Western North America Faces 21st Century 'Mega-drought'
The
climate's "new normal" for most of the coming century will
parallel the long-term drought that hit western North America from
2000 to 2004 - the most severe drought in 800 years - scientists
report in a study published Sunday.
ENS,
30
July, 2012
"The
severity and incidence of climatic extremes, including drought, have
increased as a result of climate warming," the researchers said,
adding that these long-term trends are consistent with a 21st century
"megadrought."
Crops
and forests died and river basins dried, but as bad as conditions
were during the 2000-04 drought, in the future they may be seen as
the good old days, a group of 10 researchers warned Sunday in the
journal "Nature Geoscience."
Pinyon
pine forests near Los Alamos, New Mexico, had begun to turn brown
from drought stress in 2002, left. Another photo taken in 2004 from
the same vantage point, right, show them grey and dead. (Photo by
Craig Allen, U.S. Geological Survey)
Climate
models and precipitation projections indicate this period will be
closer to the "wet end" of a drier hydroclimate during the
last half of the 21st century, the scientists said.
"Climatic
extremes such as this will cause more large-scale droughts and forest
mortality, and the ability of vegetation to sequester carbon is going
to decline," said Beverly Law, a co-author of the study,
professor of global change biology and terrestrial systems science at
Oregon State University, and former science director of AmeriFlux, an
ecosystem observation network.
The
2000-04 drought had the effect of amplifying climate change as
vegetation withered and could no longer take up the greenhouse gas
carbon dioxide from the atmosphere.
This
drought cut carbon sequestration by an average of 51 percent in the
western United States, Canada and Mexico, the scientists calculate,
although some areas were hit much harder than others. As the plants
died, they released more carbon dioxide into the atmosphere, with the
effect of amplifying global warming.
"During
this drought, carbon sequestration from this region was reduced by
half," Law said. "That's a huge drop. And if global carbon
emissions don't come down, the future will be even worse."
The
effects are driven by human-caused increases in temperature, with
associated lower soil moisture and decreased runoff in all major
water basins of the western United States, researchers said in the
study.
Drought
has affected Colorado farm lands near Strasburg, Colorado, July 21,
2012. (Photo by Lance Cheung, USDA)
It
is not clear whether or not the current drought in the West and
Midwest, now being called one of the worst since the Dust Bowl, is
related to these same forces, Law said. This study did not address
that, and there are some climate mechanisms in western North America
that affect that region more than other parts of the country.
But
in the West, this multi-year drought was unlike anything seen in many
centuries, based on tree ring data. The last two periods with drought
events of similar severity were in the Middle Ages, from 977-981 and
1146-1151. The 2000-04 drought affected precipitation, soil moisture,
river levels, crops, forests and grasslands.
Ordinarily,
Law said, the land sink in North America is able to sequester the
equivalent of about 30 percent of the carbon emitted into the
atmosphere by the use of fossil fuels in the same region.
But
based on projected changes in precipitation and drought severity,
scientists said that this carbon sink, at least in western North
America, could disappear by the end of the century.
"Areas
that are already dry in the West are expected to get drier," Law
said. "We expect more extremes. And it's these extreme periods
that can really cause ecosystem damage, lead to climate-induced
mortality of forests, and may cause some areas to convert from forest
into shrublands or grassland."
During
the 2000-04 drought, runoff in the upper Colorado River basin was cut
in half. Crop productivity in much of the West fell five percent. The
productivity of forests and grasslands declined, along with
snowpacks.
Evapotranspiration
decreased the most in evergreen needleleaf forests, about 33 percent.
Although
regional precipitations patterns are difficult to forecast, the
researchers said in this report that climate models are
underestimating the extent and severity of drought, compared to
actual observations.
They
say the situation will continue to worsen, and that 80 of the 95
years from 2006 to 2100 will have precipitation levels as low as, or
lower than, this "turn of the century" drought from
2000-04.
This
research was supported by the National Science Foundation, NASA, U.S.
Department of Energy, and other government agencies. The lead author
was Christopher Schwalm at Northern Arizona University. Other
collaborators were from the University of Colorado, University of
California at Berkeley, University of British Columbia and San Diego
State University.
Record
high of 111 degrees for Little Rock
Triple-digit
heat intensified across Arkansas on Monday, setting records in at
least two cities and increasing the danger for wildfires.
30
July, 2012
Temperatures
exceeded 100 in some areas, and are expected to stick around for much
of the week. Low humidity also is settling in, increasing the threat
for wildfires.
The
daytime high reached 111 degrees in Little Rock, which not only broke
the date's record but marked the third-highest temperature ever
recorded in the state's capital city. The previous record for July 30
was 108 degrees in 1986.
Little
Rock reached 114 degrees last year on Aug. 3, the city's hottest day
in 132 years of records. The city's second-highest temperature on
record occurred July 31, 1986, when it hit 112 degrees.
Also
Monday, a record was set in Jonesboro, where the mercury peaked at
104, a degree higher than the record set in 1986.
National
Weather Service senior forecaster Joe Goudsward warned that little
relief from the high temperatures is expected soon....
Phoenix
covered in blanket of dust for second time in a week as massive cloud
rolls in from desert.
30
July, 2012
A
second cloud of yellow in less than a week overwhelmed suburban
Phoenix on Sunday, mixing with torrential rains and gusty winds that
wreaked havoc on midday traffic in the area.
The
thick wall of dust, known as a haboob, which is Arabic for
'strong wind,' was seen making its way through the town of Laveen
about eight miles southwest of downtown Phoenix.
The
greater Phoenix area and northwest and north central Pinal County
were under a dust storm warning that expired at 7pm on Sunday.
Second
coming: A large dust cloud was seen making its way through the
Phoenix suburb of Laveen on Sunday
This
comes just days after an enormous dust cloud measuring around 2,000
feet tall and almost 100km wide swept over the city, traveling at
35mph. The dust cut power to some 9,000 homes and caused
disruptions at the local airport.
Caused
by Arizona's monsoon season which begins in early June and runs
through till the end of September, haboob's only occur in Africa, the
Middle East, Australia and Phoenix, Arizona.
Known
as the granddaddy of dust storms, the haboob is a rare event and is
caused by loose dust being blown upwards in the absence of rain and
collecting skywards where it is then propelled by another more
distant thunderstorm brewing behind it.
Despite
some of the 1.5 million residents of Phoenix objecting to the term
haboob being used, meteorologists in the city confirmed that they
have been using the Arabic word to describe the massive dust storms
for over 30 years.
'I
think what's going on is that we've had a higher frequency of
stronger dust storms over the last couple of years and the term has
been in play much more because of that,' said Ken Waters of the
Phoenix National Weather Service office to KPHO.
Blowing
gusts of up to 50 mph at Phoenix Sky Harbor Airport, the haboob is
destructive because of the fine dust particles that manage to
permeate everywhere during the storm.
The
2,000 foot tall haboob cloud covers the city of Phoenix, Arizona
cutting power to 9,000 homes
The
haboob phenomenon affects Phoenix during the months of June through
September which is Arizona's monsoon season
The
haboob covered cities in the metropolitan Phoenix area such as
Scottsdale, Gilbert, Mesa, Apache Junction, Santan Valley, Chandler,
Casa Grande and downtown Phoenix
Winds
were measured as high as 50 miles per hour at Phoenix Sky Harbor
Airport which closed for 20 minutes because of the dust cloud
'The
dust gets into everything ... It gets into electronics, it gets into
every nook and cranny,' said Penn State University meterologist Fred
Gadomski to NPR.
Familiar
to millions of movie-goers from films such as 'The Mummy' or
'Hidalgo', the Haboob was witnessed by Phoenix New Times freelance
photographer Andrew Pielage, who watched the storm unfold from a
mountain viewpoint.
'It
is one thing to see it from the ground, but when you are on top of a
mountain and you still have to look up to see the top of it you
really start to grasp the size and magnitude of the haboob,' said
Pielage to the Examiner.com.
The
haboob temporarily blocked out the sun and covered everything in a
layer of dust
An
Arizona researcher who studies haboobs said there could be hidden
health impacts for millions of people living in the state’s dust
zone.
According
to William Sprigg, of the University of Arizona’s Institute of
Atmospheric Physics, dust storms carry a noxious mix of fungi, heavy
metals from pollutants, chemicals and bacteria that could lead to
cardiovascular and eye disease, and other illnesses.
‘We
already know the cost of these storms in general,’ he told the
Arizona Republic. ‘I would like to see a much more thorough
examination of the effects of the dust on the region.’
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