© 2012 Pearson Education, Inc. Global Climate Change Chapter 14

© 2012 Pearson Education, Inc.

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


• Tourists think the Maldives Islands are a paradise• Rising seas due to global climate change could submerge them

o Flood areas, erode beacheso Damage coral reefs

• Residents have evacuated the lowest-lying islands

• Small nations do not cause of climate changeo Yet they suffer

Central Case Study: Rising Seas May Flood the

Maldives


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

o Temperature, precipitation, wind, humidity, etc. o Weather: short-term conditions at localized sites

• Global climate change: describes modifications in Earth’s climateo Temperature, precipitation, storm frequency

• Global warming and climate change are not the same


Global warming• Global warming: an increase in Earth’s average temperature

o Only one aspect of climate change

• Earth’s climate has varied naturally through timeo Today’s climate change is happening at an extremely rapid rateo 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 frozeno It supplies most of Earth’s energy

• The atmosphere: without it, Earth’s temperature would be much coldero Clouds, land, ice, and water absorb 70% of incoming solar radiationo 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 radiationo Water vapor, ozone, carbon dioxide, nitrous oxide, methane, halocarbons

(chlorofluorocarbons [CFCs])

• Greenhouse gases re-emit infrared energyo Some energy is lost to spaceo 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 warmingo Expressed in relation to carbon dioxide (potential = 1)o Nitrous oxide is 298 times as potent as carbon dioxide

• Carbon dioxide contributes most to the greenhouse effecto It is less potent, but far more abundant, than other gaseso The major type of human-caused emissions


Greenhouse gas concentrations are rising

• The greenhouse effect is naturalo Greenhouse gases have always been in the atmosphere

• We are concerned with the anthropogenic (human-caused) intensification of the greenhouse effecto 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!)o The highest in 800,000 (possibly 20 million) years






U.S. emissions of major greenhouse gases


• Burning fossil fuels transfers CO2 from underground deposits into the atmosphere o The main reason CO2 levels have increased

• Deforestation contributes to rising atmospheric CO2

o Plants store carbon in their tissueso Less CO2 is

absorbed from the atmosphere

Why have CO2 levels risen so rapidly?



Other greenhouse gases are increasing

• Methane: fossil fuels, livestock, landfills, crops (rice)o Levels have increased 2.5 times since 1750

• Nitrous oxide: feedlots, chemical manufacturing plants, auto emissions, and synthetic nitrogen fertilizerso Risen 18% since 1750

• Ozone levels have risen 36% due to photochemical smogo The Montreal Protocol has reduced halocarbons (CFCs)

• Water vapor: the most abundant greenhouse gas o Contributes most to the natural greenhouse effecto But concentrations have not changed


Natural factors affecting climate

Section 2


Most aerosols exert a cooling effect

• Aerosols: microscopic droplets and particles o They have either a warming or a cooling effect

• Soot (black carbon aerosols) causes warming by absorbing solar energy o 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 termo 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 causeso Positive forcing warms

the surfaceo 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 suno Alter the way solar

radiation is distributed over Earth

• These cycles modify patterns of atmospheric heatingo Triggering climate

variation o Glaciation: cold

temperatures and ice sheets



Solar output and oceans influence climate

• Solar output: the sun varies in the radiation it emitso Variation in solar energy (e.g., solar flares) has not been great enough to change Earth’s

temperatureo Radiative forcing is 0.12 watts/m2 —less than any human causes

• Ocean absorption: oceans hold 50 times more carbon than the atmosphere o Slows global warming but does not prevent ito As oceans warm, they absorb less CO2, accelerating warming


Ocean circulation influences climate

• Ocean circulation: ocean water exchanges heat with the atmosphereo Currents move energy from place to place

• The ocean’s thermohaline circulation system affects regional climateso Moving warm tropical water north, etc.o Greenland’s melting ice sheet will affect this flow

• El Niño and La Niña events change regional weathero Dry areas get wetter, while wet areas get dryer


How did we figure this all out?

Section 3


• 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

Proxy indicators tell us about the past


800,000 years of history in an ice core (Vostok Ice Core-National Ice Core)

Trapped bubbles contain samples of ancient air

Concentrations of gas are correlated with temperature


Core Freezer!

• National Ice Core Laboratory

• Longest core to date is over 3,400meters and dates back 68,000years from the West Antarctic Divide Ice Sheet!

Ice Core shows volcanic ash


Direct measurements tell us about the present

• We document daily fluctuations in weathero 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…o 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 o To simulate climate processes

• If a model accurately reconstructs current climateo 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 everywhereo Fishermen in the Maldives, ranchers in Texas, homeowners in Florida, etc.

• We cannot blame any single weather event on climate changeo 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 1988o 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 1906o Most of the increase occurred in the last few decadeso The 17 warmest years on record have been since 1990o 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 0.4C• At the end of the 21st century, temperatures will be 1.8 to

4.0C higher than today’so We will have unusually hot days and heat waves

• Polar areas will have the most intense warming• Sea surface temperatures will rise

o 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 o Other areas are receiving less

• In the U.S. Southwest, droughts have become more frequent and severeo Harm agriculture, promote soil erosion, reduce water supplies, and trigger fires

• In dry, humid regions, heavy rains cause floodingo Kill people, destroy homes, and inflict billions of dollars in damageo 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 disappearingo Glaciers on tropical mountaintops have disappearedo The remaining 26 of 150 glaciers in Glacier National Park will be gone by 2030o Reducing summertime water supplies to millions

• Melting of Greenland’s Arctic ice sheet is accelerating• Warmer water is melting Antarctica’s coastal ice shelves

o 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

o 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

o 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 levelo Caused by the high tides and winds of storms

• A 2004 earthquake caused a tsunami (tidal wave) that killed 100 Maldives residents o Caused $470 million in damages

• Cities will be floodedo 53% of people in the U.S. live in coastal areas

• Vulnerability to storm surges will increaseo 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 areaso Many will have to invest in costly efforts to protect against high tides and storm surges

• Areas that will be most affected include:o Densely populated, poor regions (e.g., Bangladesh)o Storm-prone regions (e.g., Florida)o Coastal cities (e.g., Houston)o Areas with land subsidence (e.g., U.S. Gulf Coast)o 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 bleachingo Which kills corals

• Ocean acidification: caused by increased CO2

o Organisms can’t build their exoskeletons

• Oceans have already decreased by 0.1 pH unito 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 environmentso 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 elevationo 20–30% of species will be threatened with extinctiono Rare species will be pushed out of preserves

• More CO2 may increase plant growth, but…

• Droughts, fire, and disease will decrease plant growtho Fewer plants means more CO2 in the atmosphere


Animals and plants have nowhere to goAnimals 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 o Increasing hunger in many developing nations

• Forestry: increased fires, invasive specieso Insect and disease outbreaks

• Health: heat waves and stress can cause deatho Respiratory ailments, expansion of tropical diseaseso Disease and sanitation problems from floodingo Drowning from storms


Climate change affects economics

• Costs will outweigh benefits of climate change• It will widen the gap between rich and poor

o Those with less wealth and technology will suffer most

• It will cost 1–5% GDP (Gross Domestic Product) on average globally o 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 2200o 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:o Temperature increases (2.2 – 6.1C higher)

o Worse droughts and floodingo Decreased crop yieldso Water shortageso Health problems and diseaseso Higher sea levels, beach erosion, destroyed wetlandso Drought, fire, and pests will change forestso More grasslands and deserts, fewer forestso 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 warmingo Burning fossil fuels is increasing greenhouse gases

• Despite overwhelming evidence for climate change:o Many in the U.S. deny what is happeningo People debate if it is real and if humans are to blameo Think tanks and a few scientists question ito The news media present both sides, despite the evidence of climate changeo 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 Eartho They are searching for solutions

• Mitigation: pursue actions that reduce greenhouse gas emissions to lessen the severity of climate changeo Energy efficiency, renewable energy, protecting soil, preventing deforestation

• Adaptation: accept that climate change is happening o Pursue strategies to minimize its impacts on uso Seawalls, coping with drought and less water, etc.

• We need to pursue both


SolutionsSection 6


Developing solutions

• Electrical generation: the largest source of U.S. CO2

o 70% of electricity is from fossil fuels, especially coal

• To reduce fossil fuel use: o Conservation, efficiency, cleaner or renewable energyo Cogeneration, more efficient appliances

• Carbon capture: removes CO2 from power plant emissions

• Carbon sequestration (storage): storing carbon underground (old oil deposits, salt mines, etc.)o We can’t store enough CO2 to make a difference


Transportation• 2nd largest source of U.S. greenhouse gases

o Cars are extremely inefficient

• Solutions: drive fuel-efficient, hybrid, or electric cars o Drive less and use public transportationo 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 changeReductions can be achieved with technology we can use right away

Just 15 strategies can eliminate 15

billion tons of CO2 by 20507 of the 15 would stabilize CO2 emissions


What role should government play?

• To reduce emissions, should the government:o Mandate change through laws and regulations?o Impose no policies and hope for solutions?o Give private entities incentives to reduce emissions?

• Many businesses and politicians have opposed all government actiono 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 Senateo Industries would compete to reduce emissions for financial gain

• Responsibility for emissions now goes to the EPAo It began developing regulations in 2011o Emission limits will be phased in over years, while increasing efficiency and renewable energyo This will minimize economic impacts and political oppositiono 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 o 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 o 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

o China wouldn’t allow international monitoringo Obama would not promise more than Congress had agreed to

• Cancun’s 2010 meeting was more productiveo Developed nations will help developing nations with technology and with mitigation and

adaptationo Nations that reduce deforestation will be rewardedo China and India will reduce emissions (in principle)


Will emissions cuts hurt the economy?

• The U.S. Senate, China, andIndia 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 actingo So state and local governments are

• The Mayors Climate Protection Agreement o 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 o Businesses have flexibility in how they meet the goals

• Polluters choose how to cut their emissionso They have financial incentives to reduce them


Cap-and-trade emissions trading programs

• The Regional Greenhouse Gas Initiative:o Each state decides which polluting sources participateo Each state sets a cap on total CO2 emissions it allows

o Each emissions source gets one permit for each ton it emits, up to the amount of the capo Each state lowers its cap over timeo Sources with too few permits must reduce emissions, buy permits from others, or pay for carbon

offsetso Sources with too many permits may sell themo Any source emitting more than permitted will be penalized


Cap-and-trade programs already exist

• Cap-and-trade programs will be self-sustainingo Permit prices fluctuate in the market

• The European Union Emission Trading Scheme (2005)o The world’s largest cap-and-trade programo Governments had allocated too many permitso Industries had little incentive to cut emissionso Permits lost 90% of their valueo 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 emito Polluters have a financial incentive to reduce emissionso 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 o The payment offsets one’s own emissions

• Popular among utilities, businesses, universities, governments, and individuals trying to achieve … o Carbon-neutrality: where no net carbon is emitted

• Carbon offsets fall short o Rigorous oversight is needed to make sure that the offset money accomplishes what it is intended

for o Offsets must fund emissions reductions that would not occur otherwise


Corporations are going carbon-neutral

• Businesses are using carbon offsets to become more sustainableo But they can also directly reduce their carbon footprint

• Pearson Education became carbon neutral in 2009o 12% savings: energy-efficient buildings, computer servers, vehicles, reducing business travelo 47% savings: buying clean, renewable energyo 41% savings: forest preservation projects around the world


Should we engineer the climate?

• Geoengineering: drastic, assertive steps to change Earth’s climateo Suck carbon out of the air by planting trees, fertilizing the ocean with irono 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 riskso Be careful of hoping for easy technological solutionso 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

o “The most widespread day of political action in the planet’s history”

• Global climate change is our biggest challengeo With action, we can avert the most severe impacts


Conclusion

• Many factors influence Earth’s climateo Human activities play a major role

• Climate change is well underwayo 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

Documents

© 2012 Pearson Education, Inc. Global Climate Change Chapter 14