Science 1101 Chapters 18 and 19

Two Primary Approaches to Carbon Pricing

(1) carbon trading and (2) carbon taxation.

Sea Level is Rising at Varying Rates Along the U.S. Coast, Putting Many Cities at Risk of Costly Damage.

Along the U.S. coast, sea level is rising at varying rates.

The Science Behind the Story: What Can We Learn from the World's Longest Ice Core?

At a remote and pristine site in Antarctica named Dome C, researchers drilled down 3270 m (10,728 ft) to bedrock and pulled out more than 800,000 years' worth of ice. Data shows that by emitting these greenhouse gases since the industrial revolution, we have brought their atmospheric concentrations well above the highest levels they reached naturally at any time in the past 800,000 years. The EPICA (European Project for Ice Coring in Antarctica) results also confirm that temperature swings in the past were tightly correlated with concentrations of greenhouse gases. Also clear from the data is that temperature has varied with swings in solar radiation due to Milankovitch cycles. The complex interplay of the Milankovitch cycles produces periodic temperature fluctuations on Earth resulting in periods of glaciation (when temperate regions of the planet are covered in ice) and in warm interglacial periods (periods between glaciations).In the recent cycles, glacial periods are long, whereas interglacial periods are brief, with a rapid rise and fall of temperature. Interglacials thus appear on the graph as tall, thin spikes. In older glacial cycles, the glacial and interglacial periods are of more equal duration, and the interglacials are not as warm. The clear relationship between greenhouse gases and temperature evident in the EPICA data suggests that if we want to prevent sudden global warming, we will need to reduce our society's greenhouse emissions.

Central Case Study: Rising Seas Threaten South Florida

At least six times a year, saltwater intrusion will bubble up from the ground and flood the streets, sidewalks, and lawns of Miami, with Miami Beach being the most affected. The floods are a relatively new phenomenon, the result of rising sea levels caused by global climate change. The world's oceans rose 20cm (8in.) in the 20th century as warming temperatures expanded seawater and caused glaciers and ice sheets to melt. All coastal cities are facing challenges from flooding and increased storms that arise from the sea level increase. Southern Florida lies on flat, porous limestone, making it especially vulnerable to flooding from the ocean. Miami alone has more than $400 billion in assets located just meters from the ocean. Despite these challenges, Miami Beach is currently undergoing a building boom, and its state-level leaders are largely in denial about climate change. Local leaders, including county commissioners and mayors have worked to build up dunes, raise building foundations, shift development inland, and stop subsidizing insurance for low-lying coastal areas. Miami itself has raised some roadways 3 feet, and is spending $400 million to install a system of pumps to remove floodwater.

Changes in the Jet Stream Can cause Extreme Weather Events

*A 2012 study revealed a potential explanation for the increase in extreme weather: *Warming has been greatest in the Arctic, weakening the intensity of the Northern Hemisphere's polar jet stream *The jet stream is a high-altitude air current that blows west to east in a curving pattern that wanders north and south *As the jet stream slow down, its north and south loops become longer, forming an atmospheric blocking pattern because it blocks the eastward movement of weather patterns *This causes all weather patterns to be held in place for longer periods of time -When Arctic warming slows the jet stream, it departs from its normal configuration (a) and goes into a blocking pattern (b) that stalls weather systems in place, leading to extreme weather events.

Natural Gas

*A gas consisting primarily of methane (CH4) and other volatile hydrocarbons -A fossil fuel consisting primarily of methane (CH4) and including varying amounts of other volatile hydrocarbons

Coal

*A hard blackish substance formed from woody organic matter compressed into a dense, solid, carbon structures. *The more coal is compressed, the denser its carbon content, and the greater its energy content per unit volume (slide 19) *Coal is extracted primarily through strip mining, subsurface mining, and mountaintop removal -A solid blackish fossil fuel formed from organic material (generally woody plant material) that was compressed under very high pressure and with little decomposition, creating dense, solid carbon structures -Organic material that is broken down anaerobically but remains moist and near the surface is called peat. As peat decomposes further, as it is buried under sediments, as heat and pressure increase, and as time passes, moisture is squeezed out and carbon compounds compress more tightly together, forming coal

Geoengineering

*A risky idea that involves taking steps to directly alter the Earth's climate *Fertilize phytoplankton to draw carbon dioxide out of their air through photosynthesis. *Design "artificial trees" that filter out carbon dioxide. *Block sunlight before it reaches the each by injecting aerosols into the upper atmosphere or deploying mirrors -Any suite of proposed efforts to cool Earth's climate by removing carbon dioxide from the atmosphere or reflecting sunlight away from Earth's surface. Such ideas are controversial and are not nearly ready to implement

International Climate Negotiations Seek a Way Forward

*A series of international conferences have convened since Kyoto, trying to design a new treaty (slide 74) *The United States, India, and China have been reluctant to commit to emissions cuts

Methane Hydrate

*A solid consisting of molecules of methane embedded in a crystal lattice of water molecules *Found in sediments in the Arctic and ocean floor -An ice like solid consisting of molecules of methane embedded in a crystal lattice of water molecules. Most is found in sediments on the continental shelves and in the Arctic

Carbon Trading

*A system where permits are traded for the emission of carbon dioxide. *The government sets a cap on the amount of pollution it will allow, then gives, sells, or auctions permits to emitters that allow them to emit a certain fraction of the total amount -A form of emission trading that focuses on the emission of carbon dioxide. In a carbon trading market, emitters buy and sell permits to emit CO2. It is one approach to carbon pricing, and gives polluters a financial incentive to reduce emissions in order to address global climate change

Precipitation is Changing

*A warmer atmosphere speeds evaporation and holds more water vapor *Precipitation has increased worldwide by 2% over the past century *Overall, some regions are receiving above average amounts of rain and snow, while others receive less. *Precipitation (June-Aug.) is projected to change for the years 2081-2100, relative to 1986-2005.

Health

*A warmer climate exposes us to many potential health hazards: *More frequent heat waves. *Respiratory ailments due to more photochemical smog. *Expansion of tropical diseases, such as malaria, into temperate latitudes. *Disease and sanitation problems from flooding of sewage treatment plants. *Injuries and drowning from worsened storms.

Fee-and-Dividend

*An alternative approach, where the government transfers the carbon tax, or "fee," a tax refund, or "dividend," given to taxpayers. -A Carbon tax program in which proceeds from the tax are paid to consumers as a tax refund or "dividend." This strategy seeks to prevent consumers from losing money if polluters pass their costs along to them -In this approach, funds the government receives from polluters through the carbon tax, or "fee," are transferred as a tax refund, or "dividend," given to taxpayers -The fee-and-dividend approach is a type of revenue-neutral carbon tax

Carbon Tax

*An alternative to carbon trading is the carbon tax on the emission of carbon dioxide or the carbon content of fossil fuels *Can be charged to producers, utilities, or motor vehicle users. *A downside is that these fees often get directly passed along to the customers -A type of green tax charged to entities that pollute by emitting carbon dioxide. Carbon taxation is one approach to carbon pricing, and gives polluters a financial incentive to reduce emission in order to address global climate change -Through carbon taxation, governments charge polluters a fee for each unit of CO2 that results from their product or action

Oil Sands (Tar Sands)

*Are layers of sand or clay saturated with a viscous, tarry type of petroleum called bitumen -Fossil fuel deposit that can be mined from the ground, consisting of moist sand and clay containing 1-20% bitumen. They represent crude oil deposits that have been degraded and chemically altered by water erosion and bacterial decomposition

Acidifying Oceans Imperil Marine Life

*As carbon dioxide concentrations in the atmosphere rise, the oceans absorb more CO2. *This makes seawater more acidic, a phenomenon referred to as ocean acidification. *As seawater becomes more acidic, carbonate ions become less available and calcium carbonate dissolves, jeopardizing marine animals that produce shells. -Animals pull carbonate ions out of seawater to build their exoskeletons of calcium carbonate *Globally, ocean chemistry has already decreased by 0.1 pH unit.

Feedback Complicates Our Predictions

*As tropospheric temperatures increase, more water should evaporate and enter the atmosphere. There are two different scenarios for how this will affect climate change: *More atmospheric water vapor could lead to more warming, causing more evaporation in a positive feedback loop *More atmospheric water vapor could enhance cloudiness, reflecting sunlight back into space and slow warming in a negative feedback loop

Paris Conference: All Nations Pledge Emission Cuts

*At the 2015 conference in Paris, nations made many strong commitments: *The U.S. planned to issue new regulations on coal-fired power plants and switch to natural gas *China pledged to cut back on coal power and establish a cap-and-trade program *Brazil promised to halt deforestation *India agreed to slow its emissions growth, reforest its land, and develop alternative energy *The Paris conference was successful, in part, because each nation brought its own set of solutions to the negotiation table *The pledges made at Paris, if upheld, would bring the world only partway to a goal of limiting global warming to 2°C -Commitments made at the 2015 Paris climate meeting would limit the global temperature increase to 3.5°C (6.3°F) by 2100. This is less than the 4.5°C (8.1°F) rise predicted in the absence of those commitments, but widely misses the formal target of limiting temperature rise to 2.0°C (3.6°F).

Greenhouse Gases Warm the Lower Atmosphere

*Atmospheric gases having three or more atoms in their molecules tend to absorb infrared radiation given off by the Earth's surface, then re-emit it back downward. -As Earth's surface absorbs solar radiation, the surface increases in temperature and emits infrared radiation, radiation with wavelengths longer than those of visible light. Atmospheric gases having three or more atoms in their molecules tend to absorb infrared radiation. -As Earth's surface absorbs solar radiation, the surface increases in temperature and emits infrared radiation (p. 30), radiation with wavelengths longer than those of visible light. Atmospheric gases having three or more atoms in their molecules tend to absorb infrared radiation. After absorbing radiation emitted from the surface of Earth, greenhouse gases re-emit infrared radiation in all directions. Some of this re-emitted energy is lost to space, but much of it travels back downward. warming the lower atmosphere (specifically the troposphere).

Transportation Solutions are at Hand

*Automobiles are inefficient—only 14% of the fuel burned actually moves cars down the road *Alternative technologies, such as hybrid or all-electric vehicles, hydrogen fuel cells, and alternative fuels will help alleviate this problem *The increased availability of mass transit, such as buses, subways, and light rail all reduce the number of cars on the road and greenhouse gas emissions

Temperatures Continue to Rise

*Average surface temperatures (both land and ocean) have risen by about 1.1°C (2.0°F) in the past 100 years. *Most of this increase has occurred since the 1970s.

Responding to Climate Change

*Both adaptation and mitigation are needed to deal with climate change, because even if we halted all emissions now, pollution already in the atmosphere would continue driving global warming until equilibrium was reached -Adaptation is a more costly and less effective response to climate change than mitigation, however

Carbon-Neutrality

*Carbon offsets are one way for producers to achieve carbon-neutrality, a condition where no net carbon is emitted -The state in which an individual, business, or institution emits no net carbon to the atmosphere. This may be achieved by reducing carbon emissions and/or employing carbon offsets to offset emissions

National Security

*Climate change can contribute to humanitarian, geopolitical, and national security problems. *Economies and infrastructure may be weakened. *Oil and gas flows can be disrupted. *People in some affected regions may become refugees or turn to terrorism. -"Climate change will affect the Department of Defense's ability to defend the Nation and poses immediate risks to U.S. national security". The report described how storms, rising seas, and other impacts are "threat-multipliers," making small problems larger.

Current and Future Trends and Impacts

*Climate change has already had numerous impacts on the physical properties of our planet, on organisms and ecosystems, and on human well-being. *It also predicts future changes in these phenomena as well as impacts on wildlife, ecosystems, and society.

Proxy Indicators Tell Us About the Past

*Climate scientists drill into ice caps, ice sheets, and glaciers to analyze the tiny bubbles of atmosphere that collected as the ice formed. -By studying the chemistry of the bubbles in each layer in these ice cores, scientists can determine atmospheric composition, greenhouse gas concentrations, temperature, snowfall, solar activity, and even (from trapped soot particles) the frequency of forest fires and volcanic eruptions during each time period *Glaciers in Antarctica have provided information dating back 800,000 years. *Other proxy measurements include sediment cores drilled below bodies of water, tree rings, packrat middens in arid regions, and the isotope concentration of samples from coral reefs. -Sediments often preserve pollen grains and other remnants from plants that grew in the past -Tree rings are also used to study fire history, because a charred ring indicates that a fire took place at the site in that year. -Packrats are rodents that carry seeds and plant parts back to their middens, or dens, in caves and rock crevices sheltered from rain. -Living corals take in trace elements and isotope ratios from ocean water as they grow, and they incorporate these chemical clues, layer by layer, into growth bands in the reefs they build.

Miami, Florida, is One of Many U.S. Cities Vulnerable to Sea Level Rise

*Currently more than half of the U.S. population lives in coastal counties, and 3.7 million Americans live within 1 vertical meter of the high tide line. *South Florida is judged to be the most at-risk, with 2.8 million people and 1.8 million acres vulnerable.

Global Climate Change (Climate Change)

*Describes changes in temperature, precipitation, and the frequency and intensity of storms across the world. -Systematic change in aspects of Earth's climate, such as temperature, precipitation, and storm intensity. Generally refers today to the current warming trend in global temperatures and the many associated climatic changes.

Economics

*Economically, climate change is expected to widen the gap between the rich and poor, as people with less wealth rely more heavily on resources likely to be disrupted (such as local food and water). *The social cost of carbon is estimated to be somewhere between $10-350 per ton. *The Stern Review on the Economics of Climate Change concluded that climate change could cost the world 5-20% of GDP by the year 2200. *Investing just 1% of GDP starting now could help to avoid many of these costs.

We are Developing Solutions in Electricity Generation

*Electricity generation produces the largest portion (40%) of U.S. carbon dioxide emissions *Energy conservation technologies, such as new generations of light bulbs, appliances, and building materials, can reduce energy use and emissions by 30% or more *Switching from higher-pollution sources of energy, such as coal, to cleaner ones, such as natural gas, nuclear, and renewables also reduces emissions

Energy Returned on Investment (EROI)

*Energy sources are assessed using EROI, which is calculated by: *EROI = Energy returned / Energy invested *Ratios rise when extraction becomes easier or more efficient, and lower when resources become depleted and harder to extract *EROI ratios for conventional oil and natural gas in the U.S. declined from 24:1 in the 1950s to 11:1 in recent years -The ratio determined by dividing the quantity of energy returned from a process by the quantity of energy invested in the process. Higher EROI ratios mean that more energy is produced from each unit of energy invested

Where Will We Turn For Energy?

*Enormous amounts of energy, money, and technology are now being used to extend our reach for fossil fuels *Oil and gas wells are being drilled deeper, and into places that were once unreachable (Arctic sea beds, farther offshore in the ocean, etc) *New resources, such as oil sands, are also being tapped -There is, however, a different way we can respond to the ongoing depletion of conventional fossil fuel resources: We can hasten the development of clean and renewable energy sources to replace them

Carbon Footprint

*Expresses the amount of carbon we are responsible for emitting -The cumulative amount of carbon, or carbon dioxide, that a person or institution emits, and is indirectly responsible for emitting, into the atmosphere, contributing to global climate change

Fossil Fuels: Their Formation, Extraction, and Use

*Fossil fuels were formed hundreds of millions of years ago, from organisms performing photosynthesis *After death, these organisms ended up in an anaerobic (one that has little or no oxygen) environment, where their organic matter was converted by heat and pressure into a fossil fuel -Organic matter that accumulates at the bottoms of such water bodies may be converted into crude oil, natural gas, or coal, depending on (1) the chemical composition of the material, (2) the temperatures and pressures to which it is subjected, (3) the presence or absence of anaerobic decomposers, and (4) the passage of time

Surface Temperatures are Projected to Rise for the Years 2081-2100, Relative to 1986-2005.

*Future changes in temperature are predicted to vary from region to region. *Polar regions, for example, are expected to experience the most severe warming.

It Takes Energy to Make Energy

*Harvesting energy requires the use of heavy machinery, construction of roads, pipeline, waste ponds, storage tanks, and more — all requiring investments of energy

Central Case Study:Alberta's Oil Sands and the Keystone XL Pipeline

*Huge areas of tar sands are available around Alberta, Canada, and the impacts of extracting and processing the oil are huge *To extract oil from oil sands, companies must: *Clear the forest and strip-mine the land. *Mix the deposits with hot water and chemicals to separate the bitumen from sand *Store wastewater in toxic tailings lakes *Until oil prices began rising in 2003, extracting and processing oil from these deposits was not profitable *One of the biggest buyers of tar sands oil is the United States *To facilitate the transport of tar sands oil to the U.S., TransCanada constructed a large pipeline called the Keystone XL pipeline. *An extension of this pipeline has been proposed to be built through the Dakotas to shorten the distance, increase capacity, and reach productive oil fields in North Dakota and Montana (slide 7) *Protests quickly began when this extension was proposed, with objections including: *Oil use should be reduced, and we should be transitioning to renewable energy instead *Oil spills could contaminate the Sandhills area of Nebraska and the Ogallala Aquifer *In 2015, President Obama decided against approving the pipeline

Sources of Energy

*Humanity has devised many ways to harness the renewable and nonrenewable forms of energy available on our planet (slide 8)

Direct Measurements Tell Us About the Present

*In 1958, Charles Keeling began analyzing hourly air samples from a monitoring station at Hawaii's Mauna Loa Observatory -Direct long-term measurements began in 1958, when Charles Keeling started collecting these data at Hawaii's Mauna Loa Observatory. *CO2 concentrations have increased from 315 ppm in 1958 to over 400 ppm today.

United Nations Framework Convention on Climate Change (FCCC)

*In 1992, many nations signed this, which used a voluntary approach to reduce greenhouse gas emissions *This failed, and emissions kept rising -An international treaty signed in 1992 outlining a plan to reduce emissions of greenhouse gases. Gave rise to the Kyoto Protocol. This treaty outlined a plan for reducing greenhouse gases emissions to 1990 levels by the year 2000 through voluntary approach

Kyoto Protocol

*In 1997, it mandated signatory nations, by the period 2008-2012, to reduce emissions of six greenhouse gases to levels below those of 1990. *The United States was the only nation not to ratify it *Factoring out economic slowdowns, a 1.9% increase in emissions occurred in these nations as of 2012 *Nations that signed the Kyoto Protocol had decreased their emissions by 10.6% from 1990 levels. However, much of this reduction was due to economic contraction in Russia and nations of the former Soviet Bloc following the breakup of the Soviet Union. -An international agreement drafted in 1997 that called for reducing, by 2012, emissions of six greenhouse gases to levels lower than their levels in 1990. It has been extended to 2020 until a replacement treaty can be reached. An outgrowth of the United Nations Framework Convention on Climate Change.

Cap-and-Trade Bill

*In 2009, the U.S. House of Representatives passed the bill that would have created a system where industries and utilities compete to reduce emissions for financial gain *This bill did not pass the Senate, so the EPA began issuing tighter restrictions on power plants, and President Obama issued a Climate Action Plan to address climate change -An emissions trading system in which the government determines an acceptable level of pollution and then issues polluting parties permits to pollute. A company receives credit for amounts it does not emit and can then sell this credit to other companies.

Impacts Vary by Region

*In the Arctic, ice sheets are melting, sea ice is thinning, storms are increasing, and native people and animals are having more difficulty hunting *The 2014 National Climate Assessment predicted many future impacts of climate change on the United States (slide 56) *Temperatures in the United States are predicted to rise by another 1.7-5.6°C (3-10°F) by the end of this century, depending on how quickly emissions are reduced

Climate Change Contributes to the Power and Reach of Devastating Storms like Superstorm Sandy.

*In the United States, Superstorm Sandy demonstrated the potential havoc that storm surges can cause. *The storm caused $65 billion in damage, killed 160, and left thousands homeless. *Superstorm Sandy was not caused by global warming, but it was facilitated and strengthened by it, due to the increase in ocean temperatures -Superstorm Sandy was not directly and solely caused by global warming, but in a statistical sense it was facilitated and strengthened by it. Warmer ocean water boosts the chances of large and powerful hurricanes. A warmer atmosphere retains more moisture that a hurricane can dump onto land. A blocking pattern in the jet stream contributed to Sandy's energy. And higher sea levels magnify the damage caused by storm surges.

Temperatures Have Risen Across the United States.

*In the United States, temperatures in most areas have risen by more than 1 full degree Fahrenheit in just the past two decades. *This trend will continue because we are still emitting greenhouse gases, and the ones already in the atmosphere will continue warming the globe for decades to come.

Greenhouse Gases

*Include water vapor (H2O), ozone (O3), carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4), and halocarbons -Gases that absorb infrared radiation released by Earth's surface and then warms the surface and troposphere by emitting energy, thus giving rise to the greenhouse effect.

Forestry

*Increased CO2 may spur higher timber growth, but warming temperatures also increase the rates of invasive species, fires, and disease outbreaks -Milder winters and hotter, drier summers are promoting outbreaks of bark beetles that are destroying millions of acres of trees

You Can Address Climate Change

*Individual decisions that reduce carbon footprints will play a major role in addressing climate change *Choosing energy-efficient appliances *Eating less meat. *Living near your work to reduce commuting times

Climate

*It influences virtually everything around us, and climate change looks to be the phenomenon that most shapes the near future for young people *Climate describes an area's long-term atmospheric conditions: Temperature, Precipitation, Wind, Humidity, Barometric Pressure, and Solar Radiation -The pattern of atmospheric conditions that typifies a geographic region over long periods of time (typically years, decades, centuries, or millennia). *The Earth's climate varies naturally, but disruptive changes are unfolding rapidly, with human activities accelerating them.

Intergovernmental Panel on Climate Change

*It was established in 1988 by the United Nations to review and summarize all available data in climate studies for policymakers and general public *In 2013 and 2014, the IPCC released its Fifth Assessment Report, summarizing trends in surface temperature, precipitation patterns, snow and ice cover, sea levels, storm intensity, and other factors. -An international panel of climate scientist and government officials established in1988 by the United Nations Environment Programme and the World Meteorological Organization. Its mission is to assess and synthesize scientific research on global climate change to offer guidance to the world's policymakers, primarily through periodic published reports.

Climate Change Affects Organisms and Ecosystems

*Many biological phenomena that rely on temperature have been modified due to global warming. *In the spring, plants are leafing, insects are hatching ,birds are migrating, and animals are breeding earlier. *Many animals are expanding their ranges toward cooler areas (higher in elevation or latitude).

What Role should Government Play?

*Many people disagree on what role the government should play. *Should it mandate change through laws and regulations? *Should no policies be implemented and private enterprise be allowed to develop its own solutions? *In 2007, the U.S. Supreme Court ruled that carbon dioxide was a pollutant that the EPA could regulate under the Clean Air Act

Melting Ice has Far-Reaching Effects

*Many tropical mountaintop glaciers have disappeared, and the few that remain are shrinking. *One out of six people worldwide live in regions that depend on mountain meltwater as a source of fresh water. *Polar ice is also melting very quickly, with the entire West Antarctic ice shelf potentially on its way to an unstoppable collapse *This would create a 3 m (10-ft) rise in sea levels. *As snow and ice melt, less reflective surfaces (bare ground or surface water) is exposed. This reduces the Earth's albedo, or capacity to reflect light, creating a positive feedback loop -As snow and ice melt, darker, less reflective surfaces (such as bare ground and pools of meltwater) are exposed, and Earth's albedo, or capacity to reflect light, decreases. As a result, more of the sun's rays are absorbed at the surface, and the surface warms. In a process of positive feedback, this warming causes more ice and snow to melt, which in turn causes more absorption of radiation and more warming *The loss of Arctic sea ice has led to the opening of new shipping lanes, and many countries jockeying for position to claim regions of the Arctic for oil and mineral extraction *Arctic warming is also thawing permafrost (permanently frozen ground), causing the release of underground methane, which further intensifies warming

States and Cities are Advancing Climate Change Policy

*Mayors from more than 1,000 cities have signed on to the U.S. Mayors Climate Protection Agreement, committing to policies that "meet or beat" Kyoto Protocol guidelines *The most aggressive is California, which has a goal to cut greenhouse gas emissions 25% by 2020, and has established a cap-and-trade program *States in the Regional Greenhouse Gas Initiative, including Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New York, Rhode Island, and Vermont run a joint cap-and-trade program -From 2005 to 2013, these states cut their CO2 emissions from power plants by 40%, even as their economies grew. It is estimated that investment of the auction proceeds will save nearly $3 billion in energy costs and eliminate 10 million tons of CO2 emissions

Aerosols

*Microscopic droplets that can either have a warming or cooling effect when present in the atmosphere *Soot Particles ("Black Carbon Aerosols") cause warming by absorbing solar energy *Most other aerosols (such as Sulfur) reflect solar energy and have a cooling effect -They can be released by major volcanic eruptions, causing Earth's climate to cool for up to several years. This occurred in 1991 with the eruption of Mount Pinatubo in the Philippines.

Mitigation

*Mitigation aims to alleviate or reduce the severity of climate change by: *Improving energy efficiency *Switching to clean and renewable energy sources *Preserving forests *Recovering landfill gases *Protecting soil quality -The pursuit of strategies to lessen the severity of climate change, notably by reducing emissions of greenhouse gases -The sooner we begin reducing emissions, the lower the level at which they will peak, and the less we will alter climate

Agriculture

*Moderate warming may increase agricultural output in some temperate areas because growing seasons become longer, but increased droughts will diminish yields in for many. -The IPCC predicts that global crop yields will increase somewhat initially—but beyond a rise of 3°C (5.4°F), the IPCC expects crop yields to decline. This would worsen hunger in many of the world's developing nations.

Nature offers us a variety of energy sources

*Most of the Earth's energy comes from the sun, which drives wind, the water cycle, and photosynthesis *When plants and other organisms die and are buried in sediments under particular conditions, their stored chemical energy may eventually be incorporated into fossil fuels, such as oil, coal, and natural gas *Other forms of energy in the earth include geothermal energy from the core and from the bonds between protons and neutrons in atoms *Energy sources like sunlight, geothermal energy, and tidal energy are perpetually renewable *Coal, oil, and natural gas are considered nonrenewable because it takes thousands of years for the biosphere to generate the organic matter consumed by our society in a single day of fossil fuel combustion

Net Energy

*Net energy expresses the difference between energy returned and energy invested *Net energy = Energy returned - energy invested -The quantitative difference between energy returned from a process and energy invested in the process. Positive net energy values mean that a process produces more energy than is invested

Oil and Natural Gas

*Oil and natural gas are derived from marine plankton that died, sank to the sea bottom, became buried, and transformed by time, heat, and pressure *These eventually settle under impermeable rock formations, which must be drilled through before the oil and gas can be accessed

Oil Sands

*Oil sands are a mixture of moist sand and clay containing 1-20% bitumen, a thick and heavy form of petroleum that is rich in carbon and poor in hydrogen *Oil sands result from crude oil deposits that have been degraded and chemically altered by water erosion and bacterial decomposition -Oil from oil sands is extracted by two main methods: strip mining and steam extraction -Bitumen from either process must then be chemically refined and processed to create synthetic crude oil (called syncrude)

Milankovitch Cycle

*Over thousands of years, the Earth wobbles on its axis, varies in its tilt, and experiences changes in the shape of its orbit in regular long-term cycles -An axial wobble that occurs on a 19,000- to 23,000-year cycle; a 3-degree shift in the tilt of Earth's axis occurs on a 41,000-year cycle; and (c) a variation in Earth's orbit from almost circular to more elliptical, repeats every 100,000 years -Results in slight changes in the relative amount of solar radiation reaching Earth's surface at different latitudes. As the cycles proceed, they change the way solar radiation is distributed over Earth's surface and contribute in atmospheric heating and circulation that have triggered glaciations and other climate changes. https://www.youtube.com/watch?v=6lbJrvtxWNE

Climate Models

*Programs that combine what is known about atmospheric circulation, ocean circulation, atmosphere-ocean interactions, and feedback cycles to stimulate climate dynamics *The efficiency of the model is tested by entering past climate data and running the model toward the present. *Current models are imperfect because the Earth's climate system is complex, and many feedback systems are not known -A computer program that combines what is known about weather patterns, atmospheric circulation, atmosphere- ocean interactions, and feedback mechanisms, to stimulate climate processes -This requires manipulating vast amounts of data with complex mathematical equations—a task not possible until the advent of modern computers.

Adaptation

*Pursues strategies to cushion ourselves from the impacts of climate change *The pump systems installed at Miami Beach is an example of an adaptation strategy -The pursuit of strategies to protect ourselves from the impacts of climate change -Other examples of adaptation include restricting coastal development; adjusting farming practices to cope with drought; and modifying water management practices to deal with reduced river flows, glacial outburst floods, or salt contamination of groundwater

Greenhouse Effect

*Re-warming of the lower atmosphere by emitting of infrared energy by greenhouse gases -The warming of Earth's surface and atmosphere (especially in the troposphere) caused by the energy emitting by greenhouse gases

Global Warming

*Refers specifically to an increase in Earth's average temperature, and is only one aspect of climate change -An increase in Earth's average surface temperature. The term is most frequently used in reference to the pronounce warming trend of recent decades. It is one aspect of global climate change and in turn drives other components of climate change.

Carbon Capture and Storage

*Refers to technologies or approaches that remove carbon dioxide from emissions and then store it below ground under pressure in deep salt mines, depleted oil and gas deposits, or other underground reservoirs *These technologies and spaces are not yet adequate for sequestering enough carbon to impact global atmospheric levels -Technologies or approaches to remove Carbon Dioxide from emissions of power plants or other facilities, and sequester, or store, it (generally in liquid form) underground under pressure in locations where it will not seep out, in an effort to mitigate global climate change

Are We Responsible for Climate Change?

*Scientists agree that today's global warming is a result of the increase in greenhouse gas concentrations in our atmosphere due to: *Combustion of fossil fuels for energy *Loss of carbon-absorbing vegetation due to deforestation and other changes in land use *Public debates over climate change are primarily the result of corporate interests, political think tanks, and a handful of scientists funded by fossil fuel industries

Oil Shale

*Sedimentary rock filled with organic matter that can be processed into shale oil *Oil shale is formed by the same processes that form crude oil but occurs when the organic matter was not buried deeply enough or subjected to enough heat and pressure to form oil -Sedimentary rock filled with kerogen that can be processed to produce liquid petroleum. Oil shale is formed by the same processes that form crude oil but occurs when kerogen was not buried deeply enough or subjected to enough heat and pressure to form oil -One way to process oil shale is to bake it in the presence of hydrogen and in the absence of air to extract liquid petroleum (a process called pyrolysis)

Will Emissions Cuts Harm the U.S. Economy?

*Since the U.S. has high resource use and per capita emissions, policymakers often assume that restrictions on emissions will harm the economy -Yet nations such as Germany, France, and the United Kingdom have reduced their emissions since 1990 while enhancing their economies and providing their citizens high standards of living *Renewable energy has actually been an economic boom for countries like China and Germany -Industrialized nations are also the ones most likely to gain economically from major energy transitions, because they are best positioned to invent, develop, and market new technologies to power the world in a post-fossil-fuel era

We Rely Mostly On Fossil Fuels

*Since the industrial revolution, fossil fuels have replaced biomass as our dominant source of energy *The high energy content makes these more efficient to burn, ship, and store -A single gallon of oil contains as much energy as a person would expend in nearly 600 hours of human labor *We use fossil fuels for transportation, manufacturing, heating, cooking, and to generate electricity

Rising Sea Levels Threaten the Maldives.

*Small island countries like the Maldives, most of which are less than 1 m above sea level, may become climate refugees as sea level rises *In 2009, the Maldives held an "underwater cabinet meeting" to bring attention to the plight of their country -This nation's capital (a) is crowded onto an island averaging just 1.5 m (5 ft) above sea level. In 2009, the Maldives' president led his cabinet in an underwater meeting (b) to focus international attention on the plight of island nations vulnerable to sea-level rise.

Carbon Pricing

*Strategies are designed to compensate the public for the external costs we all suffer from climate change resulting from greenhouse gas emissions *It removes the burden of paying for these impacts from the public and shifts it to the entities responsible for emissions *In theory, if producers are charged a price for emissions, they will have a strong economic incentive to devise ways to reduce emissions -The practice of putting a price on the emission of carbon dioxide, either through carbon trading or a carbon tax, as a means to address global climate change. Carbon pricing compensates the public for the external costs of fossil fuel use by shifting costs to emitters, and creates financial incentives to reduce emissions

Three Factors Influence Climate

*The Sun provides light and warmth. The Atmosphere prevents major temperature shifts from night to day. The Oceans store and transport heat and moisture. -Without the sun, Earth would be dark and frozen. Without the protective layer of gases (atmosphere), Earth would be as much as 33°C (59°F) colder on average, and temperature differences between night and day would be far greater than they are. The Oceans store and transport heat and moisture. *The sun supplies most of our planet's energy, which the atmosphere absorbs or reflects most of it before it even reaches the surface. -Earth's atmosphere, clouds, land, ice, and water together absorb about 70% of incoming solar radiation and reflect the remaining 30% back into space.

Ocean Circulation

*The Thermohaline circulation of the ocean moves warm, tropical water north, where the heat is released near Western Europe -Because cooler water is denser than warmer water, the cooler water at the poles tends to sink, and the warmer surface water from the equator moves to take its place. *Freshwater input from Greenland's, melting ice sheets may disrupt this flow -Such an occurrence would plunge Europe into much colder conditions *Multiyear climate variability also arises from the el Niño-Southern Oscillation *Systematic shifts in atmospheric pressure, sea surface temperature, and ocean circulation in the tropical Pacific Ocean

Radiative Forcing

*The amount of change in thermal energy that a given factor exerts on the Earth's temperature *Positive forcing warms the surface; Negative forcing cools it. *When all factors are considered, the Earth is experiencing net radiative forcing of 2.3 watts/m2 expresses change in energy input -It quantifies the influence that aerosols, greenhouse gases, and other factors exert over Earth's energy balance. -The amount of change in thermal energy that a factor causes in influencing Earth's temperature

Paleoclimate

*The climate in the ancient past, is vital for providing a baseline against which we can measure changes to the climate today

Energy is Unevenly Distributed

*The distribution of fossil fuel reserves varies from region to region (slide 12) *In general, developed countries consume more fossil fuel than developing countries *Developing countries tend to use energy for subsistence activities (such as growing and preparing food and heating homes) , while developed countries use it for transportation, industry, and other uses *In the United States, coal, oil, and natural gas supply 82% of the total energy demand

Extreme Weather is Becoming "The New Normal"

*The frequency of extreme weather events (droughts, floods, hurricanes, tornadoes, etc.) has doubled in the United States since 1970. *Insurers have recorded a 50% increase in losses from extreme weather in South America, a doubling of losses in Europe, and even higher rates across the rest of the world.

Greenhouse Gas Concentrations are Rising Fast

*The greenhouse effect has been present throughout Earth's history, and has kept the planet warm enough to support life. -Without the natural greenhouse effect, our planet would be too cold to support life as we know it. Thus, it is not the natural greenhouse effect that concerns scientists today but rather the anthropogenic (human-generated) intensification of the greenhouse effect. *Over the past 250 years, humans have caused a net accumulation of greenhouse gases in the atmosphere, primarily due to the release of carbon in fossil fuels during combustion. *Combustion of fossil fuels transfers carbon from one reservoir (underground deposits) to another (the atmosphere). *Forests serve as a reservoir for carbon as plants conduct photosynthesis and store carbon in their tissues. When we clear forests, we reduce the biosphere's ability to remove carbon dioxide from the atmosphere. *Nitrous oxide in the atmosphere has increased, primarily due to auto emissions, feedlots, and the use of synthetic nitrogen fertilizers. *Ozone concentration in the troposphere has also grown, the result of photochemical smog -Since the start of the industrial revolution around 1750, global concentrations of carbon dioxide, methane, and nitrous oxide in the atmosphere have increased markedly.

Ocean Absorption

*The oceans hold 50 times more carbon than the atmosphere, but are absorbing less CO2 than we are adding to the atmosphere. *As ocean water warms, it absorbs less CO2 because gases are less soluble in warmer water—a positive feedback effect that accelerates warming of the atmosphere.

Global Warming Potential

*The relative ability of a greenhouse gas molecule to contribute to warming. Values are expressed in relation to carbon dioxide, which is assigned a value of 1. -Example: At a 20 year time horizon, a molecule of methane is 84 times more potent than a molecule of carbon dioxide. Yet because a typical methane molecule resides in the atmosphere for less time than a typical carbon dioxide molecule, methane's global warming potential is reduced at a longer time horizons (it is 28 at 100-year horizon).

Solar Output

*The sun varies in the amount of radiation it emits. *Scientists believe this has not had a significant effect on the Earth's average surface temperature, assigning it a value of only 0.05 watts/m2 of radiative forcing.

Revenue-Neutral Carbon Tax

*There is no net transfer of revenue from taxpayers to the government -A type of fee and dividend program in which funds from the carbon tax that a government collects are disbursed to citizens in the form of payments or tax refunds. It is "revenue-neutral" because the government neither gains nor loses revenue in the end

We will Need Multiple Strategies

*There is not a single "magic bullet" for mitigating climate change; rather, environmental scientists advocate breaking the problem up into smaller, more manageable strategies (slide 70) -Pacala and Socolow have identified 15 strategies that could each eliminate 1 billion tons of carbon per year by 2050 if deployed at a large scale

Proxy Indicators

*Types of indirect measurements that serve as substitutes for direct measurements -A source of indirect evidence that serves as a proxy, or substitute, for direct measurement and that sheds light on past climate. -Examples: Data from ice cores, sediment cores, tree rings, packrat middens, and coral reefs

Crude Oil

*Unrefined oil extracted from the ground. -Oil in its natural state, as it occurs once extracted from the ground but before processing and refining

Petroleum

*Usually refers to oil, but may also refer to oil and natural gas collectively -Oil is also know as this, but the term is also used to refer to both oil and natural gas together

Carbon Offsets

*Voluntary payments paid by a producer that is unable to reduce its emissions, and given to another institution that can *For example, a coal-burning power plant could pay for a reforestation project to plant trees that will soak up as much carbon dioxide as the coal plant emits -A voluntary payment to another entity intended to enable that entity to reduce the greenhouse gas emissions that one is unable or unwilling to reduce oneself. The payment thus offsets one's own emission -Example: A university could fund the development of clean and renewable energy projects to make up for fossil fuel energy the university uses.

Fossil Fuels

*When plants and other organisms die and are buried in sediments under particular conditions, their stored chemical energy may eventually be incorporated into this -A nonrenewable natural resource, such as crude oil, natural gas, or coal, produced by the decomposition and compression of organic matter from ancient life. They have provided most of society's energy since the industrial revolution -We rely on three main fossil fuels, in the form of a solid (coal), liquid (oil), and gas (natural gas)

Global Average Sea Level has Risen More than 24 cm (9.5 in.) Since 1880.

*Worldwide, average sea levels have risen 24.1 cm (9.5 in.) in the past 135 years. *This leads to more beach erosion, coastal flooding, saltwater intrusion, and a greater impact by localized rises in sea level called storm surges.

Oil

-A fossil fuel produced by the slow underground conversion of organic compounds by heat and pressure. Oil is a mixture of hundreds of different types of hydrocarbon molecules characterized by carbon chains of different lengths -Thick blackish liquid

Shale Oil

-A liquid form of petroleum extracted from deposits of oil shale

Electricity

-A secondary form of energy that can be transferred over long distances and applied for a variety of uses -Coal is used mostly to generate electricity

Storm Surge

-A temporary and localized rise in sea level generated by a storm. -Higher sea levels lead to beach erosion, coastal flooding, intrusion of saltwater into aquifers, and greater impacts -The higher the sea level is to begin with, the farther inland a storm surge can reach.

Social Cost of Carbon

-An estimate of the total economic cost of damages resulting from the emission of carbon dioxide (from fossil fuel burning, deforestation, etc.) and resulting global climate change, in a per-ton basis. Estimate very widely, but the U.S. government currently uses an estimate of roughly $40/ton CO2

Consequences of Climate Change

-Impacts on agriculture, forestry, health, economics, and national security

Ocean Acidification

-The process by which today's oceans are becoming more acidic (attaining lower pH) as a result of increased carbon dioxide concentrations in the atmosphere. It occurs as ocean water absorbs carbon dioxide from the air and forms carbonic acid.

The Science Behind the Story: How Do Climate Models Work?

18.3