Download What is climate change?

14
Global Climate Change
PowerPoint® Slides prepared by
Thomas Pliske, Heidi Marcum, and Nicole Lantz
© 2010 Pearson Education Canada
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
But first a brief video:
http://www.greenpeace.org.uk
/blog/climate/wake-freak-out20080916
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Central Case: Rising seas may flood the
Maldives
“We’re in a giant car heading towards a brick wall and
everyone’s arguing over where they’re going to sit.”
– David Suzuki
• 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)
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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 preindustrial 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 14.4
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Currents move north, cool and sink, forming
the North Atlantic Deep Water (NADW)
FIGURE 14.6
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Proxy indicators tell us about the past
• 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
FIGURE 14.7
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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 14.12
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The Arctic has borne the brunt of climate
change’s impacts
FIGURE 14.13
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weighing
issues
the
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 compensation 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?
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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
FIGURE 14.14
• More frequent heat waves
• Temperature change will vary by region
• Stronger storms
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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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weighing An ice-free Northwest Passage
issues and Canada’s Arctic sovereignty
the
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?
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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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weighing
issues
the
Agriculture for a warmer world
The IPCC predicts that slight warming could shift agricultural 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?
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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, midcentury 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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weighing
Nuclear power or fossil fuels
issues
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.
the
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?
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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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Market mechanisms are being used to
address climate change
• 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
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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)
b)
–
a)
Conditions at localized sites
Conditions over hours or days
An area’s long-term atmospheric conditions
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 warming
c) Carbon dioxide is the most potent greenhouse gas
d) Energy travels back to the Earth, after being emitted
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QUESTION: Review
Which of the following are major contributors of global
warming?
a)
b)
c)
d)
Burning fossil fuels and recycling
Burning fossil fuels and deforestation
Deforestation and nuclear energy
Fossil fuels and nuclear energy
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QUESTION: Review
A “proxy indicator” is ….
a) Indirect evidence
b) Indirect evidence that substitutes for direct
evidence
c) Direct evidence
d) 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 space
b) Glaciers re-freeze at night
c) Exposed soils absorb heat and make melting
worse
d) 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?
FIGURE 14.15
a) Canada
b) The tip of South America
c) North Africa
d) Greenland
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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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