlights that these non-linear impacts may disproportionately harm vulnerable populations, such as the poor, who often lack the resources and resilience to cope with sudden and severe changes in climate. The poor are less shielded - they often experience the burdens of climate change before the wealthy!

Dessler discusses the idea that plate tectonics, solar activity, or changes to the Earth's orbit may have caused recent climate change. In general, his response is that a) these kinds of changes never affect the climate b) these kinds of changes are important but occur too slowly to have caused recent climate change c) these kinds of changes have definitely contributed to recent climate change d) we don't know if these kinds of changes have contributed to recent climate change

b) these kinds of changes are important but occur too slowly to have caused recent climate change

Quiz 2 : Venus is much hotter than Mercury: 735 K versus 452 K. How can we explain this? a) Venus receives more solar energy than Mercury b) Mercury has a higher albedo than Venus c) Venus has a greenhouse gas (GHG)-rich atmosphere while Mercury does not d) All of the above e) None of the above

c) Venus has a greenhouse gas (GHG)-rich atmosphere while Mercury does not

The main reason contemporary climate change is a concern is that a) the Earth has never experienced such high temperatures before b) humans and other species are adapted to our current climate c) we don't know why it's happening d) there's nothing we can do about it

b) humans and other species are adapted to our current climate. Climate change, particularly the rapid and anthropogenic (human-induced) climate change observed in recent decades, disrupts ecosystems and weather patterns. These changes can have severe consequences for the adaptability and survival of both human societies and other species. Therefore, the fact that humans and various species are adapted to the current climate makes climate change a significant concern. - Physiological Adaptation: Organisms have evolved specific physiological mechanisms to thrive in their current climate. For humans, this includes our ability to regulate body temperature, adapt to varying seasons, and live in different climates around the world. - Behavioral Adaptation: Humans and species have developed behaviors suited to their current climate. For example, agricultural practices, hunting and gathering methods, and migration patterns are often based on seasonal and climatic conditions. - Ecological Adaptation: Species in ecosystems are interconnected and have co-evolved within specific climate zones. Changes in climate can disrupt these ecological relationships, leading to imbalances and potentially causing extinctions. - Infrastructure and Settlements: Human societies have built infrastructure, homes, and cities tailored to current climate conditions. Climate change can impact these structures and disrupt the functionality of cities. - Economic and Agricultural Practices: Agriculture is highly dependent on climate. Changes in temperature, precipitation, and growing seasons can affect crop yields and food production. Economic activities, like fishing and forestry, are also climate-dependent.

Quiz 2 : Greenhouse gases like carbon dioxide and methane constitute a) about 40 percent of Earth's atmosphere b) about 10 percent of Earth's atmosphere c) about 5 percent of Earth's atmosphere d ) less than 1 percent of Earth's atmosphere

d ) less than 1 percent of Earth's atmosphere

Quiz 2: Adding an atmospheric layer to a planet a) traps energy the surface would otherwise radiate into space b) reflects energy back to the surface c) requires the surface to warm to maintain energy balance d) All of the above e) None of the above

d) All of the above

Quiz 3 : To calculate the social cost of carbon (SCC), we need to know a) how climate change will affect us in 20 years b) how climate change will affect us in 100 years c) how much we care about the future relative to the present d) All of the above

d) All of the above

Quiz 3 : Which of the following do global climate models (GCMs) NOT do? a) Divide the Earth into many small grid squares b) Model all known physical processes within each grid square c) Generate predictions about the likely consequences of further GHG emissions d) Generate predictions about humanity's future emissions path

d) Generate predictions about humanity's future emissions path

Quiz 3 : Which of the following is NOT incorporated into shared socioeconomic pathways (SSPs)? a) Predictions about future population growth b) Predictions about future economic growth c) Predictions about future technological progress d) Predictions about the impact of future GHG emissions

d) Predictions about the impact of future GHG emissions

Quiz 1 : Which of the following types of evidence point to a warming climate? a) Surface and satellite-based temperature anomalies b)Ocean temperature anomalies c) Glacial and sea ice d) Sea levels e) All of the above

e) All of the above

What does Dessler mean when he talks about "cherry picking" evidence? How does this relate to the "warming pause" of the early 2000s?

"cherry picking" evidence refers to the selective use of data or information to support a particular viewpoint while ignoring or omitting data that contradicts that viewpoint. It's a practice where individuals or groups choose specific pieces of evidence that align with their preconceived beliefs or arguments, effectively presenting a biased or one-sided view of the topic. - Cherry-picking can be misleading and deceptive because it creates a skewed or incomplete picture of the scientific consensus or understanding. It often involves emphasizing isolated data points or studies that seem to support a particular position while disregarding the broader body of evidence or research that may provide a more balanced or accurate perspective. The mention of the "warming pause" in the early 2010s, as reported by Fox News, is an example of cherry-picking data. By highlighting a specific period in which the rate of global warming appeared to slow down or pause, the report creates the impression that global warming isn't a consistent or long-term trend. The term "Going down the up escalator" suggests that while the long-term trend is upward (indicating global warming), one can focus on shorter periods where temperatures may appear to decline or remain steady, giving the illusion of a "cooling" trend. This is a classic example of cherry-picking data to misrepresent the overall trend. In the case of climate change, it's used to downplay or deny the overall trend of global warming by emphasizing short-term fluctuations or periods of less rapid warming. Scientists and experts emphasize the importance of looking at long-term trends and considering the full body of evidence when assessing complex issues like climate change to avoid the pitfalls of cherry-picking. The idea of the "warming pause" focused on a relatively short time period, often starting around the late 1990s or early 2000s. Climate change is a long-term phenomenon, and examining a short timeframe in isolation can give a misleading impression. Natural Variability: Climate systems exhibit natural variability, and short-term fluctuations in temperature are not uncommon. A brief slowdown in the rate of warming doesn't negate the overall trend of global warming,

Why is it useful to be able to predict both climate and weather?

- Climate predictions are crucial for understanding long-term trends and changes in the Earth's climate. These predictions help us assess the impacts of human activities, such as greenhouse gas emissions, on the planet's climate system. - They provide the foundation for addressing global issues like climate change, as they inform policymaking and mitigation strategies. - Weather, in contrast, pertains to short-term atmospheric conditions, typically from minutes to a few weeks. It focuses on specific, local events like daily temperature, rain, or storms. - Weather predictions are essential for public safety, agriculture, transportation, and disaster preparedness. They help us make short-term decisions and plan daily activities. -These forecasts rely on understanding the current state of the atmosphere through observations and models that project its behavior over short timeframes. In summary, both climate and weather predictions are vital for distinct reasons. Climate predictions are essential for addressing long-term global issues like climate change and sustainability, while weather predictions are crucial for everyday decision-making and emergency response. The scientific community, therefore, recognizes the importance of forecasting both climate and weather to serve the diverse needs of society and address the challenges associated with climate variability and change.

What does the scientific consensus tell us about climate change? (I'm asking here about whether and how the climate is changing—don't worry about the "why" for now.) - On what evidence is this consensus based?

- When numerous studies obtain the same results, a scientific consensus emerges (Of 88,125 peer-reviewed studies, 99.9 percent agree that the climate is changing and that human activity is the cause) -The climate is changing: temperature anomalies make this clear - Absolute temperatures vary tremendously across short distances (due to vegetation, urbanization, and microclimates), so we'd need a LOT of thermometers to measure a regional/national global average -- Climate scientists rely on temperature anomalies: the difference between the absolute temperature and some reference temperature (e.g., the 1990-2010 average) -- These anomalies are strongly correlated across space, so we don't need many thermometers to measure regional/national/global averages (about 100 for the whole world IPCC Reports: The Intergovernmental Panel on Climate Change (IPCC), comprised of thousands of climate scientists from around the world, regularly assesses and summarizes the scientific consensus on climate change. Their comprehensive reports provide a synthesis of the evidence and expert judgment. Global Temperature Rise: One of the most significant pieces of evidence is the global increase in average temperatures. Surface temperature records, satellite data, and temperature measurements from the ocean all show a consistent pattern of warming over the past century. Ocean Acidification: The absorption of excess carbon dioxide (CO2) by the oceans has led to ocean acidification, which can have harmful effects on marine ecosystems. This is a consequence of increased atmospheric CO2 levels. Rising Sea Levels: Sea levels are rising due to the melting of glaciers and the thermal expansion of seawater as it warms. This is observed globally and is consistent with the increased heat content of the oceans. Melting Ice: The widespread retreat of glaciers, the shrinking of ice sheets in Antarctica and Greenland, and the reduced extent of Arctic sea ice are all clear indicators of a warming climate.

What are some alternatives to accepting the scientific consensus? Why are these alternatives flawed?

1) Conspiracy Theories: Some individuals reject the scientific consensus and instead embrace conspiracy theories. This can involve believing that scientists are part of a global conspiracy to deceive the public. This approach is flawed because it lacks credible evidence, relies on mistrust, and often involves highly implausible scenarios that would require the cooperation of numerous individuals. Cherry-Picking Data: Instead of accepting the entire body of evidence that forms a consensus, some people selectively choose data or studies that support their pre-existing beliefs while ignoring conflicting information. This is flawed because it distorts the overall picture and can lead to confirmation bias, reinforcing existing opinions rather than seeking objective truth. Appeal to Personal Experience: Some individuals may rely solely on their own personal experiences or anecdotal evidence to challenge the consensus. This approach is flawed because individual experiences can be highly subjective and may not be representative of broader trends or scientific realities. Appeal to Authority: Another alternative is to reject the consensus by appealing to the authority of a single dissenting expert or a small group of dissenting experts. This is flawed because it disregards the weight of evidence and consensus within the broader scientific community, which often reflects a more accurate picture of our understanding.

ACTUAL QUESTION: "Discuss four types of evidence that tell us the Earth's climate is changing." This is a 4-point question, and my answer consisted of four short sentences, each of which described a type of evidence.

1) Glaciers, which are massive bodies of ice, are highly sensitive to temperature changes. Over the past century, the majority of glaciers on Earth have been shrinking at an alarming rate. 2) Ecosystem changes, reflected in altered species distribution and behavior, with earlier flower blooming, bird migrations, and habitat shifts indicating a shifting climate. These changes demonstrate that climate impacts extend beyond temperature, affecting entire ecosystems and potentially leading to species extinctions, a result of rapid global warming, rather than natural fluctuations. 3) Ice cores, sediment samples, and other geological records offer a window into the past. They reveal that the current warming trend is unprecedented in recent history. While the Earth's climate has naturally fluctuated over geological time scales, the rate and magnitude of the current warming are exceptional. 4) Ocean acidification, caused by the absorption of excess carbon dioxide from human activities into the oceans. The resulting decrease in ocean pH is a direct consequence of rising atmospheric CO2 levels and highlights the human-induced alterations in the planet's carbon cycle, confirming the reality that Earth's climate is changing.

Be prepared to discuss the seven broad categories of climate impacts covered in lecture. Specifically, you should be able to state some central concerns within each category and explain how climate change contributes to these concerns Expanded on the first 2 : 1) Temperature 2) Sea level rise and acidification

1) Temperature - Average temperatures have risen and will continue to rise - high and low temperatures will continue to rise overall - the change in highs and lows can be very disruptive - High temperatures can lead to deadly heatwaves, particularly in urban areas. Extremely hot days can result in heat-related illnesses and even fatalities Temperature extremes can have a significant impact on agriculture. High temperatures can damage or kill crops, reduce yields, and disrupt the timing of planting and harvesting. Conversely, low temperatures, especially unexpected frosts, can harm crops and reduce agricultural productivity (Variability in temperature can affect food production. Inconsistent weather patterns can lead to reduced crop yields and affect the stability of the global food supply chain) Changes in highs and lows can disrupt natural habitats, alter breeding and migration patterns of wildlife 2) Sea level rise and acidification Sea levels will continue to rise due to melting of continental ice sheets Sea level rise threatens millions of people who live in coastal regions. Many of the world's major cities and critical infrastructure are located near the coast. Even a modest increase in sea levels can lead to coastal flooding, erosion, and saltwater intrusion into freshwater sources. The vulnerability of coastal areas to sea level rise makes it a pressing concern for both human populations and the economies that depend on these regions. - As the oceans absorb more co2, they will become more acidic --The increased acidity makes it harder for these organisms to build and maintain their calcium carbonate structures. As a result, they become more vulnerable to damage. This is a threat to biodiversity in the oceans --> disrupts the entire food web, potentially leading to reduced fish stocks and impacting global seafood supplies. Marine ecosystems provide a wide range of valuable ecosystem services, including protection against storm surges, water filtration, and carbon storage. The degradation of these ecosystems due to acidification can result in the loss of these services, affecting both human well-being and the environment.

What assumptions does Dessler make about the atmosphere in his one-layer climate model?

1. Earth's atmosphere is transparent to visible photons, which pass through and are absorbed by surface 2. Atmosphere is opaque to infrared photons, all of which are absorbed by atmosphere 3. Atmosphere behaves like a blackbody, emits photons based on internal energy equally in both directions (upward and downward) 4. Photons emitted upward go into space (Eout); photons emitted downward are absorbed by surface Rephrased with more explanation : 1. Transparency to Visible Photons: The model assumes that Earth's atmosphere is transparent to visible photons. This means that sunlight in the form of visible light is assumed to pass through the atmosphere without significant absorption or interaction and is absorbed by the Earth's surface. 2. Opacity to Infrared Photons: Dessler's model assumes that the atmosphere is opaque to infrared photons. Infrared radiation, which is emitted by the Earth as it cools down, is assumed to be entirely absorbed by the atmosphere. This is in line with the greenhouse effect concept, where certain gases in the atmosphere, such as carbon dioxide and water vapor, absorb and re-emit infrared radiation. 3. Atmosphere as a Blackbody: The atmosphere is treated as a blackbody in the model. A blackbody is an idealized construct that emits radiation based on its internal energy and temperature, and it emits radiation equally in both upward and downward directions. This assumption simplifies the treatment of energy transfer within the atmosphere. 4. Radiative Exchange: Photons emitted upward from the atmosphere are assumed to escape into space, contributing to the energy output (Eout). Photons emitted downward by the atmosphere are assumed to be absorbed by the Earth's surface, increasing the Earth's internal energy (Ein).

1. If an object's Ein = Eout, what does this imply about the object's temperature? 2. What if Ein > Eout? 3. What if Ein < Eout?

1. If an object's Ein = Eout - his implies that the object is in a state of thermal equilibrium. In other words, the rate at which energy is being absorbed by the object (Ein) is equal to the rate at which it is emitting energy (Eout). The object's temperature remains constant, and there is no net change in its internal energy. - the temperature of the object is not changing + the internal energy of the object is not changing 2. If Ein>Eout: This suggests that the object is gaining more energy from its surroundings than it is radiating back. As a result, the object's internal energy will increase, and its temperature will rise. It is undergoing a process of heating. 3. If Ein<Eout: In this case, the object is losing more energy to its surroundings than it is absorbing. As a consequence, the object's internal energy decreases, and its temperature decreases. It is undergoing a process of cooling.

What is the Earth's Ein in W/m2? What two factors determine this value

238 w/m^2 1. The Solar constant -- This represents the amount of solar energy received at the outer atmosphere of the Earth. On average, the solar constant is about 1360 watts per square meter (W/m²). 2. the angle at which sunlight strikes the Earth's surface. This angle depends on the latitude and time of day. When the Sun's rays are more perpendicular to the surface (e.g., at the equator at solar noon), the energy input is more concentrated, resulting in higher values of Ein. Conversely, at higher latitudes and when the Sun is lower in the sky, the angle of incidence is shallower, and the energy input is more spread out, leading to lower values of Ein. Slide 8/9 of lecture 2

3) Precipitation and extreme weather the overall increase in global temperatures leads to more evaporation and increased global precipitation, it's the distribution of this precipitation that's concerning. The "wet gets wetter, dry gets drier" phenomenon means that regions already prone to drought may experience even less rainfall, exacerbating water scarcity and agricultural challenges -- what goes up must come down which means more precipitation. This precipitation will be unevenly distributed across space and time. Space : "wet gets wetter, dry, gets drier" - climate change will exacerbate existing climate conditons Time : less frequent but heavier downpours, a heavier downpour means more flooding (and drought), more intense hurricanes Increased flooding can destroy habitats and disrupt ecosystems. Meanwhile, prolonged droughts can threaten the survival of plant and animal species, potentially leading to population declines and extinctions. Shift in Precipitation Form: More regions are experiencing rain instead of snow, which affects snowpacks. Snowpacks act as natural reservoirs, gradually releasing water during the warmer months. The loss of snowpacks can result in water shortages during the dry season.

4) Droughts and wildfires -- greater evaporation = less frequent precipitation = more droughts = bad for crops Hotter and drier conditions, fuel wildfires Droughts significantly impact agriculture by reducing water availability for irrigation. Prolonged droughts can lead to crop failures, lower yields, and decreased food production. This affects food security, as it can result in food shortages, increased food prices, and potential famine. Moreover, water scarcity due to droughts affects drinking water supplies Droughts and wildfires disrupt natural ecosystems. They can lead to habitat destruction, loss of biodiversity, and long-term ecological consequences. The destruction of ecosystems can have a cascading effect on other species, including those that depend on them for survival. Loss of Lives and Homes: Both droughts and wildfires pose a direct threat to human lives and property. Wildfires, in particular, can spread rapidly, leaving little time for evacuation. Health and Well-being: Droughts can contribute to water shortages, affecting sanitation and hygiene. Reduced water availability can lead to waterborne diseases, malnutrition, and health issues. Wildfires generate air pollution through the release of fine particulate matter and toxic gases, which can cause respiratory problems and other health issues in affected communities.

5) Species extinction and ecosystem collapse -currently living through the Holocene extinction. Many species will have a hard time adapting -Aside from their intrinsic value, threatened ecosystems provide "ecosystem services" - Coral reefs provide protection from storm surges, $$ from food and tourism - Bees pollinate many crops - Loss of species/ecosystems threatens humans as well - Biodiversity is essential for ecosystem stability and resilience. Diverse ecosystems tend to be more adaptable to environmental changes, including climate change. When species disappear, it can disrupt the intricate web of interactions within ecosystems. - ecosystem Services: Ecosystems provide essential services that are critical for human survival and well-being. These services include pollination (by bees and other insects), water purification, carbon sequestration, and protection against natural disasters (e.g., mangroves and coral reefs mitigating storm surges). Ecosystem collapse can disrupt these services, affecting agriculture, water quality, and disaster risk reduction. -Economic Impact: Biodiversity loss can lead to economic losses. For instance, the decline of pollinators can reduce crop yields, affecting agricultural economies. Additionally, the collapse of fisheries can devastate coastal communities that rely on seafood for livelihoods.

6) Refugee crises Magnitude of Displacement: Climate change-induced displacement affects millions of people. Rising sea levels, extreme weather events, and food and water scarcity can force individuals and entire communities to leave their homes. The sheer scale of this displacement is a humanitarian challenge of unprecedented proportions. International Response: The international community is often ill-prepared to handle such massive migration flows. Host countries may struggle to provide shelter, healthcare, and basic services to an influx of refugees. This can strain already limited resources, potentially leading to political tensions between host communities and refugees. Geopolitical Tensions: Host nations may view refugee influxes as a threat to their stability and resources. Disputes can arise over borders, resources, and migration policies. Geopolitical conflicts can escalate in regions already prone to instability. National Security Concerns: Mass migration can strain border controls, potentially providing opportunities for criminal activity and terrorism. Governments may need to redirect resources from other national security priorities to manage refugee crises. Human Rights: Climate refugees may face discrimination, exploitation, and violence, both during their journeys and in host countries. These human rights abuses further exacerbate the crisis and pose a moral and ethical challenge for the international community. Economic Impact: Climate-induced displacement can disrupt local economies, reducing agricultural productivity and causing loss of infrastructure. This economic instability can have a cascading impact on the affected region and, in some cases, lead to further displacement as people search for better opportunities elsewhere. Global Responsibility: Climate change is a global issue, and the responsibility for addressing its consequences is shared. The countries emitting the most greenhouse gases bear a moral obligation to assist regions disproportionately affected by climate impacts. The challenge lies in forging international agreements and mechanisms for sharing the burden. Long-Term Implications: Climate-induced displacement often results in prolonged displacement, with refugees un

Which components of Earth's atmosphere are GHGs? Approximately how much of the atmosphere do they constitute?

78% of dry atmosphere is diatomic nitrogen (N2); 21% is diatomic oxygen (O2); around 1% is argon = These components (>99%) do NOT absorb infrared photons; are not GHGs Remaining GHGS : Water Vapor (H2O): Water vapor is a naturally occurring greenhouse gas, and its concentration in the atmosphere varies with temperature and humidity. While it is the most abundant GHG, its concentration is highly variable and controlled by natural processes. --> Warming increases evaporation, creating a positive climate feedback CO2 : current concentration in the atmosphere is approximately 0.0412%, which is equivalent to 412 parts per million (ppm). CO2 is released into the atmosphere through various human activities, such as burning fossil fuels and deforestation, and it has a significant impact on global warming. c02 absorbs infrared photons - it is the most important GHG that humans directly control Methane (CH4): current concentration is about 1.87 ppm. Although it exists in much smaller quantities than CO2, it is approximately 32 times more effective at trapping heat in the atmosphere. Other gases also matter—nitrous oxide, ozone, halocarbons (chloro and hydrochloroflourocarbons)—but we'll mostly focus on CO2 and CH4

Why is a planet's albedo (α) important for its climate?

A planet's reflectivity is its albedo (α), the fraction of photons reflected back into space Albedo represents the fraction of incoming solar radiation (sunlight) that is reflected by the planet's surface. Here's why albedo is important for a planet's climate and its relevance to climate change: 1. **Influence on Planetary Temperature**: - Albedo affects the planet's temperature. Planets with high albedo reflect a significant portion of incoming solar radiation back into space, resulting in cooler surface temperatures. Low-albedo planets, on the other hand, absorb more solar radiation, leading to higher surface temperatures. 2. **Feedback Mechanism**: - Albedo can be a part of feedback mechanisms in the climate system. For example, when ice and snow on Earth's surface melt due to rising temperatures, it reduces the planet's overall albedo. As a result, more solar radiation is absorbed, leading to further warming and more ice melt—a positive feedback loop that can exacerbate climate change. 3. **Climate Change Implications**: - Changes in a planet's albedo can have significant implications for climate change. In the case of Earth, human activities such as deforestation, urbanization, and the release of greenhouse gases lead to changes in land cover and surface properties, which, in turn, affect albedo. For example, the expansion of dark, heat-absorbing surfaces like asphalt and reduced forest cover can decrease albedo, contributing to local and global warming. 4. **Polar Amplification**: - In polar regions, the albedo effect is especially important. When ice and snow melt in polar areas, the darker surfaces underneath, such as the ocean or bare ground, absorb more solar radiation, leading to local warming and further ice melt. This polar amplification can have far-reaching consequences for global climate dynamics. 5. **Climate Models**: - Albedo is a key parameter in climate models. Accurate representation of albedo is crucial for predicting how changes in land use, land cover, and greenhouse gas concentrations will affect the Earth's climate. 6. **Planetary Comparisons**: albedo is a critical factor in understanding their climates. For example, the high albedo of Venus due to its thick cloud cover resu

What are some examples of abrupt climate change impacts?

Abrupt climate change impacts refer to sudden and significant shifts in the Earth's climate system that can have far-reaching and severe consequences. These impacts often occur when certain thresholds or "tipping points" are crossed. Here are some examples: Rapid Disintegration of Ice Sheets: The disintegration of major ice sheets, such as the West Antarctic or Greenland ice sheets, could lead to a rapid and substantial rise in sea levels. This could result in the inundation of coastal areas, displacing millions of people and causing widespread economic and environmental damage. Shutdown of Atlantic Meridional Overturning Circulation (AMOC): The AMOC is part of the ocean's circulation system and plays a crucial role in regulating regional climate patterns. If the AMOC were to slow down or shut down, it could disrupt weather patterns, leading to colder temperatures in some regions and potentially more frequent extreme weather events. Thawing of Permafrost: Permafrost contains vast amounts of organic carbon that has been preserved in a frozen state for thousands of years. When permafrost thaws, this carbon is released into the atmosphere as greenhouse gases, exacerbating global warming and further accelerating climate change. Rapid Dying of Amazon Rainforest: The Amazon rainforest is a vital carbon sink and a biodiversity hotspot. If deforestation and climate change disrupt the delicate balance of this ecosystem, it could lead to a rapid decline in its ability to sequester carbon and support diverse life forms, with cascading effects on the global climate and ecosystems. These abrupt climate change impacts are characterized by their potential for rapid and severe consequences. While the likelihood of these events occurring in the near future may be low, their potential impacts are so significant that they warrant serious consideration in climate risk assessment and policy planning. Preventing these abrupt changes is one of the key reasons for urgent action to mitigate climate change and reduce greenhouse gas emissions.

What, in general, are adaptation policies? Can you give some specific examples?

Adaptation policies refer to measures and strategies implemented to respond to the negative impacts of climate change. These policies aim to reduce the vulnerability of communities, ecosystems, and infrastructure to the changing climate and its associated risks Seawalls and Coastal Protection: Seawalls, dikes, and coastal protection infrastructure are designed to mitigate the impacts of sea-level rise and storm surges. These structures help prevent coastal erosion, protect valuable assets, and safeguard communities from inundation due to rising seas. Flood Management and Levees: Flood-resistant infrastructure, such as levees and flood barriers, is essential for areas prone to increased precipitation and flooding. These structures help control and redirect floodwaters to prevent damage to properties and safeguard lives. Irrigation and Water Management: In regions facing drought and changing precipitation patterns, irrigation systems and improved water management practices are critical for agriculture. These measures ensure a reliable water supply for crops and help maintain food security. Heat-Resistant Buildings and Cooling Solutions: As temperatures rise, heat-resistant building designs and the widespread use of air conditioning are essential for maintaining human comfort and health. Proper insulation, energy-efficient cooling systems, and urban planning can help reduce the urban heat island effect. Climate-Resilient Agriculture: Engineering climate-resilient crops and livestock is necessary to maintain food production under changing climate conditions. Breeding and genetic modification can create heat- and drought-tolerant plant varieties and disease-resistant animal breeds. Physical Relocation: In some cases, the impacts of climate change may necessitate the relocation of communities or infrastructure. This is especially relevant for areas threatened by sea-level rise or extreme weather events. Managed retreat strategies can help communities move to safer locations.

Quiz 2 : Which of the following would lead to positive radiative forcing? a) "Energy In" increases by 10 while "Energy Out" increases by 5 b) "Energy In" decreases by 5 while "Energy Out" decreases by 10 c) "Energy In" increases by 5 while "Energy Out" decreases by 5 d) All of the above e) None of the above

All of the above! 1. "Energy In" increases by 10 while "Energy Out" increases by 5: - Δ(Energy In) = +10 - Δ(Energy Out) = +5 Δ(Energy In) - Δ(Energy Out) = +10 - (+5) = +10 - 5 = +5 This scenario results in a net increase in energy retained by the planet, which leads to positive radiative forcing. 2. "Energy In" decreases by 5 while "Energy Out" decreases by 10: - Δ(Energy In) = -5 - Δ(Energy Out) = -10 Δ(Energy In) - Δ(Energy Out) = -5 - (-10) = -5 + 10 = +5 This scenario also results in a net increase in energy retained by the planet, which leads to positive radiative forcing. 3. "Energy In" increases by 5 while "Energy Out" decreases by 5: - Δ(Energy In) = +5 - Δ(Energy Out) = -5 Δ(Energy In) - Δ(Energy Out) = +5 - (-5) = +5 + 5 = +10 This scenario results in a larger net increase in energy retained by the planet, which leads to positive radiative forcing. Therefore, all of the given scenarios lead to positive radiative forcing.

ACTUAL QUESTION: Explain how and why changes in n, S and α affect a planet's temperature. This is a 3-point question, and my answer consisted of three sentences, each of which looked something like "An increase in X raises/lowers the planet's temperature because _____." You get 0.5 points for correctly identifying how each variable affects temperature (i.e., increase or decrease) and 0.5 points for explaining why (i.e., what's the mechanism?).

An increase in the number of atmospheric greenhouse gases (n) raises the temperature because these gases trap heat from the sun, creating a greenhouse effect that warms the planet. An increase in solar radiation (S) raises the temperature because it directly adds heat to the Earth's surface. An increase in planetary albedo (α) lowers the temperature because it reflects more sunlight back into space, reducing the energy absorbed by the planet and thereby cooling it. ANOTHER WAY OF SAYING IT : An increase in the number of greenhouse gases (N) raises the temperature because it enhances the greenhouse effect, trapping more heat within the atmosphere (eout) and consequently increasing Ein. An increase in the solar constant (S) raises the planet's temperature because it results in higher incoming solar radiation (Ein), which directly warms the planet. A decrease in planetary albedo (α) raises the temperature because it reduces the amount of solar energy reflected back to space, leading to higher Ein.

How does carbon move between these various components? - Atmosphere, Land Biopshere, Ocean, Rock Resevoir

Atmosphere-Ocean Exchange: CO2 dissolves in seawater, leading to the formation of carbonic acid. The reverse reaction releases CO2 back into the atmosphere. This process cycles approximately 60 GtC (gigatonnes of carbon) between the atmosphere and the ocean each year, helping regulate atmospheric CO2 levels. However, it also leads to ocean acidification, which has ecological consequences. Atmosphere - land - biosphere : The land biosphere, including forests, vegetation, and soil, stores a substantial amount of carbon. This carbon is cycled through processes like photosynthesis and respiration. During photosynthesis, plants absorb CO2 from the atmosphere and use it to create carbohydrates while releasing oxygen. During respiration, animals and microorganisms consume carbohydrates and convert them into energy, releasing CO2 back into the atmosphere. Atmosphere-Rock Exchange: Most of Earth's carbon is stored in rocks, like limestone. This exchange is slow but significant in the long term. Volcanic eruptions release carbon into the atmosphere, while chemical weathering removes CO2 from the atmosphere as it reacts with rainwater and rocks. The turnover of carbon between the atmosphere-land biosphere-ocean system and the rock reservoir is a very slow process, occurring over hundreds of thousands of years. Human Perturbations to the Carbon Cycle: Humans have significantly altered the carbon cycle by burning fossil fuels (coal, oil, natural gas) for energy. This process transfers carbon from the rock reservoir into the atmosphere at a much faster rate than natural processes. The release of carbon into the atmosphere from fossil fuel combustion has led to increased atmospheric CO2 concentrations, contributing to global warming and climate change. In summary, the carbon cycle involves the continuous movement of carbon among the atmosphere, land biosphere, ocean, and rock reservoir, with human activities playing a significant role in perturbing this cycle.

What is attribution science? How does it help us attribute specific weather events to broader climate change?

Attribution science, in the context of climate change, is a field of research that focuses on understanding the extent to which human activities have contributed to specific extreme weather or climate events. It helps us attribute these events to broader climate change by using increasingly sophisticated models to estimate the likelihood of such events occurring both with and without the influence of anthropogenic climate change. Quantifying Likelihood: Attribution scientists use advanced climate models and observational data to simulate the occurrence of extreme weather events. They run simulations for both the current climate, which includes human-induced climate change, and a hypothetical "world without climate change." By comparing the likelihood of the event in these two scenarios, they can quantify how much climate change has influenced the event's occurrence. Statistical Significance: If the likelihood of an extreme event occurring in a world without climate change is very low, it suggests that climate change has played a significant role. For example, if a specific heatwave event would only occur once in 30,000 years in the absence of climate change but has become more frequent in the current climate, it strengthens the case for climate change attribution. Probabilistic Statements: Attribution science offers probabilistic statements. For instance, scientists might say that climate change has doubled the chances of a particular event occurring. This nuanced approach helps to communicate the level of influence human activities have had. Disaster Preparedness: Understanding the role of climate change in extreme events can inform disaster preparedness and response strategies. It allows communities and governments to better anticipate and plan for events that are now more likely to occur. Risk Assessment: Businesses, insurers, and government agencies use attribution science to assess climate-related risks. They can adjust their strategies, investments, and policies based on the likelihood of extreme events linked to climate change. In summary, attribution science provides a powerful tool for unraveling the complex relationship between climate change and extreme weather events. By quantifying the influ

What is climate? How does it differ from weather?

Climate is overall weather in an area over a long period of time. It is different from weather because weather is short term while climate is long term. Climate: The slowly varying aspects of the atmosphere-hydrosphere-land surfacesystem...typically characterized in terms of suitable averages of the climate system over periods of a month or more Weather: The state of the atmosphere...As distinguished from climate, weather consists of the short-term (minutes to days) variations in the atmosphere Climate and weather involve similar outcomes (temperature, precipitation, humidity, cloudiness, wind, etc.), but climate is a long-term average Averaging is crucial to distinguish the long-term climate signal from short-term weather noise

Why should we have more faith in "consensus" beliefs?

Cumulative Knowledge: Scientific consensus represents the collective understanding of experts in a particular field. Over time, scientific knowledge accumulates as more research is conducted. When a consensus forms, it signifies that a substantial body of evidence has consistently supported a particular explanation or theory. Peer Review: Scientific research goes through a rigorous peer-review process before publication. This involves independent experts in the field critically evaluating the research methodology, data, and conclusions. Consensus often emerges after research has withstood this scrutiny. Reproducibility: Consensus is built on findings that can be independently reproduced by other researchers. This reproducibility is a fundamental tenet of scientific inquiry and adds to the reliability of consensus beliefs. Reduction of Bias: The scientific process aims to minimize individual and systemic biases. Through peer review, replication, and the use of statistical methods, science strives to be objective and impartial in forming consensus beliefs. Continual Challenge: The scientific community encourages continuous questioning and reevaluation of existing beliefs. Consensus is not static; it can evolve or change in response to new evidence or more refined theories. Public Scrutiny: Scientific findings are open to public scrutiny and debate, which helps ensure transparency and accountability. This openness promotes a higher degree of confidence in consensus beliefs.

Mitigation : What kinds of broad changes do these policies need to bring about?

Energy Transition: Shifting from fossil fuels to clean and renewable energy sources for electricity generation. This involves deploying solar, wind, hydro, and nuclear power, along with advancing energy storage technologies. Electrification: Transitioning energy usage to electricity, which can be generated more cleanly. This includes electrifying transportation (electric vehicles), heating (heat pumps), and industrial processes. ** Note prong 1 and 2 must work together - electricity must be garnered cleanly Reduce/replace use of things that can't be electrified : Efficiency Improvements: Implementing energy-efficient technologies and practices in buildings, industrial processes, and transportation. This reduces the amount of energy required for a given task, thereby lowering emissions. Behavioral Changes: Encouraging changes in consumption patterns and behaviors that reduce emissions. This may include promoting public transportation, reducing meat consumption, and encouraging the use of energy-efficient appliances. Innovation: Investing in research and development to create new technologies and solutions that have lower carbon footprints. This can involve advancements in carbon capture and storage, sustainable agriculture, and clean energy.

Climate feedback : Can you give examples of fast and slow feedbacks? How do these feedbacks affect Earth's climate sensitivity?

Examples of fast feedbacks include: Water Vapor Feedback: As the atmosphere warms due to increased greenhouse gases, it can hold more water vapor. This additional water vapor acts as a greenhouse gas itself, further enhancing the warming effect. Examples of slow feedbacks include: Ice-Albedo Feedback: As polar ice and glaciers melt due to rising temperatures, they expose darker surfaces (such as open water or bare ground) that absorb more sunlight, leading to more warming and further ice melt. This feedback is associated with the reflectivity (albedo) of Earth's surface. As temperatures rise, polar ice caps and glaciers melt, reducing the planet's overall reflectivity. This decreased reflectivity results in more solar energy absorption, which leads to further warming. Ice-albedo feedback operates over longer timescales. Melting of Antarctic and Greenland Ice Sheets: The response of these massive ice sheets to warming is slow and can take centuries to millennia. As they melt, they contribute to sea-level rise. Thawing Permafrost: As permafrost in the Arctic thaws, it releases methane and carbon dioxide, which were previously trapped in the frozen ground. These greenhouse gases further contribute to global warming. Weathering Thermostat: This feedback operates on geological timescales. When CO2 levels rise, it can lead to increased chemical weathering of rocks, which gradually removes CO2 from the atmosphere, acting as a long-term climate regulator. sensitivity : Slow feedbacks contribute to higher climate sensitivity over longer periods, even if greenhouse gas emissions were to be reduced or stabilized. This is because they introduce delayed responses that can persist for centuries or more. (These feedbacks, such as the ice-albedo and carbon feedbacks, can continue to intensify warming over centuries, even if greenhouse gas emissions were to be reduced or stabilized.) - fast feedbacks amplify the initial temperature changes and contribute to a higher climate sensitivity, especially in the short term. Slow feedbacks, while operating over longer timescales, can substantially increase long-term climate sensitivity. Slow feedbacks contribute to higher climate sensitivity over longer periods, even if greenhouse

How long does CO2 remain in the atmosphere? (For concreteness, you can interpret this question as "How long does it take to remove 70 percent of a CO2 "pulse" from the atmosphere?") What are some important implications of these numbers?

Fast Exchange: Carbon moves relatively quickly between the atmosphere and the land biosphere (plants and ecosystems) and the upper layers of the ocean. These parts of the carbon cycle can remove a significant portion of a CO2 pulse from the atmosphere within shorter timescales, on the order of decades to centuries. Approximately 50% of a CO2 pulse is removed within about 50 years through these fast-exchange mechanisms. Slower Exchange: However, for deeper removal of CO2, the carbon needs to be transported into the deep ocean, where carbon exchange is slower. Approximately 28% of the original CO2 pulse remains in the atmosphere after 500 years. Very Slow Exchange: The slowest part of the carbon cycle involves moving CO2 into the rock reservoir, which occurs over thousands to tens of thousands of years. About 14% of the original CO2 pulse persists after 10,000 years. The implications of these timescales are profound: Long-Term Impact: The numbers reveal that the impact of our actions today in terms of releasing CO2 will have far-reaching consequences for the Earth's climate system. Even though a substantial portion of a CO2 pulse is removed relatively quickly, a significant fraction remains in the atmosphere for centuries and even millennia. This means that the warming effect associated with that CO2 persists over these long timescales. Legacy Emissions: Our current emissions are not just affecting our generation or the immediate future; they will have a lasting legacy. As you pointed out, even after the Paleocene-Eocene Thermal Maximum (PETM), a period of significant warming approximately 56 million years ago, it took hundreds of thousands of years for the carbon to be removed and for the warming to dissipate. This highlights the long-term commitment we have to the consequences of our carbon emissions. Mitigation Urgency: The knowledge of these timescales underscores the urgency of mitigating CO2 emissions. Actions we take now to reduce emissions can have a significant impact on the amount of CO2 released into the atmosphere and the associated long-term climate consequences. Slowing down the rate of CO2 increase is crucial to limiting future warming.

What is the general structure of global climate models? How do we use these models to anticipate climate effects? Can these models tell us what future emissions will be?

Grid System: The Earth's surface is divided into a multi-layer grid, often using latitude, longitude, and elevation as coordinates. Each grid cell represents a specific region on the Earth's surface --> Within each grid cell, GCMs simulate a wide range of physical processes that occur in the Earth's climate system. These processes include radiative forcing (RF), temperature/heat transfer, humidity, evaporation, precipitation, plant growth, melting and freezing of ice, cloud formation, ocean and air currents, and many more. The models account for the interactions between these processes. Comparative Analysis: GCMs are run under different emissions scenarios to create a range of potential future climate outcomes. By comparing the results of these simulations, scientists can assess how various climate variables will change as emissions rise. This allows for the examination of potential impacts on temperature, precipitation patterns, sea-level rise, and other climate-related factors. Predicting Climate Effects: Climate models can provide valuable insights into what is likely to happen as greenhouse gas concentrations increase. These predictions include temperature increases, sea-level rise, and changes in precipitation patterns. The models offer a basis for understanding the physical consequences of climate change under different emissions scenarios. Limitations of GCMs: Future Emissions: While GCMs can anticipate climate effects based on emissions scenarios, they cannot predict with certainty what future emissions will be. The socioeconomic, political, and technological developments that drive emissions are highly uncertain. Varying Levels of Confidence: GCMs are more reliable in simulating some climate processes than others. For instance, the models can confidently predict rising temperatures and sea levels, but there is less certainty when it comes to precipitation patterns or specific weather events like hurricanes. Scenario-Based Predictions: GCMs do not provide a single prediction of the future climate but offer multiple scenarios. These scenarios are based on different assumptions about future emissions and socioeconomic pathways. They offer a range of possible outcomes.

How long does methane remain in the atmosphere? (For concreteness, you can interpret this question as "How long does it take to remove 70 percent of a methane "pulse" from the atmosphere?") What are some important implications of these numbers?

Methane, a potent greenhouse gas, has a considerably shorter lifetime in the atmosphere compared to carbon dioxide (CO2). To remove 70% of a methane "pulse" from the atmosphere, it takes approximately 12.4 years. The implications of methane's shorter atmospheric lifetime are significant: Rapid Response: Unlike CO2, which can persist in the atmosphere for centuries to millennia, methane has a much shorter lifetime. This means that when we reduce methane emissions, we can expect a relatively rapid response in terms of cooling the planet. If we take actions to lower methane emissions, we can see the effects within a few decades, making it an important short-term priority for mitigating climate change. High Global-Warming Potential: Although methane emissions are smaller in quantity compared to CO2 emissions, their impact on global warming is disproportionately higher. Methane is about 32 times more effective at trapping heat in the atmosphere than CO2 over a 20-year period. This makes it a potent contributor to short-term warming, which is why reducing methane emissions is crucial for immediate climate action. Addressing Near-Term Climate Goals: Given its short atmospheric lifetime and high global-warming potential, addressing methane emissions is particularly important for achieving near-term climate goals. By reducing methane emissions, we can achieve a relatively quick reduction in the rate of global warming, which can be essential for avoiding the most severe climate impacts in the coming decades. Complementing CO2 Reduction: While addressing CO2 emissions is crucial for long-term climate stability, addressing methane emissions provides an opportunity to complement these efforts. Combining reductions in both CO2 and methane emissions is a balanced strategy for addressing climate change in the short and long term. In summary, the relatively short atmospheric lifetime of methane makes it a prime target for immediate climate action. Reducing methane emissions can lead to quick cooling effects, which can help mitigate the near-term impacts of climate change and complement efforts to reduce CO2 emissions for long-term climate stability.

Military Bases and Resources: Climate change can directly threaten military installations and resources. Rising sea levels, for example, can inundate coastal bases and damage infrastructure, making them less effective or even unusable. More frequent and severe wildfires can encroach on military training areas and storage facilities, posing significant risks. Thawing permafrost can destabilize the ground and structures in Arctic regions, impacting military operations. These threats require costly investments to adapt and safeguard these assets, diverting resources from other defense priorities. Refugee Crises and Geopolitical Tensions: Climate change-induced disasters, such as hurricanes, droughts, and sea-level rise, displace populations from their homes. As people migrate to escape the impacts, it can lead to refugee crises. This can strain the resources and capacities of host countries and trigger geopolitical tensions. Disputes can arise over responsibility for climate refugees, and the pressure on nations to accommodate them can lead to strained international relations. Interstate Tensions: Climate change can exacerbate tensions between countries over vital resources. Competition for freshwater sources, exacerbated by changing precipitation patterns, can lead to conflicts over access and rights. Additionally, minerals like lithium and cobalt, essential for clean energy technologies, may become scarcer, intensifying competition for these resources. As the Arctic ice melts, access to the region's resources and shipping routes becomes a point of contention. Disagreements over emissions reductions and climate policies can create diplomatic tensions, particularly when countries prioritize their national interests over global climate action. Political Instability: Climate change contributes to political instability within nations. Heatwaves and droughts can lead to crop failures and food shortages, which can trigger civil unrest and protests. In some cases, these events may even escalate into conflicts. Natural disasters, exacerbated by climate change, can overwhelm governments and divert resources away from development and stability efforts. Long-term political instability can hinder a country's capacity to ad

Pros and Cons of SRM

PRO Temperature Reduction: SRM has the potential to reduce global temperatures - we have seen it done before. 3. Cost and Implementation: SRM is considered cost-effective compared to many other climate mitigation approaches. The estimated cost of SRM is relatively low, making it economically feasible. 4. Offset to Greenhouse Gases: can act as a temporary offset to the effects of greenhouse gases. It can provide a buffer period during which efforts to reduce greenhouse gas emissions can take effect. This time can be valuable for implementing long-term climate change solutions. CON 5. Termination Surge: A major concern with SRM is the concept of a "termination surge." If SRM were to be abruptly halted, it could lead to a sudden spike in temperatures. This is because greenhouse gases continue to accumulate, and the sudden removal of the cooling effect from SRM would result in rapid warming. 6. Unintended Consequences: Manipulating the Earth's albedo can have unintended consequences for regional climates and weather patterns. For example, changes in precipitation patterns, shifts in monsoons, or altered wind patterns may occur, impacting local and global weather systems. Ethical and Political Challenges: Decisions regarding when, where, and how to implement SRM techniques are fraught with ethical and political complexities. Who gets to decide how SRM is used, and how is it regulated on a global scale? Countries could have conflicting interests, leading to international disputes. 8. Narrow Focus on Temperature: SRM primarily addresses temperature reduction and does not tackle other critical aspects of climate change, such as ocean acidification, sea level rise, and ecosystem disruptions. As a result, it does not provide a comprehensive solution to climate change's multifaceted challenges. In summary, SRM has its merits, particularly in its potential to cool the Earth and its cost-effectiveness. However, it comes with significant drawbacks, such as the potential for unintended consequences, the risk of abrupt termination, and complex political and ethical issues. Many experts view SRM as a supplementary measure to mitigate climate change, rather than a standalone solution. Research into its impacts and gover

What are some pros and cons of CDR - carbon dioxide removal

Pros of Carbon Dioxide Removal (CDR): Addressing Historical Emissions: CDR can help compensate for historical emissions that have already accumulated in the atmosphere. It provides a means to "clean up" the excess CO2 that has been released over the years. Long-Term Carbon Sequestration: Many CDR methods, such as reforestation, afforestation, and enhanced weathering, involve capturing and storing carbon in natural or geological reservoirs. This sequestration can be long-lasting, effectively removing CO2 from the atmosphere. Flexible and Scalable: CDR methods can be implemented on various scales, from local projects like reforestation to large-scale operations like direct air capture (DAC). This flexibility allows for a range of approaches tailored to specific needs. Complements Mitigation: CDR serves as a complement to emission reduction strategies (mitigation). It can help offset emissions that are challenging to eliminate completely, such as those from certain industrial processes. Cons of Carbon Dioxide Removal (CDR): Technological Maturity: Many CDR techniques are not yet technologically mature or economically viable at the scale required to make a significant impact. Developing and deploying these technologies may take considerable time and resources. Land and Resource Use: Certain CDR methods, like afforestation and bioenergy with carbon capture and storage (BECCS), require substantial land and resources. This can lead to competition for land that might be used for food production, biodiversity conservation, or other purposes. Permanence and Leakage: Ensuring the long-term permanence of carbon sequestration in geological reservoirs or forests can be challenging. Leakage of stored carbon back into the atmosphere is a risk, especially in the face of changing environmental conditions. Environmental and Ecological Impacts: Some CDR methods, like BECCS and large-scale afforestation, could have unintended consequences for ecosystems and biodiversity. It is crucial to carefully consider potential impacts on local environments. Energy Requirements: DAC, one of the more promising CDR technologies, demands a significant amount of energy. Depending on the source of this energy, it could contribute to additional g

How do sulfate aerosols cool the planet? What are some examples of this? What are some policy implications?

Reflecting Solar Radiation: Sulfate aerosols are tiny particles that are released into the atmosphere, primarily through the combustion of fossil fuels, especially coal. These particles have a high albedo, meaning they reflect incoming solar radiation back into space. When these aerosols are present in the atmosphere, they scatter and reflect sunlight, preventing a portion of it from reaching the Earth's surface. This reduces the amount of solar energy that warms the planet, resulting in a cooling effect. 2. Cloud Formation and Albedo: Sulfate aerosols can act as cloud condensation nuclei. They provide surfaces on which water vapor can condense to form clouds. These clouds, often referred to as "sulfate aerosol clouds" or "sulfate clouds," tend to have a higher albedo compared to clear skies. This means they reflect more sunlight and, in turn, reduce the amount of solar energy absorbed by the Earth's surface. Implications: Air Quality vs. Climate: Sulfate aerosols have a dual nature in environmental discussions. While they have a cooling effect on the climate, they are also associated with negative impacts on air quality and human health. Policies to reduce emissions of sulfur dioxide (SO2), a precursor to sulfate aerosols, are often implemented to improve air quality and public health. Climate Implications: The presence of sulfate aerosols in the atmosphere partially offsets the warming caused by greenhouse gases. This cooling effect is a double-edged sword. It suggests that efforts to reduce sulfate aerosol emissions (and thus improve air quality) could inadvertently lead to further warming if not accompanied by significant reductions in greenhouse gas emissions. Balancing Act: Balancing policies to reduce sulfate aerosol emissions with the need to mitigate climate change is a complex challenge. It underscores the importance of comprehensive climate policies that consider the interplay of various pollutants and their impacts on both climate and human well-being. In summary, sulfate aerosols cool the planet by reflecting solar radiation and altering cloud properties. While they have a temporary cooling effect, they come with air quality and health concerns.

How do the solar constant (S), albedo (α) and atmospheric layers (n) relate to a planet's temperature (T)?

Solar Constant (S): An increase in the solar constant (S) leads to an increase in a planet's temperature (T). This is because a higher solar constant means that more solar energy is received by the planet. The greater influx of energy results in higher energy input (Ein), leading to elevated temperatures. Albedo (α): An increase in albedo (α) leads to a lower temperature (T) on a planet. Albedo represents the reflectivity of the planet's surface. A higher albedo means that a larger portion of incoming solar radiation is reflected back into space, reducing the amount of energy absorbed by the planet. As a result, the planet's surface temperature is lower. Atmospheric Layers (n): An increase in the number of atmospheric layers (n) contributes to a higher planet's temperature (T). This is because an increase in the number of atmospheric layers typically indicates a thicker and more complex atmosphere. A thicker atmosphere, especially if it contains greenhouse gases (GHGs), enhances the greenhouse effect, trapping more heat near the planet's surface. This leads to elevated temperatures. In summary, these relationships can be expressed as follows: S is directly proportional to T: An increase in S leads to a corresponding increase in T. α is inversely proportional to T: An increase in α results in a decrease in T. n is directly proportional to T: An increase in n, especially when it involves the presence of greenhouse gases in the atmosphere, leads to a higher T. Implications : controlling the number of atmospheric layers (i.e., greenhouse gas concentrations) and managing albedo (e.g., through land use and climate engineering) are important considerations for addressing climate change and temperature regulation.

Why do the relative temperatures of Mercury, Venus, Earth and Mars make sense, given what we know about their solar constants, albedos and atmospheres?

Solar Constant (S): The solar constant represents the amount of solar energy received per unit area at the outer atmosphere of a planet. It is a key factor in determining the planet's temperature. Mercury: Mercury receives a higher solar constant compared to other planets because it is closer to the Sun. However, despite this high solar constant, its temperature is not as extreme as Venus due to the lack of a substantial atmosphere to trap heat. Venus: Venus also receives a high solar constant but has a much thicker atmosphere compared to Mercury. This thick atmosphere, primarily composed of carbon dioxide (CO2), traps heat through the greenhouse effect, leading to extreme surface temperatures. Earth: Earth's temperature is moderated by its atmosphere and albedo. It receives a moderate solar constant, and the presence of greenhouse gases in the atmosphere helps maintain a habitable climate. Mars: Mars, being farther from the Sun, receives a lower solar constant. Its thin atmosphere does not trap heat effectively, resulting in much colder surface temperatures. Atmosphere: Venus: Venus has an extremely thick and primarily CO2-based atmosphere. This dense atmosphere contributes significantly to its high surface temperature by trapping heat. The powerful greenhouse effect on Venus is a result of this thick atmosphere. Mercury: Mercury's atmosphere is extremely thin, almost negligible, and does not contribute to trapping heat. This is why, despite a higher solar constant, its surface temperature can vary widely, with very hot days and extremely cold nights. Mars: Mars has a thin atmosphere composed mainly of carbon dioxide. The thin atmosphere is not effective at trapping heat, and the low solar constant due to its greater distance from the Sun results in cold surface temperatures. Earth: Earth's atmosphere is composed of various gases, including greenhouse gases like carbon dioxide and water vapor. This atmosphere helps to moderate temperatures by trapping some heat while allowing the right amount of solar radiation to reach the surface, maintaining a habitable climate.

Dessler shows that a planet with a one-layer atmosphere is warmer than one with no atmosphere. Why? Why does the addition of more layers warm the planet even further?

The reason a planet with a one-layer atmosphere is warmer than one with no atmosphere is due to the greenhouse effect. This effect results from the interaction between the planet's surface and the atmosphere, which affects the energy balance of the planet. The addition of more layers of atmosphere further warms the planet for the following reasons: Greenhouse Effect with One Layer of Atmosphere: In a one-layer atmosphere, the greenhouse effect is already at work. Solar radiation from the Sun passes through the atmosphere and heats the planet's surface. The surface, in turn, emits infrared radiation back into the atmosphere. Some of this emitted infrared radiation is absorbed and re-radiated by greenhouse gases in the atmosphere, such as carbon dioxide and water vapor. This process traps heat, preventing some of the infrared radiation from escaping directly into space. As a result, the planet's surface remains warmer than it would be without an atmosphere. Addition of More Atmosphere Layers: When more layers of atmosphere are added, the greenhouse effect is further enhanced. Each layer of the atmosphere interacts with the one below it, increasing the trapping of infrared radiation. This creates a more effective "blanket" of greenhouse gases. The additional layers increase the reabsorption and re-emission of infrared radiation, effectively preventing more heat from escaping into space. This leads to a further increase in the planet's surface temperature. Energy Balance: To maintain an energy balance, a planet with an atmosphere must emit radiation (heat) to space that equals the amount of solar energy it absorbs. With a one-layer atmosphere, the surface of the planet is responsible for emitting the necessary amount of energy to maintain this balance. This requires the surface to be warmer than it would be without an atmosphere. As more layers of atmosphere are added, the greenhouse effect becomes more efficient at trapping heat. This means that the surface has to become even warmer to radiate enough energy into the atmosphere to maintain the energy balance for the entire system. In essence, each layer of the atmosphere adds another level of greenhouse effect, making it increasingly effective at keeping the

Quiz 1 : Compared with the climatic changes of the last 70 million years, recent (i.e., the last two centuries) climate change has been a) relatively large b) about the same c) relatively small

c) relatively small

Quiz 3 : Which of the following is NOT a concern about solar radiation management (SRM)? a) It could have unanticipated effects on weather patterns b) Stopping it suddenly could lead to a "termination surge" (a rapid spike in global temperatures) c) It could lead to political conflict d) We don't know if it would work

d) We don't know if it would work

Quiz 3 : As global temperatures continue to rise, we expect that : a) the oceans will become more acidic b) wildfires will become more frequent and severe c) heat waves will become more frequent and severe d) many people will have to move to flee climate disasters e) All of the above

e) All of the above

Quiz 1 : Which of the following is NOT part of the normal scientific process? a) Hypothesis testing b) Peer review c) Replication d) Testing additional implications of a theory e) Cherry picking data

e) Cherry picking data

Quiz 1 : Which of the following measures represents a temperature anomaly? a) In 2022, the average global temperature was 15.5 C b) In 2022, the average global temperature was 60.0 F e) In 2022, the average global temperature was 0.9 C above the 20th-century average f) All of the above

e) In 2022, the average global temperature was 0.9 C above the 20th-century average

What is solar radiation management? What are some pros and cons?

geoengineering approach: deliberately modifying the Earth's albedo, or its reflectivity, in order to reduce the amount of solar radiation reaching the planet's surface. The primary goal of SRM is to cool the Earth and counteract the warming caused by the accumulation of greenhouse gases (GHGs) in the atmosphere. Sulfate Aerosols and Cooling: SRM strategies often involve the injection of sulfate aerosols, such as sulfur dioxide, into the upper atmosphere. These aerosols reflect sunlight back into space, reducing the amount of solar radiation that reaches the Earth's surface. This mimics the cooling effect observed after volcanic eruptions when sulfur dioxide is released into the stratosphere. The temporary Pause in temperature rise during 1940-1980 was largely due to anthropogenic sulfate aerosols.

extra - ipcc and climate change

he Intergovernmental Panel on Climate Change (IPCC) plays a pivotal role in advancing our understanding of climate change and its impacts. Here's an expanded explanation of the significance and process of IPCC reports: Global Scientific Collaboration: The IPCC is a global body that brings together climate scientists, experts, and researchers from diverse backgrounds and regions. This international collaboration ensures that the IPCC reports are comprehensive, drawing on a wealth of knowledge and expertise. This collaboration is vital because climate change is a global challenge that requires a collective response. Comprehensive Assessment: The IPCC conducts regular comprehensive assessments of the state of climate science. These assessments encompass a wide range of topics, including the physical science of climate change, impacts on ecosystems and societies, adaptation and mitigation strategies, and more. This breadth allows for a holistic understanding of climate change. Synthesis of Evidence: IPCC reports are not just a collection of scientific papers. They serve as a synthesis of the latest scientific evidence, providing a clear and accessible overview of the current state of climate knowledge. This synthesis is crucial for policymakers, as it condenses complex scientific findings into understandable and actionable information. Scientific Consensus: IPCC reports represent a consensus of the scientific community. The findings and conclusions are not based on the opinion of a single researcher or a particular institution but rather on the collective judgment of experts. This consensus-based approach lends credibility to the reports and ensures that they reflect the most widely accepted scientific understanding. Assessment Process: The assessment process is rigorous and transparent. It involves multiple stages, including scoping, drafting, review, and approval. During the review phase, the reports are subjected to scrutiny by experts, governments, and organizations, which helps identify and rectify any potential errors or biases. This process ensures the highest level of accuracy and objectivity. Policy Relevance: IPCC reports are not only for the scientific community; they are highly relevant to policymaker

You come across an article that says "Right now the world is on track to warm by 2.5⁰C by 2100." Is this forecast set in stone (i.e., is it guaranteed to happen)? What developments could cause this forecast to be incorrect?

he forecast that "the world is on track to warm by 2.5⁰C by 2100" is not set in stone and is subject to several uncertainties and variables. Climate forecasts, including temperature projections, are based on a combination of climate models and assumptions about future emissions. Here's why this forecast could be incorrect: Uncertainty in Emissions: The forecast relies on assumptions about future greenhouse gas emissions (e.g., CO2, methane) and the implementation of emissions reduction strategies. If global emissions follow a different trajectory than the one assumed, the temperature increase could be higher or lower than predicted. Unforeseen Technological Advancements: Climate models are based on our current understanding of technology and its potential. If significant technological breakthroughs occur, such as the rapid development and deployment of carbon capture and storage (CCS) technologies, it could alter the emissions pathway and lead to a different temperature outcome. Behavioral and Policy Changes: Human actions and policy decisions play a crucial role in emissions reductions. Shifts in public behavior, consumer choices, government policies, and international agreements can influence emissions trajectories. For example, ambitious climate policies, increased adoption of renewable energy, or a global commitment to decarbonization could deviate from the assumed emissions pathway. Natural Variability: Climate systems exhibit natural variability, and this can influence short-term climate trends. Natural phenomena like volcanic eruptions, solar activity, and El Niño events can temporarily influence temperature patterns, creating fluctuations that may temporarily mask or exaggerate the long-term warming trend. Unknown Climate Feedbacks: There may be climate feedback mechanisms that are not yet fully understood or included in climate models. These feedbacks could either amplify or mitigate the projected temperature increase. Tipping Points and Irreversible Changes: The forecast assumes a relatively linear trajectory of warming. However, the existence of potential tipping points in the climate system could lead to abrupt and unpredictable changes that are not captured in linear projections. Global Action

What are some drawbacks of an adaptation-only response to climate change?

incomplete Solutions: Adaptation measures do not prevent climate change but only minimize its impacts. They provide a temporary solution to specific problems caused by climate change but do not address the root cause, which is the increase in greenhouse gas emissions. As a result, they are limited in their ability to protect against all negative consequences. Costly: Adaptation measures can be expensive, especially when dealing with large-scale infrastructure projects like sea walls, flood barriers, or relocation of communities. The cost of adaptation can strain government budgets and hinder economic development in vulnerable regions. Resource Inequity: An adaptation-focused approach can exacerbate global and local inequalities. Wealthier countries and communities often have greater resources to implement effective adaptation measures, while poorer regions may struggle to cope. This can lead to disparities in vulnerability and resilience. Economic Loss: Relying solely on adaptation may

We know that continued climate change will destroy a lot of coral reefs. If we want to incorporate this fact into the SCC, what do we need to do?

incorporating the impact of continued climate change on coral reefs into the Social Cost of Carbon (SCC) would require estimating the economic damages associated with the loss of coral reefs and then including these damages in the SCC calculation Estimate the Economic Damages: researchers would need to assess the potential economic damages caused by the destruction of coral reefs. This could include factors like lost revenue from tourism and fisheries, reduced coastal protection, and the loss of biodiversity and ecosystem services provided by coral reefs. Consider Different Climate Scenarios: The SCC is typically calculated for various emission scenarios and timeframes. Researchers would need to factor in different climate change scenarios and the corresponding impact on coral reefs. This would involve projecting the extent of coral reef destruction under different emissions trajectories. Integrate Damages into the SCC: The estimated economic damages from coral reef loss would then be integrated into the SCC calculation. This would involve adding the damages caused by coral reef destruction to the total damages from climate change. The SCC calculation would now include the economic costs associated with these damages per tonne of CO2 equivalent emissions. Determine the Appropriate Discount Rate: As with the SCC calculation in general, the choice of an appropriate discount rate is essential. The discount rate affects how future damages are valued in present terms. It would also apply to the damages related to coral reef loss. Apply the chosen discount rate to the future costs associated with coral reef degradation. This involves reducing the future costs to their present value.

Why is the Earth's equator warmer than its poles?

lecure 2 - slide 11 - Near the equator, the angle at which sunlight strikes the Earth's surface is more nearly perpendicular. This means that the same amount of solar energy is concentrated over a smaller area, resulting in higher solar insolation (incoming solar radiation) at the equator. At the equator, sunlight strikes the Earth's surface more directly throughout the year. This leads to a higher angle of incidence, which means that a smaller portion of incoming solar radiation is reflected back into space. More solar energy is absorbed at the equator compared to regions at higher latitudes. The amount of solar energy received at any location on Earth depends on the angle of incidence. When sunlight is directly overhead (perpendicular to the surface), it is concentrated and more intense. Conversely, as you move away from the equator toward the poles, the angle of incidence becomes shallower. Equatorial regions, located near the Earth's equator, receive more solar energy because t

What is the discount rate? Why do we need to know it to calculate the SCC?

represents the rate at which future costs and benefits are converted into present values.The degree to which we discount the future relative to the present. It convert future climate damages and costs associated with carbon emissions into their present value. r = 0: the future matters as much as the present r = 100: the future doesn't matter at all Time Value of Money: The discount rate accounts for the time value of money, recognizing that a dollar today is worth more than a dollar received in the future. This is because money received now can be invested or used to generate returns, making it more valuable than the same amount received later. Conversely, future costs and benefits are discounted to their present value. A higher discount rate reduces the present value of future climate damages, making it appear as if those damages have lower economic significance. Conversely, a lower discount rate increases the present value of future damages, highlighting their greater economic importance. A lower discount rate reflects a concern for the well-being of future generations and acknowledges the importance of inter-generational equity in addressing climate impacts. It suggests that we should be willing to incur higher present costs to mitigate carbon emissions for the benefit of future generations.

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