Visualizing Environmental Science

Global Climate Change 229

Reducing energy use (for example, by driving less)

and increasing efficiency (for example, by switching to

hybrid cars) will reduce our output of CO 2 , and will help

mitigate global climate change. Energy-pricing strategies,

such as carbon taxes and the elimination of energy subsi-

dies, are other policies that could mitigate global climate

change. Most experts think that using current technolo-

gies and developing such policies could significantly re-

duce greenhouse gas emissions with little cost to society.

Planting and maintaining forests also mitigates global

climate change. Like other green plants, trees remove car-

bon dioxide from the air and incorporate the carbon into

organic matter through photosynthesis. Reasonable esti-

mates suggest that trees could remove 10 to 15 percent of

the excess CO 2 in the atmosphere, but only through enor-

mous plantings, so such efforts should not be considered a

substitute for cutting emissions of greenhouse gases.

Many countries are investigat-

ing carbon management. Several

experimental power plants cur-

rently capture CO 2 from their flue

gases, but the technology is new

(ˆ}ÕÀiÊ ™°£{). Technological

innovations that more efficiently

trap CO 2 from smokestacks would

help mitigate global climate change and allow us to con-

tinue using fossil fuels (while they last) for energy. The

carbon could be sequestered in geologic formations or

in depleted oil or natural gas wells on land.

Additional strategies to mitigate climate change

include the following:

sPlanting trees on degraded land

sIncreasing efficiency of coal-fired power plants

sReplacing coal-fired power plants with nuclear

power, hydropower, wind power, or even natural gas

sIncreasing fuel economy of motor vehicles

sRedesigning cities to reduce reliance on single-

occupant vehicles

sInsulating buildings to reduce the need for heating

in the winter and cooling in the summer

sImproving management of agricultural soils

Adaptation to Global Climate Change Because

the overwhelming majority of climate experts think

human-induced global climate change will continue,

government planners and social scientists are developing

Dealing with Global Climate Change:
Mitigation and Adaptation

There are basically two ways to manage global c limate
change: mitigation and adaptation. Mitigation is the
moderation or postponement of global climate change
through measures that reduce greenhouse gas emissions.
Adaptation is a planned response to changes caused by
global climate change. Because the impacts of climate
change have already begun, some combination of mitiga-
tion and adaptation is necessary to avoid severe or disrup-
tive effects. The earlier we begin implementing strategies
for mitigation and adaptation, the more effective they
are likely to be.
We will have to deal with all greenhouse gases as we
develop strategies to address global climate change, but
we focus on CO 2 because it is produced in the greatest
quantity and has the largest total effect. Carbon dioxide
has an atmospheric lifetime of more than a century, so
emissions produced today will still be around in the 22nd
century. The extent and severity of global climate change
will depend on the amount of additional greenhouse gas
emissions we add to the atmosphere.
The rate of increase of atmospheric greenhouse gases
from fossil fuels depends on such factors as economic con-
ditions, policy choices, population growth, and technology
changes. To accommodate uncertainty about these factors,
climate scientists consider several scenarios, or possible fu-
tures. One such scenario, which assumes no intentional re-
duction in emissions, predicts that greenhouse gases will be
at least triple the preindustrial concentration by 2100. Even
in the most optimistic scenario, greenhouse gases in 2100
will probably be at least 550 ppm, or roughly twice the pre-
industrial concentration. Other uncertainties include how
quickly the ocean can absorb heat and carbon dioxide, and
how cloud cover will change. For these and other reasons,
scientists are uncertain about how much change will occur
during the next 90 years, but highly certain that tempera-
ture, precipitation, and sea level will continue to change
significantly, with dramatic effects on life on Earth.

Mitigation of Global Climate Change Because
most of the CO 2 that human activities produce comes
from burning coal, oil, and natural gas, climate change
is essentially an energy issue. Developing alternatives to
fossil fuels offers a solution to warming caused by CO 2
emissions. We address alternatives to fossil fuels, in-
cluding solar, hydroelectric, wind, and nuclear power,
in Chapters 17 and 18.

carbon

management

Ways to separate

and capture the CO 2

produced during the

combustion of fossil

fuels and then se-

quester (store) it.