| Cymbal Man Freq. 2004-11-20, 11:06 am |
| Last update: November 19, 2004 at 9:37 PM
Capricious weather? Get used to it
Paul Douglas, Special To The Star Tribune
November 20, 2004
More tornadoes, more frequent spring flooding, unnatural summer frosts and
late-November green lawns in Minnesota.
What is going on?
America's weather has never been more volatile, adversely affecting more people
than ever before. At the same time, Minnesotans have been experiencing a run of
unseasonably mild weather that will persist and bring with it wilder swings in
the climate.
That means it's a good bet that when it comes to the state of our agitated
weather, we'll continue to have plenty to talk about. Just this year we've felt
August windchill and seen frost in the Arrowhead, with tornadoes touching down
as late as Oct. 29 in central Minnesota.
We had our 10th-warmest autumn, following the 14th-coolest summer in modern-day
records, which began in 1891. Minnesotans detected 58 tornadoes in 2004, second
only to 2001, when a record 74 were observed.
Never has the weather been so capricious and unpredictable.
And never have the reasons been in such dispute. And although the perception
among many is that we're seeing less snowfall than in previous generations,
snowfall is increasing. It's just that warmer weather, especially at night,
means it's melting faster.
Meteorologists have documented a 20 percent increase in heavy rain and snow
since 1900. And since meteorological spring comes roughly a week sooner than it
did in the 1970s, the potential for rapid snowmelt, runoff and spring flooding
has increased.
These shifts in weather patterns could well alter how we live in the 21st
century, affecting the kinds of weather-resistant crops Minnesota farmers plant.
They could also lead to stormproof designs for our homes and offices,
hail-resistant car surfaces and urban infrastructure better able to withstand
rainfall runoff and flooding.
Why is our weather more severe? There are no simple explanations. Our atmosphere
is incredibly complex and chaotic. Proving cause and effect is nearly
impossible. But evidence is mounting that a warmer climate is sparking more
weather extremes, especially over northern latitudes from Alaska to Minnesota to
New England. Warmer air holds more moisture, which increases the potential for
flooding rains, tornadoes and hail.
Our climate is evolving, and Minnesotans may have a front-row seat, among the
first states to witness symptoms of a warmer planet.
Four hurricanes struck Florida this year; that hadn't happened since 1896.
Nationwide, the tornado count stands at a record 1,584. The 10 costliest storms
on record have occurred in the past 10 years.
Globally, temperatures have increased slightly more than 1 degree Fahrenheit
since 1900, but ground-based instruments and weather satellites have documented
a rise of 3.5 to 5.5 degrees over northern latitudes. Polar ice is thinning,
glaciers are melting and receding, and trees are dying by the millions across
Alaska and Canada.
And it's a vicious cycle: Melting snow and ice leads to darker, snow-free ground
absorbing even more sunlight, triggering more warming and more melting.
Sen. John McCain, R-Ariz., visited the arctic regions of Iceland and Norway late
this summer and, according to the New York Times, he was disturbed by the rate
of warming he witnessed. "The Inuit language for 10,000 years has never had a
word for robin," he said. "And now there are robins all over their villages."
For most scientists, global warming has gone from theory to reality. There are
still arguments about how much of the warming is natural, and how much can be
linked to the burning of fossil fuels. Either way, there's little doubt that
northern latitudes are feeling the heat.
The changes in Minnesota's weather and longer-term climate haven't been as
dramatic as in Alaska. Yet evidence is mounting that Minnesota's winters are
shorter than they were even a generation ago, and milder, especially at night.
Prof. Mark Seeley, who studies meteorology and climatology at the university of
Minnesota, said his records show that we have had eight consecutive Novembers in
Minnesota mild enough to play golf. "This trend has been mostly unprecedented,
historically," he said.
His research also shows that since 1997-1998, when winter weather was the
warmest in more than 100 years, the trend for warmer-than-normal readings during
the winter has been, in his words, remarkable.
There is a potential upside: Seeley estimates that we've spent 9 percent less
than average on our heating bills since 1997.
Dan Luna, chief of river forecasting at the National Weather Service in
Chanhassen, said: "It would be hard-pressed for anyone to argue that we're not
seeing evidence of warming. 'Why?' is another question, but we're just not
getting the really cold winters anymore."
Scientists aren't surprised that a warmer environment leads to a higher number
of extreme weather events, in Minnesota and nationwide.
Another key factor: better detection in the forms of new technology and more
trained weather spotters out in the field. According to Craig Edwards, chief of
the National Weather Service office in Chanhassen, the newest technology is so
sensitive that it's picking up previously unnoticed tornadoes.
Costly decisions
And while our weather becomes more extreme, we've positioned ourselves for
expensive consequences. Colorado State university Prof. Roger Pielke, who
studies the societal impacts of severe weather, said: "There have always been
ups and downs and severe events, but as a nation, we are far more vulnerable
than ever before." More people than ever are living in flood plains, and
farmland has been transformed into housing subdivisions, increasing the
potential for tornado damage and casualties.
Pielke said we're becoming a nation of sitting ducks. Within 15 years, nearly
three in four Americans will live on or near the coast - that means in the
potential path of hurricanes.
J. Drake Hamilton, science adviser for ME3 (Minnesotans for an Energy Efficient
Economy), said she's concerned about possible shifts in our weather patterns and
the growing number of severe weather events.
"Right now, the climate of Minnesota, if we do nothing, will change about 100
times faster than it has in the past, getting much warmer," Hamilton said.
"Within our lifetime, winters in Minnesota will become more like winters in
Chicago - warmer with less snow and more precipitation coming as rain."
Hamilton's concerns go beyond winter conditions to quality-of-life issues: the
health of our lakes, the kinds of trees that can grow in Minnesota and the
stresses of a hotter, drier climate on Minnesota's crops.
According to Prof. emeritus H.E. Wright of the university of Minnesota's
Department of Geology and Geophysics: "The most striking thing about recent
trends is the very rapid changes that are taking place. These temperature
increases are unusual in their intensity and the sheer rate of change."
Nineteenth-century humorist Kin Hubbard gently reminded Americans not to knock
the weather. He speculated that nine-tenths of the people he knew couldn't start
a conversation if the weather didn't change once in a while. Judging by recent
weather trends, that shouldn't be a problem.
Paul Douglas, senior meteorologist of the WCCO Weather Team, is author of the
new book "Restless Skies."
|