BIO320 CHAPTER 17

17-1
ENVIRONMENTAL
SCIENCE
A Study of Interrelationships
15th Edition
Climate Change: A 21st Century Issue
Chapter 17
©2019 McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction
or further distribution permitted without the prior written consent of McGraw-Hill Education.

© 2019 McGraw-Hill Education.
17-2
Chapter Outline (1 of 2)
17.1 Earth Is a Greenhouse Planet
17.2 Geologic Evidence of Climate Change
17.3 Growth in Knowledge of Global Warming and Climate
Change

17-3
Chapter Outline (2 of 2)
17.4 Sources and Impacts of Principal Greenhouse
Gases
17.5 The Current State of Knowledge about Climate
Change
17.6 Consequences of Climate Change
17.7 Addressing Climate Change
Source: Bruce F. Molnia, U.S. Geological Survey

17-4
17.1 Earth Is a Greenhouse
Planet (1 of 4)
The Earth is unique among the planets in having a
temperature that allows for water to exist in a liquid form.
All living things are primarily made up of water.
• The human body is over 50 percent water.
• All early forms of life developed in the oceans.
• The presence of liquid water is essential for life as we know it.

17-5
Planet (2 of 4)
The Earth’s temperature is determined by several factors:
• Earth’s distance from the sun
• Changes in the energy output of the sun
• The presence of carbon dioxide in the atmosphere.
• Although Earth’s orbit around the sun results in small changes in the
distance between the Earth and sun and the sun’s energy changes
slightly on about an 11 year cycle, these differences appear to have little
effect on Earth’s temperature.

17-6
Planet (3 of 4)
Several gases in the atmosphere are transparent to
ultraviolet and visible light but absorb infrared radiation.
These gases allow sunlight to penetrate the atmosphere
and be absorbed by the Earth’s surface.
• This sunlight energy is reradiated as infrared radiation (heat), which
is absorbed by the greenhouse gases in the atmosphere.
• Because the effect is similar to what happens in a greenhouse, these
gases are called greenhouse gases, and the warming that occurs
because of their presence is called the greenhouse effect

17-7
Planet (4 of 4)
Carbon dioxide is a greenhouse gas.
Although the amount of carbon dioxide in the atmosphere is
small, its effect is significant.
• According to NASA if there were no carbon dioxide in the
atmosphere Earth’s temperature would be about -18oC (0oF) instead
of the current temperature of about 15oC (60oF).
• Thus the greenhouse effect caused by the presence of carbon
dioxide in the atmosphere makes Earth suitable for life.

17-8
Greenhouse Effect
Source: Data from Climate Change-State of knowledge. October 1997. Office of Science and Technology Policy, Washington, D.C.

17-9
17.2 Geologic Evidence of
Climate Change (1 of 2)
Although the phrases global warming and climate change
are sometimes used interchangeably, they are really
different aspects of the same problem.
Global warming relates to an average increase in
temperature of the Earth’s atmosphere
Climate change refers to the many other changes that
come about because of global warming.

17-10
17.2 Geologic Evidence of
Climate Change (2 of 2)
Geologic studies of Earth’s history gave clues that climate
had changed significantly over time.
Some geologic periods were hotter than today and some
were colder.
• Evidence of continental glaciers that covered large portions of North
America, Europe, and Asia brought about a recognition that climate
change had happened in the recent geologic past.

17-11
Continental Glaciers

17-12
Changes in Average Global
Temperature
Source: Data from NOAA Climate.gov. (January 2017.)

17-13
17.3 Growth in Knowledge of Global
Warming and Climate Change (1 of 3)
The average temperature of the Earth has been increasing
since1980s.
Scientists initially tried to determine if the warming was a
natural phenomenon or the result of human activity.
• Evidence of past climate change going back as far as 160,000 years
indicates a close correlation between the concentration of
greenhouse gases in the atmosphere and global temperatures.

17-14
Computer models are not the only evidence of the causes
and effects of climate change:
• Records of the amount of carbon dioxide in the atmosphere that
show steady increase in the amount of carbon dioxide
• Studies of gas bubbles trapped in glaciers that indicate what the
atmosphere was like before the time of the industrial revolution that
began in the mid1700s
• Satellite photos that show how snow and ice conditions change
• Migration behavior of terrestrial and marine animals that show
changes in the time of migration or the route followed
• Ocean studies of CO2 content, pH change, and other changes in
chemistry

17-15
Evidence of climate change (continued):
• Changes in growing seasons
• Physical measurements of the retreat of glaciers and thickness of ice
sheets
• Effects of increased carbon dioxide on photosynthesis
• Wind patterns
• Ocean currents
• Effects of particulates from natural (wind erosion, volcanos) and
human activities on climate
• Sea level measurements
• Frequency and strength of tropical storms

17-16
Research Related to Climate
Change

17-17
Changes in Atmospheric Carbon
Dioxide

17-18
Changes is Atmospheric Methane

17-19
The most important greenhouse gases are:
• Carbon dioxide (CO2),
• Methane (CH4)
• Chlorofluorocarbons (primarily CCl3F and CCl2F2)
• Nitrous oxide (N2O).
17.4 Sources and Impacts of Principal
Greenhouse Gases (1 of 7)

17-20
Carbon dioxide (CO2) is the most abundant of the
greenhouse gases and is responsible for about 65 percent
of global warming.
• It occurs as a natural consequence of respiration and fermentation by
organisms.
• However, much larger quantities are put into the atmosphere as a waste
product of energy production.
• Another factor contributing to the increase in the concentration of carbon
dioxide in the atmosphere is deforestation.

17-21
Measurement of carbon dioxide levels at the Mauna Loa
Observatory in Hawaii shows that the carbon dioxide level
increased from about 317 parts per million (ppm) in 1960 to
about 404 ppm in 2016.
• This is an increase of about 27 percent.
• It is generally accepted that the amount of carbon dioxide in the
atmosphere prior to the industrial revolution was about 280 ppm.
• The current concentration represents an increase of 45 percent over
preindustrial concentrations.

17-22
Methane (CH4) is the second most abundant greenhouse
gas and is responsible for about 17 percent of global
warming. It comes from biological sources and as a
byproduct of fossil-fuel use.
• Several kinds of microorganisms that are particularly abundant in
wetlands and rice paddies release methane into the atmosphere.
• Natural gas is primarily methane and oil and coal, contain some
methane as well.
• Currently the amount of methane in the atmosphere continues to grow.
Preindustrial concentrations were about 700 parts per billion (ppb).
Current concentrations are about 1,850 ppb.

17-23
Nitrous oxide (N2O), a minor component of the greenhouse
gas picture, enters the atmosphere primarily through the
use of fertilizers and fossil fuels.
• Nitrogen-containing fertilizers and animal manure used to improve
agricultural production contain nitrogen compounds.
• Certain soil bacteria convert these compounds to nitrous oxide.

17-24
Chlorofluorocarbons (CFCs) are also a minor component
of the greenhouse gas picture and are synthetic compounds
produced for particular uses.
• There are no natural sources of CFCs.
• CFCs were widely used as refrigerant gases in refrigerators and air
conditioners, as cleaning solvents, as propellants in aerosol
containers, and as expanders in foam products.

17-25
Although they are present in the atmosphere in minute
quantities, they are extremely efficient as greenhouse gases
(about 15,000 times more efficient at retarding heat loss
than is carbon dioxide).
• Because chlorofluorocarbons are a major cause of ozone
destruction, production and use of chlorofluorocarbons has been
sharply reduced and scheduled to be eliminated by 2020.

17-26
17.5 The Current State of Knowledge
about Climate Change (1 of 7)
In 1988, the United Nations Environment Programme and
the World Meteorological Organization established the
Intergovernmental Panel on Climate Change (IPCC) to
study the issue and make recommendations.
• A main activity of the IPCC is to provide an assessment of the state
of knowledge about climate change at regular intervals.

17-27
The IPCC is organized into several working groups:
• Working Group I deals with the physical science that relates to
climate change.
• Working Group II deals with the impacts of climate change.
• Working Group III deals with how to mitigate the effects of climate
change.

17-28
Working Group I published its portion of the Fifth
Assessment Report, Climate Change 2013: The Physical
Science Basis, in September of 2013.
• Two hundred and fifty-nine scientists from around the world were
involved in writing portions of the report.
• Over 600 people contributed material for the report.

17-29
Their report restated several important conclusions from
previous reports and added several new observations:
1. Human activity is clearly influencing climate.
2. Increased concentrations of greenhouse gases, particularly carbon
dioxide, are causing an increase in temperature.
3. Evidence of increased temperature is clear.

17-30
Fifth Assessment Report findings (continued):
3. Evidence of increased temperature is clear.
• The average temperature of the Earth has increased 0.65-1.06°C (1.2-
1.9°F) since 1880.
• Amounts of spring snow and ice have decreased in the northern
hemisphere. Snow is melting earlier in the year.
• The number of cold days has decreased and the number of warm days
has increased.
• The arctic region is warming more than the rest of the world.
• Permafrost (permanently frozen soil) temperatures have increased 2 to
3oC (3.6-5.4oF) and the thickness of the permafrost layer and the area of
the world that has a permafrost layer have decreased.

17-31
• There has been a reduction in the area covered by arctic sea ice at the end
of the summer season (September).
• Greenland and Antarctic ice sheets have been losing mass
• Glaciers are melting
• The arrival of spring is earlier in many parts of the world.

17-32
4. Increased carbon dioxide in the atmosphere and increased
temperature are affecting oceans.
• About 28 percent of carbon dioxide emissions end up in the ocean.
• Increased CO2 dissolved in water has decreased pH by 0.1pH unit. (A
26 percent increase in hydrogen ion concentration.)
• About 90 percent of the additional energy added to the Earth has been
stored in the oceans resulting in an increase of about 0.44oC (0.8oF) in
the temperature of the upper 75 meters of the oceans in the last 40
years.
• Sea level has risen about 19 cm (7.5 in.) between 1901 and 2010.
• The rate of sea level rise has been increasing and was about
3.2mm/year (0.125 inches/year) from 1993 to 2010.

17-33
17.6 Consequences of Climate
Change (1 of 2)
A small increase in the average temperature of the Earth
may seem trivial, however, such an increase could set in
motion changes that could significantly alter the climate of
major regions of the world.
• Computer models suggest that rising temperature will lead to
changes to the hydrologic cycle, sea level, human health, the survival
and distribution of organisms, and the use of natural resources by
people.
• Furthermore, some natural ecosystems or human settlements will be able
to withstand or adapt to the changes, while others will not.

17-34
17.6 Consequences of Climate
Change (2 of 2)
Poorer nations are generally more vulnerable to the
consequences of global warming.
• These nations tend to be more dependent on economic activity that
is climate-sensitive, such as subsistence agriculture, and lack the
economic resources to adjust to the changes that global warming
may bring.
• The Intergovernmental Panel on Climate Change has identified Africa as
“the continent most vulnerable to the impacts of projected changes
because widespread poverty limits adaptation capabilities.”

17-35
Disruption of the Hydrologic Cycle
(1 of 4)
In a fundamental way the hydrologic cycle (evaporation,
precipitation, water flow, groundwater, etc.) is driven by
energy.
• The primary source of energy is the temperature of the Earth, which
is determined by the input of energy from the sun and the heat-
trapping effect of greenhouse gases.
• Thus, a change in the Earth’s temperature is expected to change
weather and climate.

17-36
(2 of 4)
Weather includes short-term activities such as; temperature
changes, rain and snow events, winds, clouds, and other
factors.
Climate is the long term average of weather patterns.
• Thus, if climate is changing we should expect changes in weather
patterns also.

17-37
(3 of 4)
Higher temperatures result in increased evaporation, which
will cause some areas to become drier, while the increased
moisture in the atmosphere will result in greater rainfall in
other areas.
Snowfall patterns are also expected to change with some
areas receiving more snow and others less.

17-38
(4 of 4)
Recent data suggest that:
• The amount of spring snow has decreased
• Snow is melting earlier in the year
• Hurricanes are more powerful
• There are more hot days and fewer cold days
• Spring is arriving earlier

17-39
Rising Sea Level (1 of 2)
A warmer Earth will result in rising sea levels for two
different reasons:
• When water increases in temperature, it expands and takes up more
space.
• In addition, higher temperatures are causing the melting of glaciers,
which adds more water to the oceans.
• Rising sea level erodes beaches and coastal wetland, inundates low-lying
areas, and increases the vulnerability of coastal areas to flooding from
storm surges and intense rainfall.

17-40
Rising Sea Level (2 of 2)
By 2100, the IPCC projects sea level to rise by 26 to 98
centimeters (10-39 inches).
• A 50-centimeter (20-inch) sea-level rise will result in substantial loss
of coastal land in North America, especially along the southern
Atlantic and Gulf coasts, which are subsiding and are particularly
vulnerable.
• Many coastal cities would be significantly affected by an increase in
sea level.
• World-wide about 600 million people live in low-lying coastal areas.
• The land area of some island nations and countries such as Bangladesh
would change dramatically as flooding occurred.

17-41
Hurricane Matthew
Source: USGS

17-42
Health Effects
The most direct effect of climate change is the impact of
hotter temperatures.
• Extremely hot temperatures increase the number of people who die
(of various causes) on a given day.
• For example, people with heart problems are vulnerable because the
cardiovascular system must work harder to keep the body cool during
hot weather.

17-43
Heat Affects Health
In 2010, a record-breaking heat wave in Russia resulted in
62 consecutive days of above normal temperatures, and in
Moscow.
• About 11,000 deaths were attributed to the heat.
In June 2013, a heat wave in the U.S. Southwest resulted in
several record temperatures and several deaths.
• Even though the temperatures in the U.S. Southwest were higher
than those in Russia, the number of U.S. deaths was much lower
because most U.S. buildings have air conditioning and most Russian
buildings do not.

17-44
Heat Affects Air Pollution
Climate change will also make air pollution problems worse.
• Higher air temperature increases the concentration of ozone at
ground level, which leads to injury of lung tissue and increases the
incidence of respiratory disease, asthma, and allergies.
• Because children and the elderly are the most vulnerable, they are likely
to suffer disproportionately from both warmer temperatures and poorer air
quality.

17-45
Tropical Diseases Could Migrate to
Former Temperate Regions (1 of 2)
The prevalence of particular diseases depends largely on
local climate.
• Several serious diseases appear only in warm areas.
• As the Earth becomes warmer, some of these tropical diseases may
be able to spread to parts of the world where they do not currently
occur.

17-46
Tropical Diseases Could Migrate to
Former Temperate Regions (2 of 2)
Diseases that are spread by mosquitoes and other insects
could become more prevalent.
• Such “vector-borne” diseases include malaria, dengue fever, yellow
fever, and encephalitis.
Some scientists believe that algal blooms could occur more
frequently as temperatures rise.

17-47
Changes to Ecosystems

17-48
Challenges to Agriculture and the
Food Supply
Climate strongly affects crop yields.
• Yields will fall in regions where drought and heat stress will increase.
• In regions that will receive increased rainfall and warming
temperatures yields should increase.
• However, episodes of severe weather will cause crop damage that will
affect yields.
• A warmer climate would reduce flexibility in crop distribution and increase
irrigation demands.
• Expansion of the geographic ranges of insect pests could also increase
vulnerability and result in greater use of pesticides

17-49
17.7 Addressing Climate Change
Improving energy efficiency has the double impact of
reducing carbon dioxide release and conserving the
shrinking supplies of energy resources.
• It makes sense to increase energy efficiency even if global warming
is not a concern.

17-50
Energy Efficiency and Green
Energy (1 of 3)
One way to stimulate a move toward greater efficiency
would be to place a tax on the amount of carbon individuals
and corporations release into the atmosphere.
• This would increase the cost of fuels and stimulate a demand for fuel
efficient products because the cost of fuel would rise.
• It would also stimulate the development of alternative fuels with a
lower carbon content and generate funds for research in many
aspects of fuel efficiency and alternative fuel technologies.

17-51
Energy (2 of 3)
Increases in energy efficiency and reductions in greenhouse
gas emissions are likely to have important related benefits
that could offset the costs.
• Greater energy efficiency would lead to reduced air pollution, which
would result in lower health care costs and time lost from work.
• A study of air pollution in China determined that there were 1.6 million
premature deaths in China in 2015.

17-52
Energy (3 of 3)
Green sources of energy such as wind, solar, and
hydroelectric, as well as nuclear power do not release
carbon dioxide.
• Switching to green sources of energy is the most effective way to
reduce carbon dioxide emissions.

17-53
Forests Store Carbon

17-54
The Role of Biomass (1 of 3)
Since carbon is an important component of living things,
what happens to biomass has a role to play in determining
atmospheric carbon dioxide.
• Forests consist of many long-lived tree species that can tie up carbon
for centuries

17-55
Preserving forests slows the rate of increase of atmospheric
carbon dioxide.
• This is particularly true for tropical forests since they are the last
remaining major unmodified forested areas in the world and they are
very efficient at capturing carbon dioxide.
• The burning of tropical rainforests to provide farm or grazing land
• Adds carbon dioxide to the atmosphere
• Reduces the rainforests’ ability to remove carbon dioxide from the
atmosphere
• A commonly cited estimate is that 20 percent of the additional carbon
dioxide entering the atmosphere is due to deforestation.

17-56
Planting trees has also been supported as a way to reduce
atmospheric carbon dioxide.
• Critics argue that this approach will provide only a short-term benefit.
• Eventually, the trees will mature and die, and their decay will release
carbon dioxide into the atmosphere at some later time.

17-57
Technological Approaches (1 of 4)
The U.S. Department of Energy has concluded that, relying
primarily on already proven technology, the United States
could reduce its carbon emissions by almost 400 million
metric tons.
• This is enough to stabilize U.S. emissions at 1990 levels.

17-58
Many different kinds of technological approaches have been
suggested as ways to limit the amount of carbon dioxide
added to the atmosphere:
• Alternative energy sources like wind, solar, hydroelectric, geothermal,
and nuclear power do not release carbon dioxide and can replace
current fossil-fuel energy sources.
• However, since fossil fuels currently provide nearly 90 percent of the
world’s energy, converting to a greater reliance on nonfossil-fuel energy
sources will require a great deal of new construction and technological
improvements.

17-59
Another approach to the carbon dioxide problem is to
prevent it from being released into the atmosphere.
• Carbon dioxide can be reacted with other compounds to produce
solid carbonate minerals (limestone is calcium carbonate) that could
be stored in landfills and prevent the release of carbon dioxide gas.
• It is also possible to capture and store carbon dioxide underground,
particularly in saline groundwater deposits and exhausted oil and gas
production wells.

17-60
However, all of these technological changes come with a
cost that will be reflected in the price of energy to the
consumer.
• Thus, as long as fossil-fuel sources of energy are less expensive
than non-fossil-fuel alternatives and removing carbon dioxide adds
significantly to the cost of energy, there will need to be government
policies that stimulate the deployment of these technologies.

17-61
International Agreements (1 of 5)
The phasing out of CFCs required significant technological
changes, but the changes were very rapid once a broad
international consensus was reached and a plan
established.
• Recent data show that CFCs in the atmosphere have begun to
decline.
• Although CFCs are a minor player in the climate change scenario,
the changes made to protect the ozone layer have had the side
benefit of reducing the release of a potent greenhouse gas.

17-62
1997 Kyoto Protocol
• A first step toward a worldwide approach to alleviating the problem.
Most countries of the world ratified the treaty.
• Although the United States did not officially ratify the treaty, it has been
an active participant in the series of climate change conferences held in
recent years.

17-63
Under the Kyoto Protocol only the economically developed
countries of the world were required to limit their
greenhouse gas emissions to a specific percentage below
1990 levels.
• They were to meet their targets by 2012.
• Economically developing countries including nearly all of Latin
America, Africa, and Asia did not have binding targets to meet.

17-64
In 2006 China became the world’s largest emitter of carbon
dioxide and the United States was in second place.
However, Americans still cause more pollution per person
than any other nation.
The European countries have been most successful in
reducing their greenhouse gas emissions.
Many of the heavily industrialized countries are actively
promoting changes that reduce greenhouse gas emissions.
In 2017 President Trump withdrew the United States from
the Paris Agreement. All but 3 countries remain in the
agreement.

17-65
Other heavily industrialized countries are meeting their
goals because of the major economic downturn in many
European countries.
• When the economy is bad, energy use declines and carbon dioxide
emissions fall.
The Kyoto Protocol expired in 2012 and at a meeting Doha,
Qatar in December 2012 an agreement was reached to
extend the Protocol through 2020.
• While Europe in general met its goal for greenhouse gas emissions,
most developing countries did not have goals to meet and
greenhouse gas emissions have continued to increase.

17-66
Summary (1 of 3)
The concept of climate change is not new.
Geological studies have demonstrated that climates have
change greatly over the Earth’s history.
Today’s climate change is different in that it is highly likely
that it is being caused by human activities.
The primary greenhouse gases are carbon dioxide, nitrous
oxide, methane, and chlorofluorocarbons.
These gases are strongly linked to an increase in the
average temperature of the Earth and, consequently, are
leading to major changes in the climate.

17-67
Summary (2 of 3)
These include warming of the Earth, particularly near the
poles.
The warming will result in melting of the permafrost,
glaciers, and sea ice; changes in rain and snowfall patterns;
shifts in the distribution of plants and animals; more intense
heat waves and severe storms; a rise in sea level; and
acidification of the oceans.
Other likely effects of climate change are health effects in
humans, extinction of some plants and animals, flooding of
cities, and changes in agricultural productivity.

17-68
Summary (3 of 3)
The primary factor involved in climate change appears to be
the carbon dioxide released from the burning of fossil fuels.
Since fossil fuel use is closely tied to economic
development, many developing countries are unwilling to
accept limits to their use of fossil fuels.

BIO320 CHAPTER 17

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