Environmental Engineering Reference
In-Depth Information
When Pinatubo blew its stack in 1991, it sent nearly 20 million
tons of sulfur dioxide into the stratosphere. Global temperatures
dropped temporarily (1991-1993) by about 1°F, according to the
U.S. Geological Survey.
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Climate trek.
Just as the volcanic ash and the Asian dust cloud
progressed around the globe, so do climate and weather patterns,
which affect the amount of precipitation that falls, how it falls—
as severe storms and fl ooding, snow, and so on—where it falls or
doesn't fall, and its effect on water supplies.
What takes place in the Pacifi c Ocean, for example, affects the
weather across North America, because weather moves from west
to east, says Le Comte, also a contributing editor to
Weatherwise
Magazine
. “Long-range forecasters pay attention especially to the
tropical Pacifi c, where a tremendous amount of warm water and
convection—warm air rising—means less stable air and more thun-
derstorms. That same energy rising into the atmosphere fuels the
jet stream. All this and more contribute to storm and precipitation
patterns across the United States.”
That precipitation, of course, affects the amount of water
in U.S. lakes, rivers and streams, recharge of aquifers, and so on.
That's one reason El Niño and La Niña are perennial hot top-
ics. Both concern changes in surface water temperatures in the
Pacifi c and resulting weather patterns and precipitation across
the United States. El Niño generally means a more active south-
ern jet stream, which can lead to storms and more rain across the
United States. La Niña, on the other hand, means colder ocean sur-
face temperatures and drier U.S. weather.
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Climate change progresses around the globe, too. But the
global connections between, for example, drought in Africa
and the United States are inadequately understood, says Gleick.
Nonetheless, he says, “Climate change is a very real problem
that already has had impacts on water resources, reducing snow-
fall in mountainous areas of the United States like the Sierra
Nevadas and the Rocky Mountains, and in the Himalayas on
the other side of the globe. Climate change also affects the fre-
quency and intensity of storms and drought, with increasing
impacts in the
southwestern
United States
and
sub-Saharan
Africa,” Gleick adds.
