Scientists: Weather extremes consistent with global warming
Pastor Dale Morgan
Scientists: Weather extremes consistent with global warming*
By Larry Wheeler, Gannett News Service
WASHINGTON — If you think the weather is getting more extreme, you're
right — and global warming caused by human activity probably is the
reason, according to a report released Thursday by a panel of government
scientists.
The report comes as the Midwest copes with record rainfall and
catastrophic flooding.
There is strong evidence the increasing frequency of extreme rain, heat,
drought and tropical storms is caused by global climate change,
according to the report from the U.S. Climate Change Science Program.
"Changes in some weather and climate extremes are attributable to
human-induced emissions of greenhouse gases," the study authors concluded.
The report is a synthesis of the latest research on extreme weather in
the U.S. and comes after nearly six months that saw a record number of
tornadoes, unusual winter warmth and record-setting precipitation in
many regions.
The most extreme weather event so far this year, the Midwest floods,
continues to unfold.
Climate change likely played an important role in setting up conditions
that led to the region's second 500-year flood event in 15 years,
according to experts.
As global temperatures have increased in recent years, so have sea
surface temperatures. Warmer oceans evaporate more water vapor into the
atmosphere. Water vapor is the fuel that drives rainstorms.
"When you get a system like we have had over the past month or two in
the Midwest, this persistent pattern of low pressure and fronts in the
area, now there is more moisture to work with and they produce
frequently heavy rains," said Ken Kunkel, interim chief of the Illinois
State Water Survey office and one of the authors of the report released
Thursday.
It's the opposite of the severe drought that helped create the Dust Bowl
of the 1930s that caused extensive environmental and agricultural damage.
"The data are quite clear," said Kunkel, who specializes in studying
U.S. extreme precipitation. "We're in an era when these heavy rain
events have been occurring more frequently."
The report also concluded that:
• Human-caused warming likely has caused much of the increase in average
and extreme temperatures observed in the U.S. over the past 50 years.
• Heavy precipitation events have increased over the past 50 years.
That's consistent with increases in atmospheric water vapor associated
with human-caused increases in greenhouse gases.
• Droughts are becoming more severe in some regions, though there are no
clear national trends.
• The power and frequency of Atlantic hurricanes have increased
substantially in recent decades, likely driven by human-caused increases
in sea surface temperatures. However, the number of hurricanes making
landfall does not appear to have increased over the past century.