The Intergovernmental Panel on
Climate Change estimates that
Earth will warm between two
and six degrees Celsius over the
next century. The range in
estimate comes from running
different emission scenarios
through several different global
climate models. Scenarios that
assume that people will burn
more and more fossil fuel
provide the estimates in the top
end of the temperature range,
Global warming will shift major
climate patterns, possibly
prolonging and intensifying the
current drought in the U.S.
Southwest. The white ring of
bleached rock on the once-red
cliffs that surround Lake Powell
indicate the drop in water level
over the past decade, the
result of repeated winters with
low snowfall.