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CLIMATE: New Science: Global Warming Strengthens Hurricanes, May Be Inevitable September 16, 2005 10:49 AM

New Science: Global Warming Strengthens Hurricanes, May Be Inevitable
ClimateArk a project of Ecological Internet, Inc. -- ClimateArk - Climate Change Portal -- Climate Change Blog -- Climate Change Newsfeed
September 16, 2005
OVERVIEW & COMMENTARY by Dr. Glen Barry, ClimateArk

A new "Science" journal article by a group of meteorologists reports a
striking 80% increase worldwide in the abundance of the most powerful
hurricanes during the past 35 years (also known as cyclones and monsoons).
Because the results were similar across the globe, the scientists
discounted natural variability as the cause.  Entitled "Changes in
Tropical Cyclone Number, Duration, and Intensity in a Warming
Environment", the scientific study is the second in six weeks to connect
climate change's warming of oceans and intensified hurricanes.  Global
warming and hurricanes are naturally linked by the storms' feeding upon
ocean heat.  Tropical storms draw their energy upward from warm ocean
water to drive their winds.

The bottom line is we can not assume that Hurricane Katrina was a once of
a lifetime event.  This is not alarmist - it is prudent given the
potential for dramatic climate change caused disasters in the future.
Displaying customary scientific caution, we are advised not to blame
Katrina's damage on global warming.  Other factors such as densely
populated coasts may be more causative of increasing storm damage.  And no
long-term trend in the number of storms per year has been found.

Yet, in the absence of other studies proving otherwise, the state of the
science is that hurricanes are stronger as a result of global warming.
This is consistent with what climate change science has long predicted -
and what we know about how hurricanes form.  Sure there are questions,
there always are with science.  There is not yet certainty, but we are way
past the point where we can afford to ignore the matter.

Another forthcoming study (Item #3 below) indicates serious climate change
impacts are inevitable given the state of melting Arctic ice.  On the
basis of record loss of sea ice in the Arctic this summer, scientists fear
that the Arctic has now entered an irreversible phase of warming which
will accelerate the loss of the polar sea ice that has helped to keep the
climate stable for thousands of years.

There continues to be a huge failure of American climate change
leadership, as generally policy-makers and the media are not seriously
discussing the possibility that Hurricane Katrina was intensified by
global warming.  Bush's global warming failure goes beyond not ratifying
Kyoto.  There has been not a word post-Katrina about increasing
preparations for climate change, or limiting emissions to move towards
climate stabilization. 

This head in the sand response is dangerous and irresponsible.  I renew my
assertions made in a recent essay entitled at "Hurricane an Unnatural
Disaster, Root Causes Are Ecological" on my personal blog at .  We must get to the ecological root
causes, responsible for the severity of the Hurricane Katrina disaster, in
order to prevent and/or minimize future disasters enabled by collapsing

Make Comments:


Title:  Study links severest storms, warmer seas
Source: Copyright 2005, Washington Post
Date: September 16, 2005
Byline:  Juliet Eilperin

A scientific paper being published today concludes that warming sea
temperatures have been accompanied by a significant global increase in the
most destructive hurricanes, adding fuel to an international debate over
whether global warming contributed to the devastation wrought by Hurricane

The study, in the journal Science, is the second in six weeks to draw
similar conclusions, but other climatologists dispute the findings and
argue that a recent spate of severe storms reflects nothing more than
normal weather variability.

Katrina's destructiveness has given a sharp new edge to the debate over
whether the United States should do more to curb greenhouse gas emissions
linked to global warming. Critics have pointed to Katrina as a reason to
act, while skeptics say climate activists are capitalizing on a disaster
to further their agenda.

According to data gathered by researchers at Georgia Tech's School of
Earth and Atmospheric Sciences and the National Center for Atmospheric
Research, the number of major hurricanes worldwide has nearly doubled over
the past 35 years, even though the total number of hurricanes, including
weaker ones, has dropped since the 1990s. Katrina was a Category 4 storm.

Using satellite data, the four researchers found that the average number
of Category 4 and 5 hurricanes - those with winds of 131 mph or higher -
rose from 10 a year in the 1970s to 18 a year since 1990. Average tropical
sea surf  [ send green star]
 September 16, 2005 10:51 AM

surface temperatures have increased as much as 1 degree Fahrenheit
during the same period, after remaining stable between 1900 and the

Georgia Tech atmospheric scientist Judith Curry - who coauthored the study
with colleagues Peter Webster and Hai-Ru Chang, and NCAR's Greg Holland -
said in an interview that their survey, coupled with computer models and
scientists' understanding of how hurricanes work, has given them a better
sense of how rising sea temperatures are linked to more intense storms.

"There is increasing confidence, as the result of our study, that there's
some level of greenhouse warming in what we're seeing," Curry said. "Is it
the whole story? We don't know."

Higher ocean temperatures result in more water vapor in the air, which,
combined with certain wind patterns, helps power stronger hurricanes,
Webster said. Small increases in sea temperature can "exponentially
provide more and more fuel for the hurricanes."

Other studies and computer models have also pointed to a rise in storm
intensity: Massachusetts Institute of Technology scientist Kerry Emanuel
wrote last month in the journal Nature that the duration and maximum wind
speeds of storms in the North Atlantic and North Pacific have increased
about 50 percent since the mid-1970s. The storms' growing violence stemmed
in part from higher ocean temperatures, he concluded.

Some researchers, however, question the connection with more severe
hurricanes and cyclones. Gerry Bell, the lead seasonal hurricane
forecaster at the National Oceanic and Atmospheric Administration, said
the rise in strong hurricanes reflects a natural weather pattern spanning
several decades. Hurricanes in the Atlantic were more powerful in the
1950s and '60s, weakened in the 1970s, '80s and early '90s and have
strengthened since 1995.

"It's not linked to global warming or anything like that," Bell said.
"This is normal climate variability. It's just that this trend lasts for

Florida State University meteorology and oceanography professor James
O'Brien said his survey of government data on Atlantic storms between 1850
and 2005 shows "there's no indication of an increase in intensity."

But both Emanuel and Gavin Schmidt, a NASA climatologist, said today's
paper is important because it examines worldwide patterns.

"If you look it on the global basis, it makes that signal of global
warming easier to see," Schmidt said. "You have to be extremely
conservative, with a small 'c,' to think (rising sea temperatures and
stronger hurricanes) are not related."

And some hurricane experts who have previously questioned the influence of
global warming now say the evidence is mounting that it has contributed to
recent intense tropical storms.

Florida International University researcher Hugh Willoughby, who headed
NOAA's hurricane research division between 1995 and 2003, said the recent
two hurricane studies are "very persuasive" and helped move him "toward
the climate corner" of the debate.

"It's really hard to find any holes in this, and I'm the kind of person
who's inclined to look for holes," he said of the new paper in Science.
The arguments against the connection between climate change and more
intense storms, he added, are "looking weaker and weaker as time goes

Katrina reanimated a transatlantic argument over global warming policy as
critics of the Bush administration have seized on it to promote mandatory
limits on greenhouse gas emissions.

"The American president shuts his eyes to the economic and human damage
that the failure to protect the climate inflicts on his country and the
world through natural catastrophes like Katrina," Germany's environmental
minister Jurgen Trittin wrote in an opinion piece.

Bill Holbrook, spokesman for U.S. Senate environment committee Chairman
James Inhofe, R-Okla., said the senator has no intention of pushing for
new emission curbs. "It is reprehensive for a politician to promote an
agenda by taking a tragedy Americans feel so deeply about, particularly
when there is no merit to his ideas," Holbrook said.

Arguing that the science of global warming remains uncertain, Bush in 2001
disavowed the Kyoto Treaty that sets mandatory targets for reducing
greenhouse gas emissions, and he has pursued policies calling for more
research and voluntary efforts to limit emissions.

ITEM #2:
Title: More Strong Katrina-Like Hurricanes Reported
Source: Copyright 2005, Reuters
Date: September 16, 2005
Byline:  Deborah Zabarenko

WASHINGTON - The number of strong hurricanes -- like the devastating
Katrina -- significantly increased in the last 35 years, fueled by hotter
seas that have been linked to global warming, researchers reported on

Twice as many of the most powerful hurricanes, those ranked Category 4 or
5, have been detected since 1990 as were seen in the period from 1970 to
1985, scientists found in a global survey.
But the overall number of hurricanes has decreased during the last decade,
the researchers wrote in a study published in the journal Science.

The rise in intense, destructive hurricanes worldwide goes along with a
rise in sea surface temperatures, said Judith Curry of the Georgia
Institute of Technology.

"This trend in sea surface temperature that's sort of relentlessly rising
and the hurricane intens  [ send green star]
 September 16, 2005 10:52 AM

intensity that's relentlessly rising (means that) it's
with some confidence we can say that these two things are connected and
that there's probably a substantial contribution from greenhouse warming,"
Curry said in a telephone news briefing.

Warm sea surfaces help fuel hurricanes, and the higher the temperature at
the water's surface, the stronger the hurricane can become, Georgia
Institute of Technology's Peter Webster explained.

Water vapor that evaporates from the sea's surface into the atmosphere
eventually condenses as rain, releasing heat and driving a tropical
cyclone -- the swirling pattern that can beget a hurricane.


The warmer the sea surface, the greater amount of potential evaporation
and the greater the fuel for a possible hurricane, Webster said. And even
small rises in sea surface temperature can cause rapid rises in

The surface temperature in the Atlantic Ocean has risen about 1 degree
Fahrenheit (.5 degree Celsius) since 1970, the researchers said.

They noted, however, that only 12 percent of the world's hurricanes form
in the Atlantic, so they looked at global data dating back to 1970. They
discovered that the number and duration of hurricanes has remained
generally stable, but the intensity has increased.

Because the results were similar across the globe, the scientists
discounted natural variability as the cause.

These findings were in line with research published recently in the
journal Nature, reporting that hurricanes have become more destructive
over the last 30 years.

Hurricane Katrina was considered a Category 5 storm by the researchers,
even though it had weakened to Category 4 when it came onshore on the US
Gulf coast, on Aug 29.

The US National Hurricane Center has forecast an extremely active Atlantic
hurricane season, with 9 to 11 hurricanes, including 7 to 9 major
hurricanes, from July to November.

Category 5 is the highest rating on the Saffir-Simpson scale of hurricane
intensity, meaning the storm has winds greater than 155 miles (249 km) an

The next-highest rating, Category 4, is a storm packing winds between 131
and 155 miles (210 and 249 km) an hour.

To be classified as a hurricane, tropical storms must have winds above 74
miles (119 km) an hour.

Title: Global warming 'past the point of no return'
Source: Copyright 2005, Independent
Date: September 16, 2005
Byline:  Steve Connor

A record loss of sea ice in the Arctic this summer has convinced
scientists that the northern hemisphere may have crossed a critical
threshold beyond which the climate may never recover. Scientists fear that
the Arctic has now entered an irreversible phase of warming which will
accelerate the loss of the polar sea ice that has helped to keep the
climate stable for thousands of years.

They believe global warming is melting Arctic ice so rapidly that the
region is beginning to absorb more heat from the sun, causing the ice to
melt still further and so reinforcing a vicious cycle of melting and

The greatest fear is that the Arctic has reached a "tipping point" beyond
which nothing can reverse the continual loss of sea ice and with it the
massive land glaciers of Greenland, which will raise sea levels

Satellites monitoring the Arctic have found that the extent of the sea ice
this August has reached its lowest monthly point on record, dipping an
unprecedented 18.2 per cent below the long-term average.

Experts believe that such a loss of Arctic sea ice in summer has not
occurred in hundreds and possibly thousands of years. It is the fourth
year in a row that the sea ice in August has fallen below the monthly
downward trend - a clear sign that melting has accelerated.

Scientists are now preparing to report a record loss of Arctic sea ice for
September, when the surface area covered by the ice traditionally reaches
its minimum extent at the end of the summer melting period.

Sea ice naturally melts in summer and reforms in winter but for the first
time on record this annual rebound did not occur last winter when the ice
of the Arctic failed to recover significantly.

Arctic specialists at the US National Snow and Ice Data Centre at Colorado
University, who have documented the gradual loss of polar sea ice since
1978, believe that a more dramatic melt began about four years ago.

In September 2002 the sea ice coverage of the Arctic reached its lowest
level in recorded history. Such lows have normally been followed the next
year by a rebound to more normal levels, but this did not occur in the
summers of either 2003 or 2004. This summer has been even worse. The
surface area covered by sea ice was at a record monthly minimum for each
of the summer months - June, July and now August.

Scientists analysing the latest satellite data for September - the
traditional minimum extent for each summer - are preparing to announce a
significant shift in the stability of the Arctic sea ice, the northern
hemisphere's major "heat sink" that moderates climatic extremes.

"The changes we've seen in the Arctic over the past few decades are
nothing short of remarkable," said Mark Serreze, one of the scientists at
the Snow and Ice Data Centre who monitor Arctic sea ice.

Scientists at the data centre are bracing themselves for the 2005 annual
minimum, which is expected to be reached in mid-September, when anoth  [ send green star]
 September 16, 2005 10:53 AM

when another
record loss is forecast. A major announcement is scheduled for 20
September. "It looks like we're going to exceed it or be real close one
way or the other. It is probably going to be at least as comparable to
September 2002," Dr Serreze said.

"This will be four Septembers in a row that we've seen a downward trend.
The feeling is we are reaching a tipping point or threshold beyond which
sea ice will not recover."

The extent of the sea ice in September is the most valuable indicator of
its health. This year's record melt means that more of the long-term ice
formed over many winters - so called multi-year ice - has disappeared than
at any time in recorded history.

Sea ice floats on the surface of the Arctic Ocean and its neighbouring
seas and normally covers an area of some 7 million square kilometres (2.4
million square miles) during September - about the size of Australia.
However, in September 2002, this dwindled to about 2 million square miles
- 16 per cent below average.

Sea ice data for August closely mirrors that for September and last
month's record low - 18.2 per cent below the monthly average - strongly
suggests that this September will see the smallest coverage of Arctic sea
ice ever recorded.

As more and more sea ice is lost during the summer, greater expanses of
open ocean are exposed to the sun which increases the rate at which heat
is absorbed in the Arctic region, Dr Serreze said.

Sea ice reflects up to 80 per cent of sunlight hitting it but this "albedo
effect" is mostly lost when the sea is uncovered. "We've exposed all this
dark ocean to the sun's heat so that the overall heat content increases,"
he explained.

Current computer models suggest that the Arctic will be entirely ice-free
during summer by the year 2070 but some scientists now believe that even
this dire prediction may be over-optimistic, said Professor Peter Wadhams,
an Arctic ice specialist at Cambridge University.

"When the ice becomes so thin it breaks up mechanically rather than
thermodynamically. So these predictions may well be on the over-optimistic
side," he said.

As the sea ice melts, and more of the sun's energy is absorbed by the
exposed ocean, a positive feedback is created leading to the loss of yet
more ice, Professor Wadhams said.

"If anything we may be underestimating the dangers. The computer models
may not take into account collaborative positive feedback," he said.

Sea ice keeps a cap on frigid water, keeping it cold and protecting it
from heating up. Losing the sea ice of the Arctic is likely to have major
repercussions for the climate, he said. "There could be dramatic changes
to the climate of the northern region due to the creation of a vast
expanse of open water where there was once effectively land," Professor
Wadhams said. "You're essentially changing land into ocean and the
creation of a huge area of open ocean where there was once land will have
a very big impact on other climate parameters," he said.
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