|
ISWS climate
models estimate future extreme heat waves
Send a link to a friend
[July 15, 2010]
CHAMPAIGN
-- Heat waves that we have experienced
recently will likely pale in comparison to
what's ahead in 50 years if greenhouse gas
emissions continue at the current rate,
according to Xin-Zhong Liang, Ph.D.,
Illinois State Water Survey atmospheric
scientist at the University of Illinois and
assistant professor in the Department of
Atmospheric Sciences. |
 Using
regional climate models coupled with general
circulation models that are continuously
fine-tuned, Liang has estimated various
scenarios based on pollution emission
rates. All scenarios project the potential
for significant changes in temperatures,
precipitation and other climate indexes
across the U.S.
Results for the high-emissions scenario
project a high probability of severe heat
waves by the end of the 21st century. In
particular, annual three-day heat wave
temperatures would increase by 5 to 14
degrees F in most areas, and the number of
heat-wave days would increase by 30 to 60
per year over much of the western and
southern U.S., with slightly smaller
increases elsewhere.
For an emissions scenario assuming
continued heavy use of fossil fuels, by the
end of the century Chicago may see as many
as 30 days when the temperature exceeds 100
degrees, compared with one to two days now.
"Models show a high probability that heat
waves will be significant," Liang said. "If
that happens, the big cities such as Chicago
and New York will be seriously in
trouble. We have to be prepared for that."
Extreme heat can cost lives, such as in
1995 in Chicago, where hundreds of deaths
were attributed to a five-day heat wave.
Projected annual heat-wave temperatures
tend to be lower for coastal cities, such as
Los Angeles, Miami and the northeastern
U.S., compared with inland locations.
In Chicago, where the hottest temperature
is usually 90 degrees, the projected
temperature increase for the high-emissions
scenario is to 104 degrees. This is
equivalent to the hottest days in Phoenix,
Ariz., for 1991-2000.
[to
top of second column] |
Similar changes of a lesser magnitude are
projected by midcentury under reduced
emission scenarios.
Other findings in a study of the
northeastern U.S. show that summertime
rainfall is projected to decrease over much
of the region, particularly along the
northern coastal regions, and water
evaporation will increase, adversely
affecting water supplies. The significant
effects on water availability and human
health are expected to occur in the second
half of the 21st century, Liang said.
___
The Illinois State Water Survey is a
division of the Institute of Natural
Resource Sustainability at the University of
Illinois at Urbana-Champaign.
[Text from
file received from the
Illinois State Water Survey]
 |
