© 2010 Pearson Education Canada

14Global Climate Change

PowerPoint® Slides prepared by Thomas Pliske, Heidi Marcum, and Nicole Lantz

This lecture will help you understand:

• The Earth’s climate system

• Human influences on the atmosphere and climate

• Methods of climate research

• Impacts of global climate change

• Ways we can respond to climate change

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But first a brief video: http://www.greenpeace.org.uk/blog/climate/wake-freak-out-20080916

Central Case: Rising seas may flood the Maldives

• The Maldives Islands could be submerged by the rising seas that are accompanying global climate change

• The government has already evacuated residents from of the lowest-lying islands

• Salt water may contaminate drinking water

• The potential of increased damage from natural events such as the 2004 tsunami (caused by an earthquake)

“We’re in a giant car heading towards a brick wall and everyone’s arguing over where they’re going to sit.”

– David Suzuki

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Our dynamic climate

• Climate influences everything around us

• The Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) made it clear that:

- Climate is changing, we are the cause, and this change is already exerting impacts that will become increasingly severe

• Al Gore’s movie An Inconvenient Truth has been seen by millions

• Climate change is the fastest-moving and most pivotal area of environmental science today

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What is climate change?• Climate = an area’s long-term atmospheric conditions

- Temperature, moisture content, wind, precipitation, etc.

• Weather = conditions at localized sites over hours or days

• Global climate change = describes trends and variations in Earth’s climate

- Temperature, precipitation, storm frequency

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

- Earth’s climate has varied naturally through time

- The rapid climatic changes taking place now are due to human activity: fossil fuels, combustion, and deforestation

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The Sun and atmosphere keep Earth warm• Three factors exert more influence on climate than all

others:

- The Sun (supplies planet’s energy)

- The atmosphere (absorbs 70% of incoming solar radiation)

- The oceans (shape climate by storing and transporting heat and moisture, as well as storing CO2)

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Our planet absorbs solar radiation

FIGURE 14.1

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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, chlorofluorocarbons (CFCs)

- Greenhouse gases differ in their ability to warm the troposphere and surface

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The greenhouse effect• After absorbing radiation, greenhouse gases re-emit

infrared energy

- Some energy is lost to space

- Greenhouse effect = some energy travels back downward, warming the troposphere and the planet’s surface

• Global warming potential = the relative ability of one molecule of a given greenhouse gas to contribute to warming

- Expressed in relation to carbon dioxide (potential = 1)

- Nitrous oxide is 296 times as potent as carbon dioxide

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Carbon dioxide is the anthropogenic greenhouse gas of primary concern

• Not the most potent greenhouse gas, but it is extremely abundant

- The major contributor to global warming

• Human activities have boosted atmospheric concentrations from 280 parts per million (ppm) to 387 ppm in 2008

FIGURE 14.2

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Human activity has released carbon from sequestration in long-term reservoirs

• Human activities accelerate the fluxes of material from one reservoir to another in biogeochemical cycles

- Burning fossil fuels transfers CO2 from lithospheric reservoirs into the atmosphere

- Deforestation transfers CO2 from terrestrial biospheric reservoirs into the atmosphere

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Other greenhouse gases contribute to warming

• Methane from fossil fuel deposits, livestock, landfills, the melting permafrost, and crops such as rice

• Nitrous oxide from feedlots, chemical manufacturing plants, auto emissions, and synthetic nitrogen fertilizers

• Ozone from photochemical smog

• Halocarbons (CFCs and HFCs)

• Water vapor = the most abundant greenhouse gas and contributes most to the greenhouse effect

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There are many feedback cycles in the climate system

• Positive feedback cycle

- Warming leads to water vapour which leads to further warming causing still more evaporation, and so on (ditto with the albedo effect in the polar regions)

• Negative feedback cycle

- Warming leads to evaporation which leads to water vapour causing increased cloudiness slowing global warming

• Aerosols = microscopic droplets and particles that have either a warming or cooling effect

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Radiative forcing expresses change in energy input over time

• Radiative forcing = the amount of change in energy that a given factor causes

- Positive forcing warms the surface; negative forcing cools it

• Compared with the pre-industrial Earth, Earth is experiencing radiative forcing of 1.6 watts/m2

- Enough to alter the climate

FIGURE 14.3

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The atmosphere is not the only factor that influences climate• Milankovitch cycles = periodic changes in Earth’s

rotation and orbit around the Sun

• Solar output = drives temperature change on Earth’s surface

• Ocean circulation = ocean water exchanges tremendous amounts of heat with the atmosphere, and ocean currents move energy from place to place

• Ocean absorption = the ocean holds 50 times more carbon than the atmosphere and absorbs it from the atmosphere

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Milankovitch cycles

FIGURE 14.414-16

Currents move north, cool and sink, forming the North Atlantic Deep Water (NADW)

FIGURE 14.6

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• Proxy indicators = types of indirect evidence that serve as substitutes for direct measurements

- Ice caps, ice sheets, and glaciers hold clues to past climate

- Trapped bubbles in ice cores show atmospheric composition, greenhouse gas concentration, temperature trends, snowfall, solar activity, and frequency of fires

Proxy indicators tell us about the past

FIGURE 14.714-18

Stable isotope geochemistry is a powerful tool for the study of paleoclimate

• Stable isotope geochemistry = studying stable isotopes of elements

• Fractionation = separation and differential concentration of isotopes of slightly different mass

• Proxy indicators like stable isotopes often give us information about local or regional areas; scientists then combine multiple records from various areas

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Direct atmospheric sampling tells us about the present

Trends in atmospheric concentrations of carbon dioxide show that concentrations have increased from 315 ppm in 1958 to 387 ppm in 2008

FIGURE 14.8

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Models help us understand climate

• Coupled general circulation model simulate climate

• Use information about:- atmospheric

circulation- ocean

circulation- interactions- feedback

mechanisms

FIGURE 14.9

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Scientists test climate models by entering climate data from past years

FIGURE 14.10

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Current and future trends and impacts

• Evidence that climate conditions have changed since industrialization is now overwhelming and indisputable

• The way each of us experiences these impacts will vary tremendously

• The impacts on Canada could be particularly severe, although they are already being felt severely in the form of drought in Australia and East Africa, and in increased tropical storms wreaking havoc in many developing nations.

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The IPCC summarizes evidence of climate change and predicts future impacts

• Trend = a pattern that persists within a data set, even after short-term fluctuations and anomalies have been accounted for

• Intergovernmental Panel on Climate Change (IPCC)

- 2007: Fourth Assessment Report

- Consensus of scientific climate research from around the world

- trends in surface temperature, precipitation patterns, snow and ice cover, sea levels, storm intensity, and other factors

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Temperature increases will continue• The IPCC report concludes that average surface temperatures

on earth have been rising since 1906, with most of the increase occurring in the last few decades

FIGURE 14.1214-25

The Arctic has borne the brunt of climate change’s impacts

FIGURE 14.1314-26

Climate change and human rights

North America’s Inuit sent a legal petition, demanding that the U.S. restrict its greenhouse gas emissions. After a year, the commission dismissed the petition with a terse three-sentence letter. • Do you think Arctic-living people deserve compen- sation from industrialized nations whose emissions have caused climate change that has disproportionately affected the Arctic? • Do you think climate change can be viewed as a human rights issue? • What ethical issues, if any, do you think climate change presents? How could these best be resolved?

weighing

the issues

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Changes in precipitation vary by region

• 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 drinking water supplies, and encouraging forest fires

• Heavy rains have contributed to flooding

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Projected increases in surface temperature

• More frequent heat waves

• Temperature change will vary by region

• Stronger storms

FIGURE 14.14

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Projected changes in June-August precipitation

FIGURE 14.15

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Melting snow and ice have far-reaching effects

• Mountaintop glaciers are disappearing

- In Glacier National Park, only 27 of 150 glaciers remain

- Risks of sudden floods as ice dams burst

- Reduction in summertime water supplies

• Melting of the Greenland ice sheet is accelerating

• As ice melts, darker, less-reflective surfaces are exposed and absorb more sunlight, causing more melting

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Glaciers are melting rapidly around the world

FIGURE 14.16

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The Arctic is changing dramatically

• Less snow cover

• Melting immense ice sheets

• Canada’s ice shelves have shrunk by 90% over the past 100 years

• Warming is accelerating

- as snow and ice melt, darker, less-reflective surfaces are exposed

- Earth’s capacity to reflect light decreases

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Rising sea levels will affect hundreds of millions of people and coastal zones

• As glaciers and ice melt, increased water will flow into the oceans

• As oceans warm, they expand

FIGURE 14.20

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An ice-free Northwest Passage and Canada’s Arctic sovereignty

Canada reaffirmed its sovereignty over Arctic waters in 2008. The Arctic subsurface may hold as much as 25% of the world’s undiscovered oil and gas reserves.

• The U.S. argues that the High Arctic does not belong to Canada, or to anyone else. What do you think? • Who should control Arctic Ocean waters, and for what purposes? • How much of Canadian taxpayers’ money should be spent to assert and maintain Canada’s sovereignty in the Arctic?

weighing

the issues

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Climate change affects organisms and ecosystems• Global warming modifies temperature-dependent

phenomena

- Timing of migration, breeding

• Spatial shifts in the range of organisms

- Animals and plants will move towards the poles or upward in elevation

- 20-30% of all species will be threatened with extinction

• Plants act as carbon sinks; fewer plants means more CO2 in the atmosphere

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Climate change exerts societal impacts – and vice versa• Agriculture:

- growing seasons shortened, crops more susceptible; crop production will decrease, worsening hunger

• Forestry:

- increased insect and disease outbreaks, increased chance of forest fires

• Health:

- heat waves can cause death, respiratory ailments, expansion of tropical diseases and insect pests, increased chance of drowning if storms become intense, hunger-related ailments

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Agriculture for a warmer world

The IPCC predicts that slight warming could shift agri- cultural belts toward the poles and marginally increase global crop production.

• How might this shift affect Canada’s North? • How would a poleward shift of agriculture affect Russia and Argentina? India, Nigeria, and Ethiopia?• If climate change magnifies inequities between developed and developing nations, what could we do to alleviate this problem? Also: given that developed nations have been the main ones to benefit from warming, how should the burden of addressing being portioned out?

weighing

the issues

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Are we responsible for climate change?

• The IPCC concluded:- It is more than 90% likely that most of the global

warming recorded over the past 50 years is due to the well-documented increase in greenhouse gas concentrations in our atmosphere

• Today the debate concerning the human role in climate change is largely over

• However, there may not have been a corresponding shift in public perception

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Responding to climate change

• Four groups of potential scenarios of human response to climate change

- A1: rapid economic growth, mid-century peak in population, rapid introduction of efficient technologies

- B1: service- and information- based economy, mid-century peak in population

- B2: intermediate population and economic growth, local solutions to sustainability

- A2: high population growth, slow economy, slow adoption of efficient technologies

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Shall we pursue mitigation or adaptation?

• Mitigation = pursue actions that reduce greenhouse gas emissions, in order to lessen severity of future climate change

- Renewable energy sources, farm practices to protect soil integrity, preventing deforestation

• Adaptation = accept climate change is happening and pursue strategies to minimize its impacts on us

- Criticized as sidestepping

• Both are arguably necessary; even if we get aggressive with mitigation, the climate will still warm

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We can look more closely at our lifestyles

• Conservation and efficiency

- High-efficiency light bulbs and appliances

- Reduce electricity consumption

- Life-style choices

• Sources of electricity

- Alter types of energy we use

- Natural gas cleaner than oil; oil cleaner than coal

• Carbon capture and storage = remove CO2 from power plant emissions

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Nuclear power or fossil fuels

Some environmentalists support the use of nuclear power for the generation of electricity, since it is a “clean” energy source that does not add to greenhouse gas emissions or other types of air pollution.

Others oppose it fiercely, citing problems with the disposal of highly toxic and radioactive waste, among other reasons.

- What do you think about nuclear energy? - Is it an “environmental” choice?

weighing

the issues

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Transportation is a significant source of greenhouse gases

• Automotive technology

• make vehicles more fuel-efficient, hybrid cars

• Driving less and using public transportation

- Public transportation is the most effective way to conserve energy, reduce pollution

- Live nearer your workplace, so you can bike or walk

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Conventional cars are extremely inefficient

FIGURE 14.28

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We can reduce emissions in other ways as well

• Use advances in agriculture, forestry, and waste management

- Grow renewable biofuels

- Rapid reforestation of deforested areas

- Recovering methane from landfills

- Recycling, composting, and reduction or reuse of materials

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We will need to follow multiple strategies to reduce emissions

• There is no single magic bullet for mitigating climate change

• Most reductions can be achieved using current technology so we can begin right away

• How quickly and successfully we translate science and technology into practical solutions for reducing emissions depends on policies and the market economy

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We began tackling climate change by international treaty

• UN Framework Convention on Climate Change (FCCC) = outlines a plan for reducing greenhouse gas emissions to 1990 levels by the year 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 that would require all signatory nations to reduce their emissions

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The Kyoto Protocol seeks to limit emissions

• The Kyoto Protocol

- by 2012 nations must reduce emissions of six greenhouse gases to levels below those of 1990

- took effect in 2005, after Russia became the 127th nation to ratify it

• The United States will not ratify the Kyoto Protocol

• Businesses in industrialized nations feel they have more to lose economically from restrictions

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• Permit trading programs

- harness the economic efficiency of the free market to achieve policy goals

- The Chicago Climate Exchange is the world’s first emissions trading program for greenhouse gas reduction

• Cap-and-trade programs

- European Union Emission Trading Scheme

Market mechanisms are being used to address climate change

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Carbon offsets are in vogue

• Carbon offset = a voluntary payment to another entity intended to enable that entity to reduce the greenhouse emissions that one is unable or unwilling to reduce oneself - Popular among utilities, businesses, universities,

governments, and individuals trying to achieve

• Carbon-neutrality = no net carbon is emitted (schools, universities, and municipalities are now required by BC law to be climate-neutral)

• Carbon offsets fall short - A lack of oversight to make sure that the offset money

accomplishes what it is intended for

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You can reduce your own carbon footprint

• Carbon footprint = expresses the amount of carbon we are responsible for emitting

• Global climate change may be the biggest challenge facing us and our children

- Taking immediate action is the most important thing we can do

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Conclusion

• Many factors influence Earth’s climate

- Human activities play a major role

• Climate change is well underway

- Further emissions will cause severe impacts

• More and more scientists are urging immediate action

- Reducing emissions

- Mitigating and adapting to a changing climate

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QUESTION: Review

“Climate” is defined as….

a) Conditions at localized sitesb) Conditions over hours or days– An area’s long-term atmospheric conditionsa) Variations in Earth’s temperature

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QUESTION: Review

“Global potential,” when referring to greenhouse gases, means….

a) The ability of a molecule to contribute to global warming

b) The ability of a molecule to prevent global warmingc) Carbon dioxide is the most potent greenhouse gasd) Energy travels back to the Earth, after being emitted

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QUESTION: ReviewWhich of the following are major contributors of global warming?

a) Burning fossil fuels and recyclingb) Burning fossil fuels and deforestationc) Deforestation and nuclear energyd) Fossil fuels and nuclear energy

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QUESTION: ReviewA “proxy indicator” is ….

a) Indirect evidenceb) Indirect evidence that substitutes for direct

evidencec) Direct evidenced) Direct evidence that substitutes for indirect

evidence

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QUESTION: Review

What happens as ice melts in polar regions?

a) More heat is reflected into spaceb) Glaciers re-freeze at nightc) Exposed soils absorb heat and make melting

worsed) Polar bears learn to like the Sun

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QUESTION: Interpreting Graphs and Data

According to this model, which area will have increased droughts and starvation?

a) Canadab) The tip of South Americac) North Africad) Greenland

FIGURE 14.15

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QUESTION: Interpreting Graphs and Data

Which statement is supported by this figure?

• CO2 emissions have stabilized recently

• CO2 emissions fluctuate only in Hawaii

• CO2 emissions have increased drastically

• CO2 emissions average 320 ppm

[see also:

http://vimeo.com/1709110]FIGURE 14.8

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