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C. L. Andrews/National Geographic Stock

Global Atmospheric

Changes

MELTING ICE AND RISING SEA LEVELS

P

owerful evidence that Earth is warming comes from the melting

of continental and polar ice. Globally, the mean thickness of

glacial ice diminished by 14 m (46 ft) from 1955 to 2005 (see graph).

In 2002, an iceberg roughly twice the size of Rhode Island broke off

from the Antarctic Peninsula. The Antarctic ice pack has retreated and

thinned, losing 40 percent of its volume since 1980.

The Muir Glacier in Alaska was once enormous, with a huge

vertical front from which icebergs calved into Glacier Bay. Today,

the Muir Glacier has shrunk to a fraction of its former size (see

photograph, taken in 2004; the inset shows approximately the same

location in 1903).

Human-caused climate change is an established phenomenon.

Within the scientific community, the question is no longer whether

climate change will occur. Rather, we are concerned about how

and whether we can reduce the rate of changes that have already

begun, and prepare for those changes we cannot avoid. The

biggest culprit in climate change is an increase in atmospheric

carbon dioxide (CO 2 ), which is generated primarily through the

burning of fossil fuels.

In this chapter we examine the challenges of global

atmospheric changes: climate change, ozone depletion, and

acid deposition. Changes in economics, politics, energy use,

agriculture, and human behavior will be necessary to address

these issues.

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