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Global Climate Change
Chapter Objectives
This chapter will help students:
Describe Earth’s climate system and explain the many factors influencing
global climate
Characterize human influences on the atmosphere and global climate
Summarize modern methods of climate research
Outline current and future trends and impacts of global climate change
Suggest ways we may respond to global climate change
Lecture Outline
I. Central Case: Rising Seas May Flood the Maldives Under
A. A nation of low-lying islands, or atolls, in the Indian Ocean, the
Maldives is known for its spectacular tropical setting, colorful coral
reefs, and sun-drenched beaches.
B. Nearly 80% of the Maldives’ land area of 300 km2 lies less than 1 m
(39 in.) above sea level, and the highest point of ground is only 2.4 m.
C. The world’s oceans rose 10–20 cm (4–8 in.) this past century, and are
expected to continue to rise as temperatures warm, causing melting ice
caps to discharge water into the ocean.
D. The island’s government has evacuated residents from several of the
lowest-lying islands in recent years.
E. The tsunami in December of 2004 destroyed large sectors of the
islands, including both homes and infrastructure such as hospitals and
modes of transportation.
F. Other effects included soil erosion, saltwater contamination of
aquifers, and other environmental damage.
G. The tsunami was caused by an earthquake, but the rising sea level
allowed it to inflict great damage on the low-lying islands.
H. Maldives islanders are not alone in their worries; the people of other
island nations and mainland coastal areas of the world fear the future.
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II. Our Changing Climate
1. Climate influences everything from daily weather, major storms,
crop success, human health, ecosystem function, and even
national security.
2. The 2007 report from the Intergovernmental Panel on Climate
Change shows wide scientific consensus that global climate is
changing rapidly and human action is the major cause.
A. What is climate change?
1. Climate is an area’s long-term weather.
2. Changes in the long-term pattern of atmospheric conditions
worldwide, involving temperature, precipitation, and storm
frequency and intensity, are global climate change.
3. Global warming refers specifically to increasing surface
temperatures of the Earth and is but one aspect of global climate
change.
B. The sun and the atmosphere keep Earth warm.
1. The sun, the atmosphere, and the oceans exert more influence on
Earth’s climate than all other factors combined.
C. “Greenhouse gases” warm the lower atmosphere.
1. As Earth’s surface absorbs solar radiation, its temperature
increases and it emits radiation in the infrared portion of the
spectrum.
2. Some atmospheric gases absorb infrared radiation effectively and
are known as greenhouse gases.
3. When these gases absorb heat, they warm the atmosphere
(specifically, the troposphere) as well as Earth’s surface. This
warming is known as the greenhouse effect.
4. The greenhouse effect is a natural phenomenon that has been
increased through human activities.
D. Carbon dioxide is the greenhouse gas of primary concern.
1. Although carbon dioxide is not the most potent greenhouse gas on
a per-molecule basis, its abundance in the atmosphere means that
it contributes more to the greenhouse effect than other gases.
2. Carbon dioxide concentrations have increased and are currently at
the highest level in at least 650,000 years if not in the last 20
million years.
3. In the last two centuries humans have been burning increasing
amounts of fossil fuels in their homes, factories, and automobiles.
At the same time we have cleared and burned forests, reducing the
biosphere’s ability to absorb carbon dioxide from the atmosphere.
E. Other greenhouse gases add to warming.
1. Other greenhouse gases are increasing in the atmosphere.
a. We release methane into the atmosphere by tapping into fossil
fuel deposits, raising large herds of cattle, disposing of
organic matter in landfills, and growing certain types of crops,
including rice.
b. Nitrous oxide is a by-product of feedlots, chemical
manufacturing plants, auto emissions, and modern agricultural
practices.
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c. Ozone concentrations in the troposphere have increased by
36% since 1750.
d. The contribution of halocarbon gases to global warming is
lower now due to the Montreal Protocol of 1987.
e. Water vapor is the most abundant greenhouse gas, and its
concentration increases as tropospheric temperatures rise.
F. Aerosols may exert a cooling effect on the lower atmosphere.
1. Microscopic droplets and particles can have either a warming or a
cooling effect. Most tropospheric aerosols, such as the sulfate
aerosols produced by fossil fuel combustion, may slow global
warming in the short term.
G. Radiative forcing expresses change in energy input over time.
H. The atmosphere is not the only factor that influences climate.
1. Milankovitch cycles are changes in Earth’s rotation and orbit
around the sun, and they result in slight changes in the relative
amount of solar radiation reaching Earth’s surface at different
latitudes.
2. The sun varies in the amount of radiation it emits over short and
long time scales. This is referred to as solar output.
3. Ocean absorption.
a. The oceans absorb carbon dioxide directly from the
atmosphere through direct solubility of gas in water.
b. Marine phytoplankton also uptake carbon dioxide for
photosynthesis.
4. Oceanic circulation also shapes climate.
a. El Niño conditions occur when equatorial winds weaken and
allow warm water from the western Pacific to move eastward,
eventually preventing cold water from welling up in the
eastern Pacific.
b. In La Niña events, cold surface waters extend far westward in
the equatorial Pacific.
c. Many scientists today are exploring whether globally warming
air and sea temperatures may be increasing the frequency and
strength of El Niño events.
d. Ocean currents and climate also interact through the
thermohaline circulation, a worldwide current system in
which warmer, fresher water moves along the surface and
colder, saltier water moves deep benearh the surface.
e. North Atlantic Deep Water (NADW) is part of a circulation
pattern that moves warm surface water northward toward
Europe where cooler water then sinks and returns in the other
direction.
III. Studying Climate Change
A. Proxy indicators tell us about the past.
1. Ice caps and glaciers have preserved tiny bubbles of ancient
atmosphere.
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2. Sediment beds beneath bodies of water can be analyzed to learn
about the ancient vegetation in an area and, by extension, what the
climate was like at the time.
3. These sources of indirect evidence, which substitute for direct
measurements, are called proxy indicators.
4. Other proxy indicators include coral reefs and tree rings.
B. Direct atmospheric sampling tells us about the present.
1. Charles Keeling of the Scripps Institution of Oceanography
documented trends in atmospheric carbon dioxide concentrations
starting in 1958.
2. Keeling’s data show that atmospheric carbon dioxide
concentrations have increased from around 315 ppm to 383 ppm
since 1958.
C. Models help us understand climate change.
1. Coupled general circulation models (CGCMs) are computer
programs that combine what is known about weather patterns,
atmospheric circulation, atmosphere–ocean interactions, and
feedback mechanisms to simulate climate processes.
2. Over a dozen research labs around the world operate CGCMs.
3. Tests suggest that today’s computerized models provide a good
approximation of the relative effects of natural and anthropogenic
influences on global climate.
IV. Current and Future Impacts
1. Evidence that climate conditions have changed worldwide since
industrialization is now overwhelming and indisputable.
2. Climate change has already had effects on the physical properties
of the planet and if we continue to emit greenhouse gases, the
effects will be more severe.
A. The IPCC report summarizes evidence of climate change and predicts
future impacts.
1. The 2007 assessment of the IPCC summarized thousands of
scientific studies on climate change and documents observed
trends in surface temperature, rainfall patterns, snow and ice
cover, sea levels, storm intensity, and other factors.
2. The report included a series of possible climate change scenarios
and what strategies we might use to respond to these changes in
climate.
B. Temperature increases will continue.
1. The IPCC report concludes that average surface temperatures on
Earth increased by an estimated 0.74 °C (1.33 °F) in the century
from 1906 to 2005, with most of this increase occurring in the last
few decades.
2. Temperature increases are greatest in the arctic, causing glaciers
to shrink and disappear in the arctic and in many areas around the
world. Polar ice shelves are melting. This, combined with the
warming temperature resulting in expansion of the water, is
causing a rise in sea level.
3. Scientists are not yet sure, but recent analyses of storm data
suggest that warmer seas may not be increasing the number of
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storms, but likely are increasing the power of storms, and possibly
their duration.
Changes in precipitation vary by region.
1. Some areas will receive more rainfall and others will receive less.
2. Drought and floods are possible under these new conditions.
Melting ice and snow have far-reaching effects.
1. As the world warms, mountaintop glaciers disappear. Since 1980,
the World Glacier Monitoring Service estimates major glaciers
have lost an average of 9.6 m (31.5 ft) in vertical thickness. Many
glaciers on tropical mountaintops have disappeared already.
2. In the Arctic, as snow and ice melt, darker less-reflective surfaces
are exposed and Earth’s albedo, or capacity to reflect light,
decreases. More of the sun’s rays are absorbed at the surface and
the surface warms.
Rising sea levels will affect hundreds of millions of people.
1. As glaciers and ice sheets melt, increased runoff into the oceans
causes sea levels to rise.
2. Seas rose by an estimated 1.8 mm/year from 1961–2003 and 3.1
mm/year from 1993–2003.
3. Vertical rise in sea level of several inches can represent many feet
of horizontal incursion onto coastal lands.
4. Island nations are at great risk from events called storm surges,
caused by high tides and winds caused by storms.
5. If Greenland’s melting continues to accelerate, then sea levels
will.rise more quickly. Rising sea levels will force hundreds of
millions of people to choose between moving upland or investing
in costly protections against high tides and storm surges. Densely
populated regions on low-lying river deltas, such as Bangladesh,
will be most affected.
Climate change affects organisms and ecosystems.
1. Organisms are adapted to their environment and are affected when
the environment is altered.
2. Changes in timing of seasonal events such as temperaturedependent biological phenomena and the onset of spring are
creating complex effects in ecosystems worldwide.
3. There are spatial shifts in the ranges of organisms as many plants
and animals shift north to avoid hotter and drier conditions.
4. Species interactions will be affected.
Climate change exerts societal impacts.
1. Agriculture—cuts in agricultural productivity are possible as
droughts and floods increase. There could be a slight increase in
productivity as plants respond to higher carbon dioxide levels.
2. Forestry—insects, disease outbreaks, invasive species, and
catastrophic fires could all become more common.
3. Health—humans will experience more heat stress, tropical
diseases, respiratory ailments, hunger when droughts occur, and
compromised sanitation during flood events.
4. Economics—IPCC data suggest that global climate change will
cost nations between 1 to 5% of GDP.
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H. Impacts will vary regionally.
I. Are we responsible for climate change?
1. The IPCC reports that it is greater than 90% that the current global
climate change is caused by humans.
2. The scientific understanding of climate change is clear enough to
justify nations taking immediate action.
3. In the United States, a small group of “greenhouse skeptics” drove
the debate and prevented the nation from taking swift action.
These “skeptics” derived significant funding from corporate
entities in the oil, coal, and other extractive industries.
4. Recently, there has been a change in public polling data and
public perception such that even corporations are taking steps to
address climate change issues by asking governments to enact
legislation that would put caps on greenhouse gas emissions.
V. Responding to Climate Change
1. Today, there is a new broad consensus that climate change
presents great challenges to our society.
A. Shall we pursue mitigation or adaptation?
1. Mitigation would involve actions that would reduce emissions of
greenhouse gases.
2. Adaptation would involve acknowledging that climate change is
happening and that we must search for ways that will modify and
soften the blows. Adaptations can include building sea walls and
restricting coastal development.
3. Mitigation and adaptation are not mutually exclusive although
environmentalists charge that the adaptation approach is
sometimes “escapist.”
B. Electricity generation is the largest source of U.S. greenhouse gases.
C. Conservation and efficiency.
1. Conservation and efficiency can arise from new technologies, or
from individual ethical lifestyle choices.
2. Renewable sources of electricity can also reduce fossil fuel use.
D. Sources of electricity.
1. Natural gas has less impact on global warming than oil or coal.
2. Carbon sequestration or storage would allow current practices to
continue, provided carbon emissions are captured and stored.
E. Transportation is the second largest source of U.S. greenhouse gases.
1. One-third of the average American city is devoted to use by
cars—including roads, parking, garages, and gas stations.
2. The typical automobile is highly inefficient. Close to 85% of the
fuel you use does something other than move your car down the
road.
3. Automotive technology is making possible alternatives such as
electric vehicles, alternative fuels, hybrid vehicles, and hydrogen
fuel cells.
4. Driving less and using public transportation are lifestyle choices
that reduce reliance on cars.
F. Automotive technology.
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G.
H.
I.
J.
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L.
1. Government mandates, consumer demand, and higher fuel prices
will stimulate technology that will create fuel efficiency.
Driving less and public transportation.
1. Choosing where to live to reduce travel distance to work and
school will save energy.
2. Increasing public transportation options is the single most
effective strategy for conserving energy and reducing pollution.
We can reduce emissions in other ways.
1. Sustainable agriculture and land management that protects the
integrity of soil on cropland and rangeland enables soil to store
more carbon.
2. Reducing methane emissions from rice fields and cattle, and
reducing certain fertilizers are important techniques.
3. Preserving existing forests and increasing the rate of reforestation
will pull more carbon from the atmosphere.
4. Recovering methane from landfills and treating wastewater and
generating energy from solid waste incineration also reduce
emissions of global warming gases.
We will need to follow multiple strategies to reduce emissions.
Shall we use government mandates or market incentives?
1. At all levels, policymakers, industry, commerce, and citizens are
searching for ways to employ government AND markets to reduce
emissions in ways that are fair, economically palatable, effective,
and enforceable.
We began tackling climate change by international treaty.
1. In 1992, the United Nations convened the United Nations
Conference on Environment and Development Earth Summit in
Rio de Janeiro. Five documents were signed, including the U.N.
Framework Convention on Climate Change (FCCC), which
outlined a plan for reducing greenhouse gas emissions through a
voluntary, nation-by-nation approach.
a. In the U.S., greenhouse emissions increased by over 13% in
the 10 years following the Rio conference.
b. Germany and the United Kingdom both cut their greenhouse
gas emissions by 13% to 18% during the same period.
c. The decision was made to create a binding international treaty
that would require all signatory nations to reduce greenhouse
gas emissions. This is the Kyoto Protocol.
The Kyoto Protocol seeks to limit emissions.
1. The Kyoto Protocol was to take effect when nations responsible
for 55% of global greenhouse emissions ratified it. That occurred
in 2005 when Russia became the 127th nation to sign.
2. The United States, the world’s largest emitter of greenhouse
gases, refuses to ratify the protocol, claiming it is unfair to
industrialized nations.
3. Proponents of the Kyoto Protocol point out that the even with
compliance to the Kyoto Protocol, emissions would continue to
increase, but will not increase as quickly. All signatory nations are
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looking beyond Kyoto to the next negotiation that will supercede
Kyoto.
States are advancing climate change policy.
Market mechanics are being used to address climate change.
1. Programs such as cap and trade.
Carbon offsets are in vogue.
1. A carbon offset is 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.
2. In theory, carbon offsets are a good idea but they also fall short of
the goal in practice since there are not rigorous inspection and
enforcement actions.
You can reduce your own carbon footprint.
1. Collective action by global citizens is necessary to change future
outcomes of reducing our carbon footprint on the planet.
VI. Conclusion
A. Many factors, including human activities, can shape atmospheric
composition and global climate.
B. Scientists and policymakers are beginning to understand
anthropogenic climate change and its environmental impacts more
fully.
C. Reducing greenhouse gas emissions and taking other actions to
mitigate and adapt to climate change represents the foremost
challenge for our society in the coming years.
Key Terms
albedo
carbon offset
El Niño
global climate change
greenhouse effect
greenhouse gas
Intergovernmental Panel on
Climate Change (IPCC)
Kyoto Protocol
La Niña
Milankovitch cycle
proxy indicator
solar output
storm surge
thermohaline circulation
United Nations Framework
Convention on Climate Change
(FCCC)
Teaching Tips
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1. Provide students with detailed information about paleoclimate proxy data. The
National Oceanic and Atmospheric Administration (NOAA) Paleoclimatology
Program website (www.ngdc.noaa.gov/paleo/slides.html) provides detailed
information about paleoclimate proxy data. There are online slide sets with
photographs of field research, important data sets, and descriptive diagrams
appropriate for college-level courses. The available slide sets for
paleoclimatology are The Ice Ages, Climate and the Classic Maya
Civilization, Coral Paleoclimatology, Polar Ice Cores, Packrat Middens, Tree
Rings, Heinrich Events, and Low Latitude Ice Cores. A ninth set, Rock
Varnish, is available only as 35-mm slides at this time, but may be online in
the near future. Have groups of your students create either a poster or a
PowerPoint presentation about the above topics. You may want to include the
study of fossil pollen from core samples (paleopalynology—
www.geo.ucalgary.ca/~macrae/palynology is a good reference site). NOAA’s
website (www.ngdc.noaa.gov/paleo/ctl/glossary.html) provides an excellent
glossary of climate terms as well as an overview of a climate timeline.
2. In January 1998, a team of scientists from Russia, the United States, and
France retrieved a deep ice core near the Russian Vostok station in east
Antarctica. Preliminary data show that the ice core extends through four
climate cycles, with the oldest ice more than 400,000 years old.
Ask students to graph the carbon dioxide data from the ice core. The report
was published in Nature (Petit, J. R., et al., Nature v. 399 (6735), pp. 429–
436, 1999). The data can be downloaded from
www.ngdc.noaa.gov/paleo/icecore/antarctica/vostok/vostok.html.
Ask students the following questions:
•
Are climate cycles evident?
•
How did the temperature change with the carbon dioxide cycles?
•
Is the carbon dioxide concentration today higher or lower than those
recorded in the ice core?
3. Energy Star (www.energystar.gov) is a government-backed program helping
businesses and individuals to protect the environment through superior energy
efficiency.
There are home and business products in over 40 categories eligible for the
Energy Star designation. In general, these products use less energy, cost less
money to operate, and protect the environment. Ask students to choose a
product that they will likely buy over the next year. Assign them to search the
Energy Star website for the criteria required for that product, and ask them to
share that information with the rest of the class.
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4. Have your students learn more about how tree-ring research helps us to
understand ancient climates, fire ecology, activities and impacts of early
humans, global warming, and many other topics. The Laboratory of Tree-Ring
Research (www.ltrr.arizona.edu) has online lessons about tree-ring basics and
a tutorial called “Try Crossdating Yourself,” which teaches students how
scientists match and crossdate tree rings from many samples in both local and
wide-ranging areas to gather information about both small events (e.g., a local
insect infestation) and large ones (e.g., a severe drought). There are a series of
online exercises that can be printed out and used as homework or as lab
exercises. There are also numerous links to research publications and
subtopics such as dendroecology and dendroclimatology.
5. Ask students to examine statements from their power company, surveying
several months of data, if possible. Answer the following questions:

Is there a difference in the kilowatt hours used from one month to the
next?

If there is a difference, what are some reasons for the differences?

Ask students to predict which appliance, system, or activity in their homes
accounts for the most power use.

Invite a representative from a local utility to visit the classroom if that
utility offers a free home energy audit. Have the guest speaker explain the
benefits of a home energy audit and allow students to ask questions and
perhaps schedule an audit for their home or rental property.
6. A common frustration that instructors share is over how much material they
should present to their students for a particular course. When faced with a
wide range of possible topics, the temptation for instructors is to include as
many topics as possible, in as much depth as possible, which may result in a
low level of student understanding and retention, as demonstrated by low
exam grades.
Extensive research has investigated the way that people learn “chunks” of data
in a discipline, examining the differences between learning while a novice and
learning once a more expert status is attained, and how different types of
learners make the mental connections required to develop the broader
associations to form larger chunks of data. The research shows that it is
possible for most people to take in only somewhere between three and seven
new chunks of data at one time, with five usually being the optimal number.
The size of these chunks differs greatly, however, between novices and
experts. For example, a novice chunk might be a single new definition,
whereas an expert chunk could be an entire concept built around that already
well-understood definition plus three others.
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The take-home message for instructors is to first determine the amount of
information that forms a “chunk” for your students, and then to prepare a
lesson with about three to five of these chunks—certainly never more than
seven—in a single day, with some way to review those bits of information
before going on to the next lesson.
Additional Resources
Websites
1. Global Warming Site, Environmental Protection Agency (EPA)
(http://yosemite.epa.gov/OAR/globalwarming.nsf/content/index.html)
This website has national and international information about climate,
greenhouse emissions, potential impacts, actions, and links to other resources.
2. Global Warming, Earth Observatory, National Aeronautics and Space
Administration (NASA)
(http://earthobservatory.nasa.gov/Library/GlobalWarming/warming.html)
This NASA web reference site gives basic information about global warming,
summarizes the skeptics’ point of view, and describes NASA’s global climate
change projects.
3. NOAA-CIRES Climate Diagnostics Center, National Oceanic and
Atmospheric Administration (NOAA), Department of Commerce
(www.cdc.noaa.gov/ClimateInfo/tools.html)
This web resource provides a gateway to data and basic information about
climate and climate assessment.
4. Intergovernmental Panel on Climate Change, The United Nations
Environment Programme (UNEP) and World Meteorological Organization
(WMO) (www.ipcc.ch)
The official IPCC website has information about IPCC and its activities,
publications, press releases, and official documents.
5. Climate Prediction Center, The National Weather Service (NWS), NOAA,
Department of Commerce (www.cpc.ncep.noaa.gov)
This part of the National Weather Service website is dedicated to presenting
climate data, models, and statistical analyses to predict future climate trends.
Audiovisual Materials
1. Global Warming Series, distributed by The Video Project
(http://videoproject.com)
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This four-part series clearly illustrates exactly what global warming is, what
we are doing to cause it, and why it is dangerous.
2. Rising Waters: Global Warming and the Fate of the Pacific Islands, 2000,
produced by the Independent Television Service and Pacific Islanders in
Communications, distributed by Bullfrog Films (www.bullfrogfilms.com)
This video examines the problem of global climate change by showcasing the
personal stories of Pacific Islanders.
3. Turning Down the Heat, 1999, produced by Jim Hamm Productions and
distributed by Bullfrog Films (www.bullfrogfilms.com)
This film profiles innovative alternative energy projects such as solar energy
in Holland and biogas in Denmark and Vietnam.
4. Be Prepared for Global Warming, 2003, distributed by Films for the
Humanities & Sciences (www.films.com)
This program examines how land and populations made vulnerable by rapidly
rising worldwide temperatures are protected.
5. The Impact of Global Warming, 2000, distributed by Films for the Humanities
& Sciences (www.films.com)
This program travels the world to observe how global warming, accelerated
and exacerbated by air pollution, is affecting society.
6. An Inconvenient Truth: A Global Warning. (2006). 96 minutes PG. An
Academy Award–winning film by Vice President Al Gore. A compelling
view of the future of Planet Earth—and human civilization. Touted as a wakeup call that cuts through the myths and misconceptions to deliver the message
that global warming is a real and present danger, the film brings home Al
Gore’s message that we must act now to save the Earth. In end-of-term
surveys, after several terms of showing this film, students rate it as one of the
most important experiences they take away from the class. It is important to
allow time for students to decompress and debrief after viewing this film.
Weighing the Issues: Facts to Consider
Agriculture in a Warmer World
Facts to consider: Analysts are divided about whether the shift in agricultural
locations due to global climate change will raise or lower global agricultural
output. Since many countries in higher latitudes tend to be more developed
nations and are more equipped to operate agriculture at higher rates of
productivity, more food ought to be produced. On the other hand, much of the
arable land in wealthier countries may have already been developed for urban
areas, so some food-production potential may not be realized.
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If agriculture shifts northward, poorer nations may become even weaker
economically. These impoverished governments, already unable to provide
basic needs to their population, may become overwhelmed, heightening the
possibility of political unrest and war. Fighting may take place over essential
resources such as freshwater and useful agricultural land. The gap between
rich and poor nations may grow even wider as the mainly agrarian societies of
developing countries become subject to even harsher environmental
conditions for growing crops. It is also possible that such nations could make
positive adaptations, such as increasing use of water-conserving irrigation
techniques and cultivating crops that need less water. However, such change
requires massive amounts of funding, and may not happen due to a lack of
liquid capital. Finally, if current mid-latitude areas are less able to produce
food because of hostile environmental conditions, then northern lands, now
left wild, may become farms. Land use conflicts may also rise in the north
between environmental, developmental, and agricultural concerns.
Environmental Refugees
Facts to consider: Reponses will vary. Those who believe that climate change
is uncertain or part of a natural cycle would not be influenced by refugee flow,
and may posit that the rise in sea level is temporary, thus allowing refugees to
return to Tuvalu. It could be argued that Tuvalu islanders may have wanted to
become part of a more developed country such as New Zealand and are using
their refugee status to accomplish this goal at the expense of the host country.
A Tuvalu resident would tend to look at this issue in human, social, and
cultural-survival terms, stating that it is not fair that the actions of others are
having such a devastating effect on their island nation. A U.S. oil industry
executive, though sympathetic, might argue that far fewer people have been
disturbed than would be if fossil fuel use were curtailed to the point that
would be required to reverse global warming. The economic and social
dislocations caused by this shift would be on a more massive scale than what
has occurred in island nations.
To save their way of life, people in Tuvalu or the Maldives might try to build
seawalls, build homes on stilts, and construct other structures that will reduce
the damage caused by storm surges. They may develop tourist-oriented
markets to help expose people from developed countries to the value of their
island nation, thus making them aware of the threat that the island nation faces
and potentially making them advocates on the island’s behalf. They can take
steps toward restoring the coral reefs in order to compensate for the damage
being done by storm surges. They can build alliances with other island nations
and developed countries to gain international recognition and political clout.
Residents of coastal Florida could also build seawalls and structures to reduce
storm surge damage, and will likely be better able than the island nation
citizens to do so because of their greater wealth.
The Precautionary Principle
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Facts to consider: Most of the answers to these questions will require an
individual response. On a practical level, economics will have to play a
significant role in the discussion. Many of the most developed arguments
against applying the precautionary principle to the issue of global climate
change focus on the economic costs of decreasing or eliminating fossil fuel
use as well as on the social consequences that these economic costs could
bring. Those arguing for the precautionary principle could cite economic
factors that favor their approach, such as the economic benefits of maintaining
established agriculture wherever it exists, especially in developing countries.
Land and coastline loss, health impacts, human relocations, and other effects
of global climate change can also be cited for their negative economic
consequences. Interestingly, the Tragedy of the Commons can be applied to
both lines of argument, with the difference between the arguments being
whether the students feel that short- or long-term results are more important.
The Science behind the Stories: Thinking Like
a Scientist
Understanding El Niño and La Niña
Hypothesis: Increased global air and ocean surface water temperatures are
responsible for the increasing frequency of El Niño and La Niña events in the
Pacific Ocean.
Monitoring: Scientists analyzed data from a system of buoys that make up the
Tropical Atmosphere Ocean Project, also known as the TAO/TRITON. These
buoys are anchored across the Pacific Ocean along the equator and monitor
oceanic wind direction and surface water temperatures. Scientists use the data
to construct temperature and wind direction profiles of the equatorial Pacific
Ocean during normal and El Niño conditions.
Application: The profiles constructed by scientists are used to predict the
extent and severity of El Niño events. These predictions allow governments
and individuals to better prepare for extreme weather conditions and changes
in ocean conditions.
Implication: Analyses of the data from these buoys clearly show the
integration among the atmosphere, the oceans, and regional and global climate
by furthering our understanding of the connections among El Niño and La
Niña events, climate change, and their effects on other environmental systems.
Scientists Use Pollen to Study Past Climate
Observation: Climate in an area can be studied by examining the types of
vegetation that grow in the area. Past climates can be studied by examining
plant remains in sediment cores from freshwater lakes and ponds.
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Study: In the early 1990s, J. S. McLachlan of Harvard University and L. S.
Brubaker of the University of Washington studied the past climate of
Washington State’s Olympic Peninsula by examining plant remains in
sediment cores taken from a cedar swamp and a small freshwater lake. Cores
were taken from sample sites, wrapped in plastic and foil, and then frozen. A
1-mm-thick slice was cut from the core every 10 to 30 cm. The core slices
were analyzed for large plant material, pollen, and charcoal, with pollen being
the focus because of its resistance to biological decomposition and, because it
is easily transported by wind, the fact that it allows for plant species to be
identified over a large region. Macroscopic plant parts were identified and
used to characterize the flora and climate of local areas, and charcoal was used
to construct a history of forest fires. Using this correlation with regional
historical climate data from other sources, and from the fact that the deeper a
core is, the older the sediments are, a relative chronology could be determined.
Results: A general plant and climate history of the Olympic Peninsula was
constructed using plant species to determine whether warm, wet conditions
were present in the past, or whether cold-loving plants revealed a cooler
climate.
InvestigateIt Case Studies and Videos
Case Studies
As Weather Shifts,
Beaches May Pay a
Heavy Price
Eskimos Seek to Recast
Global Warming as a
Rights Issue
How Drought Just
Might Bring Water to
the Navajo
As the Seas Warm,
Algae Help Some Coral
Stand Up to the Heat
Antarctic Glaciers
Quicken Pace to Sea;
Warming Is Cited
Studies Find
Atmosphere Is Warmer
Japan Squeezes To Get
the Most Of Costly
Fuel
Earth Has Become
Brighter, but No One Is
Certain Why
At Australia’s Bunny
Fence, Variable
Cloudiness Prompts
Location
Topic
Florida
Oceans
Buenos Aires,
Argentina
Ethics
Navajo Nation, New
Mexico
Freshwater
Res.
Global Commons
Oceans
Alabama
Global
Warming
Global
Warming
Japan
Renewable
Energy
Switzerland
Air
Pollution
Australian Outback
Global
Warming
Antarctica
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Region
Australia
Climate Study
In Sweden, It's Global
Warming vs. Big Heavy
Cars
The Climate Divide:
Reports From Four
Fronts in the War on
Warming
The Climate Divide:
Reports From Four
Fronts in the War on
Warming
The Climate Divide:
Reports From Four
Fronts in the War on
Warming
The Climate Divide:
Reports From Four
Fronts in the War on
Warming
Trying to Connect the
Dinner Plate to Climate
Change
It's Maple Syrup Time,
So Why the Whiff of
French Fries?
Sweden
Global
Warming
Sweden
Blantyre, Malawi
Global
Warming
Malawi
Perth, Australia
Global
Warming
Australia
Dhanaur, India
Global
Warming
India
Maasbommel, The
Netherlands
Global
Warming
Netherlands
Illinois
Global
Warming
Illinois
Vermont
Glaciers in Retreat
India
A Team of 2, Following
the Scent of Polar Bears Canada
Russia's Strategy: Save
Polar Bears With Legal
Hunt
A Passion for Soccer
and the Environment
Balmy Weather May
Bench a Baseball
Staple
Videos
The Day After
Tomorrow
Ethanol Myths
Global
Warming
Global
Warming
Global
Warming
Vermont
India
Canada
Vankarem, Russia
Biodiversity
Russia
Colorado
Urbanization
Forestry,
Global
Warming
Topic
Global
Warming
Energy
Colorado
Pennsylvania
Location
New York, NY
United States
Pennsylvania
Region
Indiana
Answers to End-of-Chapter Questions
Testing Your Comprehension
1. Approximately 30% of incoming solar radiation is reflected back into space,
and the other 70% is absorbed by the atmosphere or Earth’s surface. Outgoing
heat radiation from the surface is absorbed by greenhouse gases in the lower
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atmosphere, and then reradiated, warming the air.
2. Although carbon dioxide has a lower global warming potential than some
other greenhouse gases, its abundance in the atmosphere gives it the most
influence over climate of all gases whose concentrations are being increased
by human activity. Water vapor is a greenhouse gas. Increased atmospheric
water vapor could increase atmospheric warming by absorbing more outgoing
infrared radiation, which would cause more evaporation and therefore more
atmospheric water vapor, creating a positive feedback loop. However, it could
also increase atmospheric reflectivity of incoming visible-wavelength solar
radiation, which would result in less solar energy penetrating the atmosphere
to warm the surface, thereby cooling the surface—a negative feedback effect.
3. The ancient atmosphere can be studied by extracting trapped air bubbles from
cores bored through layers of accumulated ice in the polar ice caps and ice
sheets.
4. Coupled general circulation models (CGCMs) have been effective aids in
climate prediction, and results from them form the basis for most of the
predictions in the influential IPCC assessment reports. Climate models work
by modeling the physics of the transfer of matter and energy in the oceanatmosphere system. Modelers use known observed data to set parameters that
enable the simulation and projection of future data.
5. Figure 18.12 lists many observed and predicted trends in climate and their
impacts. Among these, five observed (current or past) trends include: (1)
Earth’s average surface temperature has risen 0.74 °C (1.33 °F) in the past 100
years; (2) sea level rose by an average of 17 cm (7 in.) in the 20th century; (3)
ocean water became more acidic by about 0.1 pH unit in the past century; (4)
arctic areas have warmed the fastest of all regions; and (5) precipitation has
increased in a number of regions (e.g., e. North America, e. South America, n.
Europe, and n. and c. Asia), but has decreased in others (e.g., the Sahel, the
Mediterranean, s. Africa, and parts of s. Asia). Projected future trends include:
(1) Earth’s average surface temperature will rise 1.8–4.0 °C (3.2–7.2 °F) in the
21st century; (2) sea level will rise 18–59 cm (7–23 in.) in the 21st century;
(3) ocean water will decrease in pH by 0.14–0.35 units by century’s end; (4)
species ranges will continue to shift toward the poles and upward in elevation,
and the timing of seasonal phenomena such as migration and breeding will
continue to shift; and (5) the melting of mountain glaciers will reduce water
supplies to millions of people.
6. Rising sea levels can flood coastal areas, causing the loss of significant areas
of coastal wetlands and forests, salt intrusion into coastal aquifers, and
displacement of coastal inhabitants in the face of increased danger and
property damage from storm surges and flooding. Coastal ecosystems will be
affected in various ways by rising sea levels. Coral reef ecosystems will be
degraded or may disappear in many areas, due in part to storm surges, but
primarily because increasingly acidic water (from the absorption of
atmospheric carbon dioxide) will kill corals (and thereby threaten the diverse
array of organisms that depend on coral reefs).
7. Drought, flooding, and temperature extremes in some areas may threaten
agriculture, but longer growing seasons in other areas may increase
productivity. The IPCC predicts that temperate-zone crop yields will rise until
temperature warms beyond 3 °C (5.4 °F), but that in the dry tropics and
subtropics, crop productivity will fall and lead to hunger. Species of plants
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and animals (and entire forest communities) are already beginning to shift
toward the poles and upward in elevation. As for human health, the hazards of
heat stress, the spread of tropical diseases, flooding of sewage treatment
systems, injuries, and storm-related drowning should all increase under a
warmer global climate. There should, however, be fewer cold-climate-related
diseases and injuries. Researchers project that negative health impacts will
outweigh positive health impacts, but there is much uncertainty in this.
8. U.S. greenhouse gas emissions come primarily from the combustion of fossil
fuels to generate electricity and from the combustion of fossil fuels to power
transportation (cars, trucks, etc.). In both cases, the demand for the product
(electricity, mobility) is considerable, and growing. We can reduce emissions
in each case by reducing demand, increasing efficiency, and substituting
alternative technologies that release fewer greenhouse gases.
9. International treaties set goals and introduce a level of accountability for
nation-states. They may also exert some political or economic pressure to
persuade countries to achieve those goals. The U.N. Framework Convention
on Climate Change (1992) and the Kyoto Protocol (1997) are two examples of
attempts to reduce greenhouse gas emissions.
10. Emissions trading systems (also referred to as permit-trading or cap-and-trade
systems) are a major market-based approach for reducing greenhouse gas
emissions. In these systems, governments set limits on overall emissions
levels; issue permits to emit to companies, corporations, and utilities; and let
the emitting parties buy, sell, and trade permits among themselves. Emissions
trading systems may work well because the private sector can often achieve
goals in an efficient manner with fewer costs. They may not work well if they
allow hotspots of pollution or if government fails to design the system in a
way that gives polluters adequate incentives to reduce pollution. Another way
in which the free market is used to reduce emissions is through carbon
offsetting, in which one party pays another to reduce greenhouse emissions.
This approach can be efficient and appealing, but will work only if there is
oversight and enforcement that guarantees that the offset funds achieve what
they aim to achieve.
Interpreting Graphs and Data
1. The approximate percent changes in CO2 emissions from transportation,
electricity generation, and residential, commercial, and industrial primary
energy use between 1980 and 2006 are 36%, 53%, –8%, –13%, and –20%,
respectively. Each is calculated using the formula: % change = ( ((2006
emissions/1980 emissions) –1) × 100).
2. Between 1980 and 2006, CO2 emissions per capita decreased in all sectors
except electricity generation and transportation. Similarly, CO2 emissions per
unit of total economic activity decreased in all sectors over that time period.
3. Since transportation and electricity generation are the biggest producers of
CO2 emissions and have shown the least improvement in efficiency, they are
arguably the sectors where the greatest gains can still be made. Increased
CAFE (automotive fuel efficiency) standards would be one effective strategy
to spur efficiency in transportation. Support of low-emissions technologies
and approaches for power generation (such as using power sources less
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carbon-intensive than coal), would be an effective course of action to take for
electricity generation.
Calculating Ecological Footprints
Person
Carbon footprint
(kg per person per year)
4,000
11,000
19,000
Answers will vary
2,000
World average
Average for industrialized nations
U.S. average
Your footprint
Average needed to halt climate
change
Your footprint with three changes
Answers will vary
[NOTE: Figures in the table are current as of August 2007, and may vary
subsequently. Questions should be addressed using values given by the
footprint calculator at the time the quiz is taken, and not to the potentially
outdated values shown here.]
1. Answers will vary. Students may have larger or smaller footprints than the
average U.S. resident, but most will have substantially larger footprints than
the average person in the world. The consumption-intensive North American
lifestyle accounts for this, particularly our auto transportation, electrical use,
air travel, and industrialized agriculture.
2. Answers will vary. Changes in choice of a place to live and auto and jet travel
will make relatively large differences.
3. Answers will vary, but achieving complete carbon neutrality will be very
difficult. Purchasing carbon offsets will likely be necessary for most people.
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