ENV 101 Chapter 9 (Climate Change and Global Warming)

Climate Change

- Change in the statistical properties of the climate system when considered over periods of decades. - Shows that Earth's climate is dynamic. - Over hundreds of thousands of years, the global climate has varied in response to regular changes in Earth's orbit that influence the amount of sunlight it receives. - During the past 10,000 years: Earth has grown warmer, but with notable ups and downs. - In the past 1,000 years: The climate has warmed, cooled, and then warmed again.

What factors contributed to the alternating glacial and interglacial periods over the past 800,000 years?

- Changes in Earth's orbit that influence the amount and distribution of solar distribution. - Earth cycled between colder and warmer periods. - Cold period brought severe glaciations. - Huge glaciers between 1,000 and 3,000 m (3,300-10,000 ft) thick spread across vast areas of North America and Eurasia. - Changes in ocean currents could have altered the patterns of heat transfer around the globe, leading to greater cooling toward the poles. - Changes in the chemical composition of Earth's atmosphere.

Increased Rainfall (The Consequences of Global Warming)

- Rainfall has increased significantly in eastern North and South America, as well as in most parts of Europe and Asia. - There has been a worldwide increase in the frequency of rainstorms that result in flooding, even in areas where total annual rainfall has declined. - In regions in which rain is highly seasonal, such as sub-Saharan Africa, global warming appears to be changing the length of wet and dry periods. This is a matter of special concern because food production depends on the length of wet seasons. Growing seasons are expected to become shorter over most of sub-Saharan Africa.

Describe two factors that influence variations in annual temperature anomalies from one geographic location to another.

- Regional variation on land: Annual temperature anomalies vary considerably from location to location. In much of the Arctic, temperature anomalies have exceeded 2 degrees Celsius (3.6 degrees Fahrenheit). These higher than average temperature anomalies are related to circulation patterns in the troposphere and ocean currents, which move heat from the equator toward the poles. This magnifies temperature change in the polar regions. Therefore, it's no surprise that some of the effects of global warming have been most pronounced in polar regions. - Because continental regions heat up more quickly than nearby oceans, temperature anomalies are generally higher over the interior of continents, such as North America and Eurasia. In a few regions, such as over parts of the Gulf of Alaska and the ocean around Antarctica, temperature anomalies are actually negative. In these areas cooling circulation and upwelling of cold water.

Why are some places becoming drier if rainfall is increasing?

- Some places are becoming increasingly warmer. - Global warming is influencing the drought cycles. Water off the west coast of South and Central America are cold, drought is more common in the southwestern United States.

Droughts (The Consequences of Global Warming)

- Sub-Saharan Africa, the Mediterranean region, and western North America have been drier. - Since 1970, longer and more intense droughts, as measured by decreased precipitation and higher temperatures, have affected wide areas of the tropics and subtropics. - There is evidence that global warming is influencing drought cycles. For example, the El Niño/La Niña/Southern Oscillation is caused by changes in the temperature of surface waters in the equatorial Pacific Ocean. When waters off the west coast of South and Central America are cold, drought is much more common in the southwestern United States.

What is the role of the IPCC in the development of international climate policy?

- The IPCC is a scientific body that synthesizes evidence on climate change from within the scientific community. - The IPCC released a series of reports that emphatically restated its earlier conclusion that Earth's atmosphere is warming. - The report also concluded that global warming is a direct consequence of human activities that are increasing emissions of greenhouse gases. - These reports stated that some amount of future warming is inevitable and that global community will need to take steps to adapt. - This strong statement and the consensus of IPCC members provide a solid foundation for policy development in the international community.

What is responsible for the seasonal changes in CO2 concentrations observed in data from the Mauna Loa Observatory?

- The Keeling Curve - Charles D. Keeling's data revealed clear seasonal cycles in the concentration of CO2, which were related to the changes in the net productivity of ecosystems during summer and winter. - CO2 increasing up and down each year. - The curve reveals during summer months there is a decrease in CO2 concentrations because the plants absorb the carbon and release oxygen. - And in winter months the CO2 concentrations are higher because there is no plants to absorb the carbon.

What are the key features of the Kyoto Protocol?

- The Kyoto Protocol set an overall goal of reducing CO2e emissions to 5% below their 1990 levels by 2010. - For developed countries, the targets for reducing emissions were based on historic levels of emissions. - No targets were set for developing countries (including China and India) because of fears that emissions caps would inhibit their economic development. Instead, targets for developing countries would be added to the protocol at an unspecified later date. - Greenhouse gas emissions in developed countries increased on average by 5.6%; U.S. emissions increased by 3.4%.

How does the Paris agreement differ?

- The Kyoto Protocol: The treaty was a necessary first step in moving greenhouse gas emissions to sustainable levels. Focused on developing countries. Didn't set targets for developing countries because of fears that emission caps would inhibit their economic development. - The Paris Agreement: The agreement calls for zero net anthropogenic greenhouse emissions to be reached by the second half of this century. Focuses on all countries to agree to reduce their greenhouse gas emissions.

Pleistocene epoch

- The cold periods are typically referred to as glacial periods, or sometimes ice ages. - The periods of intervening warmth then are referred to as interglacial periods. - Each of these cycles of cold and warm lasted about 100,000 years. - Scientists call this time of alternating cold and warm periods this.

Explain why many world leaders view adaptations to global warming as an environmental justice issue.

- The conditions of global warming like droughts, floods, heat, storms, and rising sea level effects poor countries and developing countries.

Temperature anomaly

- The difference between each year's average temperature and the benchmark. - A positive anomaly indicates a year that is warmer than the benchmark. - A negative anomaly represents a year that is cooler than the benchmark.

Why does the loss of ice and snow cover accelerate global warming?

- The loss of ice and snow cover accelerates global warming because the rate of melting exceeds the rate of ice formation. - Earth's glaciers are retreating and sea level is rising. - Causes the Earth's surface to absorb more energy from the sun and become warmer.

Global warming potential (GWP)

- The measure of an individual molecule's long-term impact on atmospheric temperature.

What is the Anthropocene?

- The period during which human activity has been the dominant influence on Earth's environment and climate. - Holocene period: The past 10,000 years. Earth in warm interglacial period. Climates were especially warm between 9,000 and 5,000 years ago. Then, average temperatures became a bit cooler 5,000 to 1,000 years ago. Climates shifted in various regions. - Medieval Warm Period: A.D. 1000-1300. During this time, average global temperatures increased by 0.2-0.5 degrees Celsius. - Little Ice Age: A.D. 1400-1500. Just as the Renaissance was blossoming in Europe, a cold and wet period set in over the Northern Hemisphere. Once again, mountain glaciers in Europe and North America grew larger and advanced downslope.

Greenhouse effect

- The trapping of heat in the troposphere by greenhouse gases. - Greenhouse gases in the the troposphere are warmed, as light is absorbed and then released as infrared radiation from Earth's surface. - Because the tropopause tends to prevent the mixing of gases in the troposphere with the gases in the stratosphere, the heat gets trapped.

Rising Sea Level (The Consequences of Global Warming)

- Thermal expansion and meltwater from glaciers are increasing ocean volume. - Over the past 50 years, sea level has risen about 9 cm (3.5 in.); that is an average rate of 1.8 mm (0.07 in.) per year. - Two factors are responsible for this change: The expansion of water as it warms and melting ice. - The effects of rising sea level are already being felt in many coastal areas. Shorelines and barrier islands are eroding. This rise could dramatically alter coastlines and cause many low-lying ocean islands to disappear.

What are the four factors that cause CO2 emissions to differ widely among countries?

- Various human activities contribute differing amounts to total greenhouse gas emissions. 1) Electricity: Most of the electricity we use is generated by burning fossil fuels, largely coal and natural gas, so it's not surprising that electricity generation produces the largest portion of emissions. 2) Industry: Industrial processes are next in importance. These include activities such as the manufacture of concrete, which is responsible for 30-40% of all industrial emissions. Involves heating limestone and other materials to 2,550 degrees Fahrenheit. This requires burning over 180 kg (400 lbs) of coal for each ton of concrete. 3) Agriculture: Agriculture is the source of about 12.5% of greenhouse gas emissions, primarily in the form of CH4 and N2O from livestock and the use of fertilizer. 4) Industrialized vs. Developing Countries: In industrialized countries, the vast majority of greenhouse gas emissions comes as CO2 from burning fossil fuels. However in many countries, deforestation and agriculture are the predominant sources. In Brazil, emissions are associated with deforestation. Developing countries like China and India's per capita emissions have increased.

How are we/how will we have to adapt to global warming in the following areas:

1) Drought: Drier conditions and extended droughts are most likely to occur in regions where water is already in short supply. Agriculture in arid regions often depends irrigation. Urban areas will also be affected. Many cities have already begun to meter water and restrict water use. Many are also working to minimize leakage and evaporation from water supply systems. In U.S., many states are requiring cities to implement plans for sharing water among jurisdictions. 2) Floods: Adaptions in agriculture may include changes in crop varieties and planting methods and the use of technologies to aerate soil and prevent erosion caused by increased runoff. Increased rainfall may require the redesign of storm sewers and drainage systems. 3) Heat: Adaptations to hotter weather may involve improved building design and heat control. More important is the need for effective programs to protect vulnerable populations like the poor and elderly. 4) Storms: Such measures might include requiring water resistant construction, strengthening levees, and restoring wetlands that once protected coastal areas. 5) Sea level: Adaptation to rising sea level has already begun in the low-lying areas of the Netherlands. There, pumping systems, canals, and dikes are being upgraded to protect agriculture and urban centers.

Describe how humans increased the abundance of certain greenhouse gases in the atmosphere:

1) Fossil Fuel Burning: Increases in anthropogenic greenhouse gas emissions came with the burning of fossil fuels: first coal, then petroleum and natural gas. Their combustion releases greenhouse gases, especially CO2. 2) Deforestation: Scientists estimate that human land use adds CO2 to the atmosphere. Fires associated with deforestation and agriculture also emit methane (CH4) and nitrous oxide (N2O). 3) Synthetic Greenhouse Gases: Release chlorofluorocarbons (CFC) compounds. Which are used as refrigerants, cleaning solvents, and fire retardants and the manufacture of plastic foam products.

Describe two policies aimed at reducing CO2 emissions that have been enacted in the US.

1) The Corporate Average Fuel Economy (CAFE): The U.S. government regulates the mileage of automobiles. CAFE requires that the average gasoline mileage of all the cars made by a manufacturer meet a certain standard. The current standard for automobiles is 27.5 miles per gallon; this will increase to 40.1 miles per gallon by 2021. 2) Clean Power Plan: The EPA now monitors annual CO2 emissions from transportation, industry, and utilities. Which established greenhouse gas emission standards for new, modified, and reconstructed power plants. It also established a program aimed at working with states to develop standards for limiting emissions from existing power plants.

Describe two factors contributing to the global rise in sea level.

1) The expansion of water as it warms: The ocean absorbs much of Earth's heat. This increase in temperature causes liquid water to expand slightly. In the huge volume of the ocean, its effect is significant. 2) Melting ice: The net influx of water from the continents into the oceans, as mountain glaciers and ice sheets melt, also contribute to the rising sea level. Sea level may rise. This rise could dramatically alter coastlines and cause many low-lying ocean islands to disappear.

What factors go into calculating a molecule's global warming potential (GWP)?

1) Their capacity to absorb infrared light and retain heat. 2) The length of time they stay in the atmosphere, or their atmospheric residence time.

Pascal and Socolow Propose Action To Mitigate Global Warming In Four Areas:

1) Transportation efficiency: A single car traveling 10,000 miles using 30 miles per gallon of gas puts 3.6 tons of CO2e into the atmosphere each year. If fuel efficiency were doubled to 60 miles per gallon, the emissions from each auto would be halved. Improved hybrid and diesel technologies, as well as lighter construction materials, have already increased mileage significantly. 2) Transport conservation: In terms of the energy used per person, trains, buses, and other forms of public transportation are far more efficient than automobiles. Investment in mass transit and urban planning to make public transportation more accessible could cut the number of miles traveled by automobiles by half. 3) Building efficiency: Buildings use energy for heating and air conditioning, heating water, lighting, and electrical appliances. Improved design and use of materials could reduce energy use and emissions considerably. 4) Efficiency in electricity production: Coal-burning power plants produce about 65% of the world's electricity and account for over 25% of its CO2e emissions. Increased efficiency in the conversion of energy in coal into electricity could equal a wedge. Could come from technologies such as high efficiency turbines.

Name four important greenhouse gases and the human activities that are most important in their production.

1) Water vapor (H2O): Water is not considered to be adding to global warming. The effect of water vapor on the temperature of the atmosphere is complicated by water's phase transitions from solid to liquid to gas. 2) Carbon dioxide (CO2): Deforestation and the burning of fossil fuels add large quantities of carbon dioxide to our atmosphere. 3) Methane (CH4): Industrial and agricultural activities. Cows and sheep: Digestive processes. 4) Nitrous oxide (N2O): Industrial and agricultural activities. Fires associated with deforestation and agriculture also emit CH4 and N2O.

Why is it difficult to measure directly the global average annual temperature?

- Because temperatures vary considerably from location to location. - It is difficult to get estimates that are not biased or uncertain.

Describe what occurs during the El Niño Southern Oscillation (ENSO).

- Changes in ocean patterns: Over a three to eight-year period, surface ocean temperatures cycle between relatively cold and warm conditions. During the cold part of the ENSO cycle, ocean currents bring cold water from the Antarctic Ocean to the equator along the west coast of South America. The upwelling of deep ocean water contributes to the cold temperature of the surface water. - The situation changes when water warmed in the western equatorial Pacific moves eastward, overriding the colder, denser water. Because the warm part of the cycle often begins around Christmas time, South American fisherman call it El Niño, in reference to the Christ child. - Alters weather patterns: ENSO affects weather conditions around the world. El Niño's warm waters feed thunderstorms and increase rainfall across the eastern Pacific Ocean and western South America. But to the east, across the Andes and in the Amazon Basin, warm, dry conditions prevail. In North America, El Niño winters are warmer than normal in the Midwest, Northeast, and Canada, but in the Southwest and Mexico, winters are cooler and wetter.

Black carbon

- Forest fires and the burning of fuelwood and charcoal release solid particles.

Greenhouse Gases (GHGs)

- Gases that efficiently capture heat. 1) Water vapor (H2O): Most abundant naturally occurring gas 2) Carbon dioxide (CO2) 3) Methane (CH4): Most concern 4) Nitrous oxide (N2O)

Why does global warming increase rainfall?

- Global warming increases rainfall because warm air holds more moisture. - Which causes more evaporation and increased change of precipitation.

Changing of Ecosystems (The Consequences of Global Warming)

- Global warming is affecting ecosystems as plants and animals respond to altered habitats. - Satellite images of Canada, New England, and the Midwest since 1980 reveal that warmer spring temperatures are causing the leaves of plants to open earlier. - On ground, scientists have observed that many species of birds are nesting and laying eggs earlier than in the past. There is still a risk that spring frosts will damage young leaves and kill nestling birds. - Milder temperatures are causing migratory birds to move to the Arctic earlier and stay in high latitudes later in the fall. This delayed departure exposes some species to fierce autumn storms as they migrate southward. - Global warming is affecting the behavior of plants and animals in both terrestrial and aquatic ecosystems. - Canadian polar bears are hunting farther inland. This results in more frequent negative interactions between bears and human communities. - North Sea codfish is failing to recover from overfishing. Apparently, the waters off Europe's coast are too warm for the plankton necessary to support juvenile cod.

Milankovitch cycles

- Idea proposed in the 1920s by Serbian mathematician-astronomer, Milutin Milankovitch. - Changes in the shape earth's orbit and tilt that cause glacial periods and interglacial periods. - These changes affect the average amount and distribution of solar radiation striking Earth's surface. - Milankovitch hypothesized that major glacial and interglacial periods had varied on a 100,000-year cycle.

What economic sectors produce the most greenhouse gas emissions? The least?

- Most greenhouse gas emissions: Industry, land use and agriculture, and electrical power generation are responsible for the generation of 70% of all greenhouse gas emissions. - The least amount of greenhouse gas emissions: Transportation, fossil fuel retrieval and processing, and buildings are responsible for the generation of 30% of all greenhouse gas emissions.

Melting Glaciers and Ice Sheets (The Consequences of Global Warming)

- Nearly 75% of Earth's fresh water is contained in various forms of ice. This includes snow cover, mountain glaciers, and the massive glaciers or ice sheets that cover most of the landmass of Greenland and Antarctica. - The total amount of frozen water depends on the rate of snowfall and ice formation relative to the rate at which it melts. In most places today, the rate of melting exceeds the rate of ice formation. - Snowpack in many mountainous regions has been shrinking, and over 80% of Earth's mountain glaciers are retreating. - Average snow cover has been steadily decreasing, especially in spring and summer months in the Northern Hemisphere.

Describe how several mitigation strategies might be employed that would result in a "sustainable future" outcome.

- Pacala and Socolow suggest that a portfolio, or combination of different activities, will produce the needed reductions. - They group stabilization wedges into five categories: efficiency and conservation, fossil fuel use, renewable energy, nuclear energy, and biostorage. 1) Efficiency and conservation: transport efficiency, transport conservation, building efficiency, and efficiency in electricity production. 2) Fossil fuel use: Changes in the use of different kinds of fossil fuels (power plants fired by natural gas) and capture of the CO2 released from their burning called carbon capture and storage (CCS) that transfers it into a form that can be permanently stored underground. 3) Renewable energy: Wind generates electricity without emitting any CO2e. Wind energy produces 4% of electricity worldwide. Solar energy is used to heat water like devices like Photovoltaic (PV) cells that convert sunlight to electrical current. Biofuels are derived from plant materials like corn and wood. 4) Nuclear energy: Rapid development of nuclear facilities can diminish CO2e emissions but controversial because of safety and risk of nuclear weapons. 5) Biostorage: Refers to actions that increase the absorption and storage of CO2 in Earth's ecosystems. We can plant trees in areas where forests are currently absent. CO2 emissions from soil could be reduced by the use of farming practices that encourage carbon storage. Like reducing soil tilling, planting cover crops to prevent erosion, and applying fertilizer more efficiently.

Describe how global warming is having a significant effect on populations of plants and animal species.

- Populations of plants: Warmer spring temperatures are causing the leaves of plants to open earlier. - Populations of animal species: Many species of birds are nesting and laying eggs earlier than in the past. Milder temperatures are causing migratory birds to move to the Arctic earlier and stay in high latitudes later into the fall. Many fish species are migrating earlier because of warmer waters. Hibernating mammals are awakening earlier than in the past as they respond to temperature cues that winter is over and spring has arrived.