Global Climate Change Chapter 14

Topics Include: Earth’s climate system Human influences on climate Methods of climate research Impacts of global climate change Future trends and impacts Responding to climate change

Central Case Study: Rising Seas May Flood the Maldives Tourists think the Maldives Islands are a paradise Rising seas due to global climate change could submerge them Flood areas, erode beaches Damage coral reefs Residents have evacuated the lowest-lying islands Small nations do not cause of climate change Yet they suffer

What is climate change? Section 1

What is climate change? Climate change is the fastest-developing area of environmental science Climate: an area’s long-term atmospheric conditions Temperature, precipitation, wind, humidity, etc. Weather: short-term conditions at localized sites Global climate change: describes modifications in Earth’s climate Temperature, precipitation, storm frequency Global warming and climate change are not the same

Global warming Global warming: an increase in Earth’s average temperature Only one aspect of climate change Earth’s climate has varied naturally through time Today’s climate change is happening at an extremely rapid rate These changes are due to human fossil fuel combustion and deforestation Understanding climate change requires understanding how our planet’s climate works

Three factors influence Earth’s climate The sun: without it, Earth would be dark and frozen It supplies most of Earth’s energy The atmosphere: without it, Earth’s temperature would be much colder Clouds, land, ice, and water absorb 70% of incoming solar radiation The remaining 30% is reflected back into space The oceans: shape climate by storing and transporting heat and moisture

The fate of solar radiation

Greenhouse gases warm the lower atmosphere As Earth’s surface absorbs solar radiation, the surface temperature increases and emits infrared radiation Greenhouse gases: atmospheric gases that absorb infrared radiation Water vapor, ozone, carbon dioxide, nitrous oxide, methane, halocarbons (chlorofluorocarbons [CFCs]) Greenhouse gases re-emit infrared energy Some energy is lost to space Greenhouse effect: the energy that travels downward warms the atmosphere and the planet’s surface

Greenhouse gases are not all equal Greenhouse gases differ in their ability to warm the trophosphere and surface Global warming potential: the relative ability of one molecule of a greenhouse gas to contribute to warming Expressed in relation to carbon dioxide (potential = 1) Nitrous oxide is 298 times as potent as carbon dioxide Carbon dioxide contributes most to the greenhouse effect It is less potent, but far more abundant, than other gases The major type of human-caused emissions

Greenhouse gas concentrations are rising The greenhouse effect is natural Greenhouse gases have always been in the atmosphere We are concerned with the anthropogenic (human-caused) intensification of the greenhouse effect We have increased the concentration of these gases beyond what we have ever experienced CO2 has increased from 280 ppm (1700s) to 400ppm ( and over!) The highest in 800,000 (possibly 20 million) years

U.S. emissions of major greenhouse gases

Why have CO2 levels risen so rapidly? Burning fossil fuels transfers CO2 from underground deposits into the atmosphere The main reason CO2 levels have increased Deforestation contributes to rising atmospheric CO2 Plants store carbon in their tissues Less CO2 is absorbed from the atmosphere

Other greenhouse gases are increasing Methane: fossil fuels, livestock, landfills, crops (rice) Levels have increased 2.5 times since 1750 Nitrous oxide: feedlots, chemical manufacturing plants, auto emissions, and synthetic nitrogen fertilizers Risen 18% since 1750 Ozone levels have risen 36% due to photochemical smog The Montreal Protocol has reduced halocarbons (CFCs) Water vapor: the most abundant greenhouse gas Contributes most to the natural greenhouse effect But concentrations have not changed

Natural factors affecting climate Section 2

Most aerosols exert a cooling effect Aerosols: microscopic droplets and particles They have either a warming or a cooling effect Soot (black carbon aerosols) causes warming by absorbing solar energy But most tropospheric aerosols cool the atmosphere by reflecting the sun’s rays Sulfate aerosols from fossil fuel combustion may slow global warming, at least in the short term Volcanic eruptions reduce sunlight reaching Earth’s surface and cool the Earth

Radiative forcing shows changes in energy Radiative forcing: the amount of change in thermal energy that a given factor causes Positive forcing warms the surface Negative forcing cools it Earth is experiencing radiative forcing of 1.6 watts/m2 more than it is emitting to space—enough to alter the climate

Milankovitch cycles also influence climate Milankovitch cycles: periodic changes in Earth’s rotation and orbit around the sun Alter the way solar radiation is distributed over Earth These cycles modify patterns of atmospheric heating Triggering climate variation Glaciation: cold temperatures and ice sheets

Solar output and oceans influence climate Solar output: the sun varies in the radiation it emits Variation in solar energy (e.g., solar flares) has not been great enough to change Earth’s temperature Radiative forcing is 0.12 watts/m2 —less than any human causes Ocean absorption: oceans hold 50 times more carbon than the atmosphere Slows global warming but does not prevent it As oceans warm, they absorb less CO2, accelerating warming

Ocean circulation influences climate Ocean circulation: ocean water exchanges heat with the atmosphere Currents move energy from place to place The ocean’s thermohaline circulation system affects regional climates Moving warm tropical water north, etc. Greenland’s melting ice sheet will affect this flow El Niño and La Niña events change regional weather Dry areas get wetter, while wet areas get dryer

How did we figure this all out? Section 3

Proxy indicators tell us about the past Proxy indicators: indirect evidence that serve as substitutes for direct measurements of past climate Ice caps, ice sheets, and glaciers hold clues to Earth’s climate history Trapped bubbles in ice cores provide a timescale of: Atmospheric composition, greenhouse gas concentrations, temperature, snowfall, solar activity Frequency of fires and volcanic eruptions Other indicators include pollen preserved in sediment, tree rings, coral reefs

800,000 years of history in an ice core (Vostok Ice Core-National Ice Core) Concentrations of gas are correlated with temperature Trapped bubbles contain samples of ancient air

Ice Core shows volcanic ash National Ice Core Laboratory Longest core to date is over 3,400meters and dates back 68,000years from the West Antarctic Divide Ice Sheet! Core Freezer! Ice Core shows volcanic ash

Direct measurements tell us about the present We document daily fluctuations in weather Temperature, rainfall, wind speed, air pressure Measuring ocean and atmospheric chemistry began in 1958 Hourly air samples from Mauna Loa Observatory in Hawaii show that… Atmospheric CO2 concentrations have increased from 315 ppm to 400 ppm since 1958

Models help us predict the future Climate models: combine data from atmospheric and ocean circulation and interactions To simulate climate processes If a model accurately reconstructs current climate It may accurately predict future climate Modeling is hard because climate and feedback loops are so complex

Current and future trends and impacts Evidence that climate has changed is everywhere Fishermen in the Maldives, ranchers in Texas, homeowners in Florida, etc. We cannot blame any single weather event on climate change But extreme weather is part of a pattern backed by an immense volume of scientific data The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 Composed of hundreds of international scientists and government representatives

The IPCC’s Fourth Assessment Report (2007) The IPCC report summarized thousands of studies It documented observed trends in: Surface temperature, precipitation patterns, snow and ice cover, sea levels, storm intensity, etc. It predicted future changes on wildlife, ecosystems, and human societies It discussed strategies to pursue in response to climate change The authors assigned statistical probabilities to its conclusions and released conservative estimates We just had the Fifth Assessment Report meeting in April

The IPCC’s Fourth Assessment Report (2007)

What will the future bring? Section 5

Temperatures continue to increase Average surface temperatures increased 0.74 °C since 1906 Most of the increase occurred in the last few decades The 17 warmest years on record have been since 1990 Since the 1960s, each decade has been warmer than the last

The future will be even hotter In the next 20 years, temperatures will rise 0.4C At the end of the 21st century, temperatures will be 1.8 to 4.0C higher than today’s We will have unusually hot days and heat waves Polar areas will have the most intense warming Sea surface temperatures will rise Hurricanes and tropical storms will increase in power and duration

Temperatures will rise globally Projected increases in surface temperature for 2090–2099 relative to 1980–1999

Precipitation is changing, too Some regions are receiving more rain and snow Other areas are receiving less In the U.S. Southwest, droughts have become more frequent and severe Harm agriculture, promote soil erosion, reduce water supplies, and trigger fires In dry, humid regions, heavy rains cause flooding Kill people, destroy homes, and inflict billions of dollars in damage Example: 2008 floods in Iowa and the Midwest

Projected changes in precipitation Precipitation will increase at high latitudes and decrease at low and middle latitudes – worsening water shortages in poor nations

Melting of snow and ice has severe effects Mountaintop glaciers are disappearing Glaciers on tropical mountaintops have disappeared The remaining 26 of 150 glaciers in Glacier National Park will be gone by 2030 Reducing summertime water supplies to millions Melting of Greenland’s Arctic ice sheet is accelerating Warmer water is melting Antarctica’s coastal ice shelves Interior snow is increasing due to more precipitation Melting ice exposes darker, less-reflective (lower albedo) surfaces, which causes even more melting

Worldwide, glaciers are melting rapidly Nations are rushing to exploit underwater oil and mineral resources made available by newly opened shipping lanes Permafrost (permanently frozen ground) is thawing Destabilizing soil, buildings, etc., and releasing methane Montana’s Grinnell Glacier has retreated substantially since 1938

Rising sea levels will affect millions Runoff from melting glaciers and ice cause sea levels to rise As oceans warm, they expand Leading to beach erosion, coastal floods, intrusion of salt water into aquifers, and storm surges

Coastal areas will flood Storm surge: temporary, localized rise in sea level Caused by the high tides and winds of storms A 2004 earthquake caused a tsunami (tidal wave) that killed 100 Maldives residents Caused $470 million in damages Cities will be flooded 53% of people in the U.S. live in coastal areas Vulnerability to storm surges will increase Rising seas eliminate marsh grasses; dams stop sediment from replenishing deltas

Rising sea levels will devastate coasts Rising seas will displace millions of people from coastal areas Many will have to invest in costly efforts to protect against high tides and storm surges Areas that will be most affected include: Densely populated, poor regions (e.g., Bangladesh) Storm-prone regions (e.g., Florida) Coastal cities (e.g., Houston) Areas with land subsidence (e.g., U.S. Gulf Coast) Pacific Islands will have to be evacuated

Coral reefs are threatened Coral reefs are habitat for marine species, tourism destinations, and protect coastlines Warmer waters contribute to coral bleaching Which kills corals Ocean acidification: caused by increased CO2 Organisms can’t build their exoskeletons Oceans have already decreased by 0.1 pH unit They will decrease 0.15 to 0.35 more units—enough to kill most coral reefs, which will be catastrophic

Organisms and ecosystems are affected Organisms are adapted to their environments They are affected when those environments change Global warming modifies temperature-dependent phenomena (e.g., timing of migration, breeding) Species will move toward the poles or up in elevation 20–30% of species will be threatened with extinction Rare species will be pushed out of preserves More CO2 may increase plant growth, but… Droughts, fire, and disease will decrease plant growth Fewer plants means more CO2 in the atmosphere

Animals and plants have nowhere to go Animals and plants adapted to montane environments will be forced uphill until there is no place to go Many bird species have shifted their ranges northward in the past 40 years

Climate change affects society Societies are already feeling impacts of climate change Agriculture: shortened growing seasons, decreased production, crops more susceptible to droughts Increasing hunger in many developing nations Forestry: increased fires, invasive species Insect and disease outbreaks Health: heat waves and stress can cause death Respiratory ailments, expansion of tropical diseases Disease and sanitation problems from flooding Drowning from storms

Climate change affects economics Costs will outweigh benefits of climate change It will widen the gap between rich and poor Those with less wealth and technology will suffer most It will cost 1–5% GDP (Gross Domestic Product) on average globally Poor nations will lose more than rich ones The Stern Review on the Economics of Climate Change predicts it will cost 5–20% of GDP by 2200 Investing 1% of GDP now could avoid these costs

Impacts will vary regionally Where we live will determine how we experience the impacts of climate change Temperature changes have been greatest in the Arctic Melting ice sheets, thinning ice, increasing storms, etc. Harder for people and polar bears to hunt

The U.S. Global Change Research Program In their 2009 report, scientists reported and predicted: Temperature increases (2.2 – 6.1C higher) Worse droughts and flooding Decreased crop yields Water shortages Health problems and diseases Higher sea levels, beach erosion, destroyed wetlands Drought, fire, and pests will change forests More grasslands and deserts, fewer forests Undermined Alaskan buildings and roads

Predictions from two climate models Temperature increases will be much smaller if emissions are lowered

Causes and consequences of climate change

Are we responsible for climate change? Scientists agree that increased greenhouse gases are causing global warming Burning fossil fuels is increasing greenhouse gases Despite overwhelming evidence for climate change: Many in the U.S. deny what is happening People debate if it is real and if humans are to blame Think tanks and a few scientists question it The news media present both sides, despite the evidence of climate change There is a shift in this thinking recently, and the media is saying that climate change is caused by humans

Shall we pursue mitigation or adaptation? Most people accept that we are changing Earth They are searching for solutions Mitigation: pursue actions that reduce greenhouse gas emissions to lessen the severity of climate change Energy efficiency, renewable energy, protecting soil, preventing deforestation Adaptation: accept that climate change is happening Pursue strategies to minimize its impacts on us Seawalls, coping with drought and less water, etc. We need to pursue both

Solutions Section 6

Developing solutions Electrical generation: the largest source of U.S. CO2 70% of electricity is from fossil fuels, especially coal To reduce fossil fuel use: Conservation, efficiency, cleaner or renewable energy Cogeneration, more efficient appliances Carbon capture: removes CO2 from power plant emissions Carbon sequestration (storage): storing carbon underground (old oil deposits, salt mines, etc.) We can’t store enough CO2 to make a difference

Transportation 2nd largest source of U.S. greenhouse gases Cars are extremely inefficient Solutions: drive fuel-efficient, hybrid, or electric cars Drive less and use public transportation Live near your job, so you can bike or walk

We can reduce emissions in other ways Agriculture: sustainable land management lets soil store more carbon Reduce methane emissions from rice and cattle Grow renewable biofuels Forestry: reforest cleared land, preserve existing forests Sustainable forestry practices Waste management: treating wastewater Generating electricity by incinerating waste Recovering methane from landfills Individuals can recycle, compost, reduce, or reuse goods

We need to follow multiple strategies There is no magic bullet for mitigating climate change Reductions can be achieved with technology we can use right away Just 15 strategies can eliminate 15 billion tons of CO2 by 2050 7 of the 15 would stabilize CO2 emissions

What role should government play? To reduce emissions, should the government: Mandate change through laws and regulations? Impose no policies and hope for solutions? Give private entities incentives to reduce emissions? Many businesses and politicians have opposed all government action Fearing it will cost industry and consumers In 2007 the U.S. Supreme Court ruled that the EPA could regulate CO2 as a pollutant

Where are we now with legislation? The 2009 House of Representatives’ cap-and-trade system did not pass the Senate Industries would compete to reduce emissions for financial gain Responsibility for emissions now goes to the EPA It began developing regulations in 2011 Emission limits will be phased in over years, while increasing efficiency and renewable energy This will minimize economic impacts and political opposition After most recent report this past May, we will be seeing changes in legislation hopefully soon

The FCCC U.N. Framework Convention on Climate Change: a plan to voluntarily reduce greenhouse gas emissions To 1990 levels by 2000 This voluntary approach did not succeed Signatory nations created a binding international treaty requiring emission reductions The Kyoto Protocol (1997): signatory nations must reduce emissions of six greenhouse gases To levels below those of 1990 (by 2008–2012)

The Kyoto Protocol tried to limit emissions This treaty took effect in 2005 After Russia became the 127th nation to ratify it The United States will not ratify the Kyoto Protocol It requires industrialized nations to reduce emissions But it does not require industrializing nations (China and India) to reduce theirs Other countries resent the U.S. because it emits 20% of the world’s greenhouse gases but won’t take action This undermines the treaty’s effectiveness Signatory nations have increased emissions 7.9%

Climate negotiations have progressed The Kyoto Protocol ended in 2012 The 2009 Copenhagen conference ended in discord China wouldn’t allow international monitoring Obama would not promise more than Congress had agreed to Cancun’s 2010 meeting was more productive Developed nations will help developing nations with technology and with mitigation and adaptation Nations that reduce deforestation will be rewarded China and India will reduce emissions (in principle)

Will emissions cuts hurt the economy? The U.S. Senate, China, and India feel reducing emissions will hurt the economy Economic vitality does not need higher emissions Germany, England, and France cut emissions while keeping a high standard of living Industrialized nations gain from developing and marketing new technologies The future belongs to nations willing to act now

States and cities are advancing policies The U.S. federal government is not acting So state and local governments are The Mayors Climate Protection Agreement Will meet or beat Kyoto’s guidelines California’s Global Warming Solutions Act will cut emissions 25% by 2020 Regional Greenhouse Gas Initiative (RGGI) (2007) 10 northeastern states Set up a cap-and-trade program

Market mechanisms address climate change Permit trading programs harness the economic efficiency of the free market to achieve public policy goals Businesses have flexibility in how they meet the goals Polluters choose how to cut their emissions They have financial incentives to reduce them

Cap-and-trade emissions trading programs The Regional Greenhouse Gas Initiative: Each state decides which polluting sources participate Each state sets a cap on total CO2 emissions it allows Each emissions source gets one permit for each ton it emits, up to the amount of the cap Each state lowers its cap over time Sources with too few permits must reduce emissions, buy permits from others, or pay for carbon offsets Sources with too many permits may sell them Any source emitting more than permitted will be penalized

Cap-and-trade programs already exist Cap-and-trade programs will be self-sustaining Permit prices fluctuate in the market The European Union Emission Trading Scheme (2005) The world’s largest cap-and-trade program Governments had allocated too many permits Industries had little incentive to cut emissions Permits lost 90% of their value The EU is trying to fix these problems Permits work only if government policies limit emissions

Carbon taxes are another option Critics say cap-and-trade systems are not effective Carbon tax: governments charge polluters a fee for each unit of greenhouse gases they emit Polluters have a financial incentive to reduce emissions European nations, British Columbia, and Boulder, Colorado, have carbon taxes However, polluters pass costs on to consumers Fee-and-dividend: funds from the carbon tax (fee) are passed to taxpayers as refunds (dividends)

Carbon offsets are popular Carbon offset: payment to another entity to reduce the greenhouse emissions that one is unable to reduce oneself The payment offsets one’s own emissions Popular among utilities, businesses, universities, governments, and individuals trying to achieve … Carbon-neutrality: where no net carbon is emitted Carbon offsets fall short Rigorous oversight is needed to make sure that the offset money accomplishes what it is intended for Offsets must fund emissions reductions that would not occur otherwise

Corporations are going carbon-neutral Businesses are using carbon offsets to become more sustainable But they can also directly reduce their carbon footprint Pearson Education became carbon neutral in 2009 12% savings: energy-efficient buildings, computer servers, vehicles, reducing business travel 47% savings: buying clean, renewable energy 41% savings: forest preservation projects around the world

Should we engineer the climate? Geoengineering: drastic, assertive steps to change Earth’s climate Suck carbon out of the air by planting trees, fertilizing the ocean with iron Block sunlight with dust, seeding clouds, installing mirrors on land, on sea, and in space These solutions are technically daunting, are decades away, and have unexpected environmental risks Be careful of hoping for easy technological solutions Use geoengineering as a back-up plan

Cooling the planet through geoengineering

You can reduce your carbon footprint Carbon footprint: the amount of carbon we are responsible for emitting People may take many steps to decrease their footprint College students must help drive personal and societal changes needed to mitigate climate change In 2009, 5,200 events were held in 181 nations “The most widespread day of political action in the planet’s history” Global climate change is our biggest challenge With action, we can avert the most severe impacts

Conclusion Many factors influence Earth’s climate Human activities play a major role Climate change is well underway Further greenhouse gas emissions will cause severe impacts More and more people are urging immediate action Reducing emissions and mitigating and adapting to a changing climate are the foremost challenges for our society