done by Dr. Syukuro Manabe, an atmospheric scientist at the National Oceanic
and Atmospheric Administration Geophysical Fluid Dynamics Laboratory in
Princeton, N.J., led him to testify before a congressional committee in 1985
that "winters in Siberia and Canada will be less severe. Because of the
penetration of warm, moisture-rich air into the high latitudes, a doubling of
atmospheric carbon dioxide or the equivalent might increase the rate of river
runoff in northern Canada and Siberia by 20 to 40 percent. Our climate model
also indicates that in response to the increased greenhouse gases, summer
drought will become more frequent over the middle continental regions of North
America and the Eurasian continent. For example, the model-produced summer
drought is characterized by dry soil, reduced cloud cover and higher surface
temperature, which resemble the situation during the dust bowl of the
A study by the
National Academy of Sciences suggests that water volume in northern California
rivers and in the Colorado River will decline by as much as 60%. This would
leave much of the West without water. Southern California would run dry and be
subjected to an increased incidence of fire, as would forests throughout much
of the West and upper Midwest.
Within the past
100 years, tide gauges on the Atlantic Coast of the U.S. have documented a
30-centimeter, or one-foot, rise in sea level. Globally, the average is about
five inches. Models predict that the level will have risen by another foot in
low-lying coastal regions of the U.S. in 2030, and by as much as three feet in
2100. According to Dr. Steven P. Leatherman, director of the Laboratory for
Coastal Research at the University of Maryland, at least part of the present
sea-level rise on the East Coast is caused by the natural compacting and
subsidence of coastal sediment. But at least 4.5 inches of the rise has been
caused by the expansion of warmer ocean surface waters and the melting of
mountain glaciers, triggered in part by the 0.5�C increase in global
temperature registered during the last century.
rise will promote increased coastal erosion," Leatherman says. "Already
approximately 80 percent of our sandy coastlines is eroding.... Artificial
nourishment is being used to restore beaches, but the costs are high."
According to one study that will soon be published, the cost of maintaining
East and Gulf Coast beaches will run anywhere from $10 to $100 billion. A
series of aerial photographs taken since 1938, for instance, shows that the
Blackwater National Wildlife Refuge on the eastern shore of the Chesapeake Bay,
one of the most important East Coast waterfowl sanctuaries, is in a state of
disintegration because of rising sea level. Human activity can hasten such
Some of the other
threats posed by a one- to three-foot rise in sea level include increased
salinity of drinking water; saline intrusion into river deltas and estuaries,
which would imperil fisheries; the inundation of wetlands, cypress swamps and
adjacent lowlands; increased flooding in populated areas, which would
necessitate the building of costly flood protection systems, such as sea walls;
the disappearance of beaches all over the world.
Then there are
these further dire possibilities:
meteorologist Kerry Emanuel at MIT indicate that more severe hurricanes are
likely because of warmer oceans. Such storms could increase in ferocity by as
much as 60% over current maximums.
?Radical change in
the Antarctic ice sheet could have severe consequences. Antarctica has 91% of
the world's ice (only 1% is locked up in mountain glaciers). If the Antarctic
ice sheets were to melt completely, the global sea level would rise 15 to 20
feet. No one expects that to happen. At currently projected rates, the
greenhouse effect and global warming are not expected to have a major impact on
the Antarctic ice sheet for several centuries. But no one predicted holes in
the ozone layer, and as Dr. Stanley S. Jacobs, a senior staff associate at
Lamont-Doherty, said in a recent article in Oceanus magazine: " Antarctica
may be a wild card in the deck, but who can say the deck is not stacked, with
Nature setting up the sting?"
Couple all the
greenhouse effects with increased ultraviolet radiation, and we have written
the prescription for disaster—ecological, economical and political.
It is ludicrous to
assume that we could rapidly adapt to such changes. "Infrastructures of
society, such as water supplies, transportation networks, and land use patterns
have evolved over centuries in response to prevailing climate," says Dr.
Gordon J. MacDonald, a former professor of geophysics at Dartmouth who's now
vice-president and chief scientist of the Mitre Corporation, a nonprofit
research organization. "Significant changes in climate over decades will
exert profound disruptive forces on the balance of infrastructures."