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projected rate of increase by
2100 is anywhere from 9 to
88 cm, depending on which
climate model is used. What
this means is that low-lying
coastal areas will experi-
ence fl ooding and increased
erosion along the coastline,
endangering housing and
communities. For instance,
about 17 million people live
less than one meter above sea
level in Bangladesh, and are
at risk due to rising sea levels.
Furthermore, many major
cities are just above sea level,
and could also suffer from
rising sea levels. A rise in sea
level at the upper end could
completely submerge such
island nations as the Mal-
dives in the Indian Ocean
(
continuation of the retreat of glaciers
and ice caps, with a decrease in north-
ern hemisphere snow cover and sea ice.
What do all these predictions mean
to you? With increasingly hotter sum-
mers and greater frequency of drought,
expect to see higher food prices as crop
yields decrease. There will also be an in-
creased risk of wildfi res, and deadly heat
waves will result in more heat-related
deaths, such as occurred in Europe
during the summer of 2003.
As climates change, diseases such as
malaria are easily spreading into areas
of warmer, wetter climates. Disease-
carrying mosquitoes are expanding their
reach as climate changes allow them to
survive in formerly inhospitable regions.
Higher temperatures will affect
regional water supplies, creating poten-
tial water crises in the western United
States within the next 20 years, as well
as other areas such as Peru and west-
ern China. Just as many regions will
experience longer and hotter summers,
other areas will suffer from intense and
increased rainfall, which will result in
severe fl ooding and landslides.
Everyone is vulnerable to weather-
related disasters; however, large-scale
changes brought about by climate
change will impact people in poor
countries more than those in the more
industrialized countries. However,
whether these climate changes are part
of a natural global cycle taking place
over thousands or hundreds of thou-
sands of years—that is, on a geological
time scale—or are driven, in part, by
human activities, is immaterial. The
bottom line is that we already are, or
eventually will be, affected in some
way, be it economic or social, by the
climate changes that are taking place.
Figure 1).
Based on various climatic
computer models and taking
into account the complex-
ity and variability of the
atmospheric-oceanic system,
most predictions show Earth's average
surface temperature increasing by 1.4 to
5.8°C during the period of 1990-2100.
This will result in widely varying re-
gional responses, such that land areas
will warm more and faster than ocean
areas, particularly in the high latitudes
of the northern hemisphere. Expect to
see more hot days and heat waves over
nearly all the land areas, with increasing
drought frequency within all continen-
tal interiors during the summer
(
◗
◗
Figure 2
Withered corn due to drought conditions.
trends. For example, there is compel-
ling evidence of climate variability or
extremes on a regional scale, but on
a global scale, there is currently little
evidence of a sustained trend in climate
variability or extremes. That doesn't
mean that we can ignore the overall
increase in average global surface tem-
peratures, because if left unchecked, such
changes can have signifi cant environ-
mental, ecological, and economic effects.
So what are some of the effects we
should be worried about? For start-
ers, there is the problem of rising sea
level. During the past 100 years, global
sea level has been rising at an average
rate of 1 to 2 mm per year, and the
Figure 2). There will also be increased
precipitation during the 21st century,
particularly in the northern middle
to high latitudes. And expect to see a
◗
consequence of this warming, rainfall patterns will shift dra-
matically, which will have a major effect on the largest grain-
producing areas of the world, such as the American Midwest.
Drier and hotter conditions will intensify the severity and
frequency of droughts, leading to increased crop failure and
higher food prices. With such shifts in climate, Earth's des-
erts may expand, with a resulting decrease in the amount of
valuable crop and grazing lands.
Continued global warming will result in a rise in mean sea
level as icecaps and glaciers melt and contribute their water
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