© 2011 Pearson Education, Inc. Lecture Outlines Chapter 18 Environment: The Science behind the...
Transcript of © 2011 Pearson Education, Inc. Lecture Outlines Chapter 18 Environment: The Science behind the...
© 2011 Pearson Education, Inc.
Lecture Outlines
Chapter 18
Environment:The Science behind the Stories
4th Edition
Withgott/Brennan
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What is climate change?
• Climate change is the fastest-developing area of environmental science
• Climate = an area’s long-term atmospheric conditions- Temperature, moisture, wind, precipitation, etc. - Weather = short-term conditions at localized sites
• Global climate change = describes trends and variations in Earth’s climate- Temperature, precipitation, storm frequency
• Global warming and climate change are not the same
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Global warming
• Global warming = an increase in Earth’s average temperature- Only one aspect of climate change
• Climate change and global warming refer to current trends- Earth’s climate has varied naturally through time
• The current rapid climatic changes are due to humans- Fossil fuel combustion and deforestation
• Understanding climate change requires understanding how our planet’s climate works
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The sun and atmosphere keep Earth warm
• Four factors exert the most influence on climate• The sun = without it, Earth would be dark and frozen
- Supplies most of Earth’s energy• The atmosphere = without it, Earth’s temperature would
be much colder• The oceans = shape climate by storing and transporting
heat and moisture• How Earth spins, tilts, and moves through space
influence how climate varies over long periods of time
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The fate of solar radiation• The atmosphere, land, ice, and water absorb 70% of
incoming solar radiation
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Greenhouse gases warm the lower atmosphere
• As Earth’s surface absorbs solar radiation, the surface increases in temperature and emits infrared radiation
• Greenhouse gases = atmospheric gases that absorb infrared radiation- Water vapor, ozone, carbon dioxide, nitrous oxide,
methane, halocarbons [chlorofluorocarbons (CFCs)]• After absorbing radiation, greenhouse gases re-emit
infrared energy, losing some energy to space • Greenhouse effect = energy that travels downward,
warming the atmosphere and the planet’s surface
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The greenhouse effect is natural
• Greenhouse gases have always been in the atmosphere• We are not worried about the natural greenhouse effect• 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)- Methane is 25 times as potent as carbon dioxide
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Carbon dioxide is of primary concern
• It is not the most potent greenhouse gas, but it is extremely abundant- The major contributor to the greenhouse effects
• CO2 exerts six times more impact than methane, nitrous oxide, and halocarbons combined
• Deposition, partial decay, and compression of organic matter (mostly plants) in wetlands or marine areas led to formation of coal, oil, and natural gas- These deposits remained buried for millions of years
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• Burning fossil fuels transfer CO2 from lithospheric reservoirs into the atmosphere - The main reason atmospheric carbon dioxide
concentrations have increased so dramatically
• Deforestation contributes to rising atmospheric CO2
- Forests serve as reservoirs for carbon- Removing trees reduces the carbon dioxide absorbed
from the atmosphere
• Human activities increased atmospheric CO2 from 280 parts per million (ppm) to 389 ppm- The highest levels in more than 800,000 years
What caused levels of CO2 to increase?
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Fluxes of carbon dioxide
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Other greenhouse gases add to warming
• Methane = fossil fuels, livestock, landfills, crops (rice)- Levels have doubled since 1750
• Nitrous oxide = feedlots, chemical manufacturing plants, auto emissions, and synthetic nitrogen fertilizers
• Ozone levels have risen 36% due to photochemical smog• Halocarbon gases (CFCs) are declining due to the
Montreal Protocol• Water vapor = the most abundant greenhouse gas
- Contributes most to the natural greenhouse effect- Concentrations have not changed
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U.S. emissions of major greenhouse gases
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Milankovitch cycles 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 - For example, periods of cold
glaciation and warm interglacial times
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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–Southern Oscillation (ENSO)- Shifts atmospheric pressure, sea surface
temperature, ocean circulation in the tropical Pacific
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Direct measurements tell us about the present
• We document daily fluctuations in weather- Precise thermometer measurements over the past 100
years
• Measuring of ocean and atmospheric chemistry began in 1958
• Precise records of historical events- Droughts, etc.
Atmospheric CO2
concentrations have increased from 315 ppm to 389 ppm
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Ice cores from Antarctica
• Ice cores let us go back in time 800,000 years- Reading Earth’s history across eight glacial cycles
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More proxy indicators
• Cores in sediment beds preserve pollen grains and other plant remnants
• Tree rings indicate age, precipitation, droughts, and fire history
• In arid regions, packrats carry seeds and plants to their middens (dens)- Plant parts can be preserved for centuries
• Researchers gather data on past ocean conditions from coral reefs
• Scientists combine multiple records to get a global perspective
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Temperatures continue to increase• Average surface temperatures increased 0.74 °C since
1906- Most of the increase occurred in the last few decades- Extremely hot days have increased- The 16 warmest years on record have been since 1990
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The future will be hotter
• In the next 20 years, temperatures will rise 0.4 °C• At the end of the 21st century, temperatures will be 1.8–
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
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Temperatures will rise globally
Projected increases in surface temperature for 2090–2099 relative to 1980–1999
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Precipitation is changing, too
• Some regions are receiving more precipitation than usual, and others are receiving less
• Droughts have become more frequent and severe- Harming agriculture, promoting soil erosion,
reducing water supplies, and triggering fires• Heavy rains contribute to flooding
- Killing people, destroying homes, and inflicting billions of dollars in damage
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Projected changes in precipitation
Precipitation will increase at high latitudes and decrease at low and middle latitudes
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Melting snow and ice
• Mountaintop glaciers are disappearing- Glaciers on tropical mountaintops have disappeared- The remaining 26 of 150 glaciers in Glacier National
Park will be gone by 2020 or 2030- Reducing summertime water supplies
• Melting of Greenland’s Arctic ice sheet is accelerating• Warmer water is melting Antarctic coastal ice shelves
- Interior snow is increasing due to more precipitation• Melting ice exposes darker, less-reflective surfaces,
which absorb more sunlight, causing more melting
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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
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Rising sea levels
• Runoff from melting glaciers and ice will cause sea levels to rise
• As oceans warm, they expand- Leading to beach erosion, coastal floods, and
intrusion of salt water into aquifers
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Coastal areas will flood
• Storm surge = temporary, localized rise in sea level- Caused by the high tides and winds of storms
• Cities will be flooded- 53% of people in the U.S. live in coastal areas
An earthquake caused the 2004 tsunami (tidal wave) that killed 100 Maldives residents and caused $470 million in damages
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Rising sea levels will devastate coasts
• 1 million acres of Louisiana’s wetlands are gone- Rising sea levels eat away vegetation- Dams upriver decrease siltation- Pollution from the Deepwater Horizon
• Millions of people will be displaced from coastal areas
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Coral reefs are threatened
• Coral reefs are habitat for food fish - Snorkeling and scuba diving sites for tourism
• Warmer waters contribute to coral bleaching- Which kills corals
• Increased CO2 is acidifying the ocean
- Organisms can’t build their exoskeletons• Oceans have already decreased by 0.1 pH unit
- Enough to kill most coral reefs
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Heat waves will increase
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Impacts of climate change will vary
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The U.S. Global Change Research Program
• In 2009, scientists reported and predicted:- Temperature increases - 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
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Predictions from two climate models
By 2050, Illinois will have a climate like Missouri’s
By 2090, it will have a climate like Louisiana’s
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We need both adaptation and mitigation
• Adaptation: even if we stopped all emissions, warming would continue
• Mitigation: if we do nothing, we will be overwhelmed by climate changes
The faster we reduce our emissions, the less we will alter the climate
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Electricity generation
• The largest source of U.S. CO2 emissions
- 70% of electricity comes from fossil fuels- Coal causes 50% of emissions
• To reduce fossil fuel use: - Encourage conservation and efficiency- Switch to cleaner and renewable energy sources
A coal-fired, electricity-generating power plant
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Conservation and efficiency
• We can make lifestyle choices to reduce electricity use- Use fewer greenhouse-gas-producing appliances- Use electricity more efficiently
• The EPA’s Energy Star Program rates appliances, lights, windows, etc. by their energy efficiency- Replace old appliances with efficient ones- Use compact fluorescent lights- Use efficient windows, ducts, insulation, heating and
cooling systems
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Sources of electricity
• We need to switch to clean energy sources- Nuclear power, biomass energy, solar, wind, etc.
• We need to consider how we use fossil fuels- Switching from coal to natural gas cuts emissions 50%- Cogeneration produces fewer emissions
• Carbon capture = removes CO2 from power plant emissions
• Carbon sequestration (storage) = storing carbon underground where it will not seep out- Use depleted oil and gas deposits, salt mines, etc.
- We can’t store enough CO2 to make a difference
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Transportation
• 2nd largest source of U.S. greenhouse gases- Cars are inefficient
• Ways to help:- More efficient cars- Hybrid or electric cars- Drive less and use
public transportation- Live near your job, so
you can bike or walk
U.S. public transportation saves 4.2 billion gallons of gasoline and 37 million metric tons of CO2 emissions
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Conventional cars are inefficient
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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
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We need to follow multiple strategies
• There is no magic bullet for mitigating climate change• Most reductions can be achieved using current
technology that we can use right away• Stabilization triangle = a portfolio of strategies, each one
feasible in itself, that could stabilize CO2 emissions
- Reducing 1 billion tons of carbon per year for 50 would eliminate one of the seven “wedges”
• This approach is not enough – we need to reduce, not only stabilize, emissions
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Strategies to stabilize CO2 emissions
15 strategies could each take care of one wedge
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The FCCC
• U.N. Framework Convention on Climate Change = a plan to reduce greenhouse gas emissions to 1990 levels by 2000 through a voluntary, nation-by-nation approach
• By the late 1990s, it was clear that the voluntary approach would not succeed
• Developing nations created a binding international treaty requiring emission reductions
• The Kyoto Protocol = between 2008 and 2012, signatory nations must reduce emissions of six greenhouse gases to levels below those of 1990
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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- In 2007, one delegate said, “If for some reason you are
not willing to lead...please get out of the way.”
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The Copenhagen conference
• The conference in 2009 tried to design a successor treaty to the Kyoto Protocol- Nations hoped the U.S., under President Obama,
would participate in a full international agreement• Obama would not promise more than Congress had
agreed to• In a last-minute deal, developed nations will help
developing nations pay for mitigation and adaptation- Nations that reduce deforestation will be rewarded
• Nothing is legally binding and no targets are set
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Will emissions cuts hurt the economy?
• The U.S. Senate feels emissions reductions will hurt the economy
• China and India also resist emissions cuts
• Economic vitality does not need higher emissions- Germany cut emissions by 21%, the U.K. by 17%
• Industrialized nations will gain from energy transitions- They invent, develop, and market new technologies
• The future will belong to nations willing to develop new technologies and energy sources
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Market mechanisms address climate change• Permit trading programs harness the economic efficiency
of the free market to achieve policy goals - Businesses have flexibility in how they meet the goals
• Polluters choose how to cut their emissions- They are given financial incentives to reduce them
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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• Polluters pass costs on to consumers• Fee-and-dividend = funds from the carbon tax (fee) are
passed to taxpayers as refunds (dividends)
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Carbon offsets are popular
• Carbon offset = a voluntary payment intended to enable another entity to reduce the greenhouse emissions that one is unable to reduce oneself - The payments offset 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
- Needs rigorous oversight to make sure that the offset money accomplishes what it is intended for
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You can reduce your carbon footprint
• Carbon footprint = expresses the amount of carbon we are responsible for emitting
• People may apply many strategies to decrease their footprint
• College students must help drive personal and societal changes needed to mitigate climate change
• Global climate change may be the biggest challenge facing us and our children
- With concerted action, we can avert the most severe impacts