July 2006 - The 2006 U.S. CLIVAR Summit took place this year in Breckenridge, Colorado 26-28 July. Agendas and panel reports are online.
The MJO Working Group presentations from their meeting 24-25 July 2006 in Breckinridge, CO are online.
January 2006 - The January 2006 Bulletin of the American Meteorological Society has an article on the NAME Field Campaign of 2004 and its modeling strategy. A future special issue of the Journal of Climate will focus on NAME as well.
The U.S. CLIVAR hosted a Town Hall Meeting at the AMS Annual Meeting in Atlanta, Georgia on Tuesday, 31 January. Presentations are now online.
International CLIVAR is seeking a Staff Scientist. Click here for the complete job description.
CLIMATE: New study 'closes loop' between warming and storm strength, authors
say
Lauren Morello, Greenwire reporter
Rising ocean temperatures in areas where hurricanes form are likely a result
of global warming caused by greenhouse gas emissions, according to a study
released yesterday.
The new research should "close the loop" on an ongoing debate over the causes of an increase in the overall intensity of hurricanes in recent years, said Tom Wigley, an author of the study and a senior scientist at the National Center for Atmospheric Research in Boulder, Colo.
Using 22 different climate models, Wigley and his co-authors -- 18 authors from spanning 10 research centers -- analyzed changes in sea surface temperature recorded between 1906 and 2005.
After examining several factors known to influence hurricane formation and strength, researchers concluded there is an 84 percent chance that human-induced factors -- largely greenhouse gas emissions -- are the driving force behind increasingly intense storms.
The study is the first to focus on conditions in areas of the Atlantic and Pacific oceans that serve as breeding grounds for most hurricanes.
"During this past year, there really have been major advances in the science of climate change and global warming," said Robert Corell, a senior policy fellow with the American Meteorological Society who was not involved with the new research. "We've now learned that the human-induced build-up of greenhouse gases in the atmosphere appear to be the primary driving force for increased hurricane activity."
Parsing the relative influence of climate change on hurricane trends, study co-author Greg Holland -- also a UCAR climatologist -- said global warming likely accounts for about 70 percent of the current storm activity, with natural variability contributing 30 percent.
The new paper -- which is set for publication this week in the online version of Proceedings of the National Academy of Sciences -- is the latest attempt to settle a debate that gained steam last fall. As hurricanes Katrina and Rita pummeled areas along the Gulf of Mexico, two prominent scientific journals published papers that argued rising sea surface temperatures have helped produce harsher hurricanes.
Backlash from government forecasters
Those studies -- one by MIT climatologist Kerry Emanuel, another by researchers
at Georgia Tech -- prompted swift disagreement from government forecasters
and others who have instead pinned the above-average storm activity over
the last decade or so on a natural weather pattern, the Atlantic Multidecadal
Oscillation (AMO).
"I think it's fair to say that there is no one who is arguing that over the past decade we have had a substantial increase" in hurricane frequency and intensity, said Holland. "The debate that has occurred is whether that is due to natural variation or climate. The current science is that it's actually a bit of both."
One of the most prominent critics of the attempt to link global warming to storm strength is NOAA scientist Chris Landsea, who has argued that flaws in older storm data have skewed research.
But in a briefing last week with reporters, Emanuel of MIT said Landsea is promoting an outdated argument that is refuted by the new paper.
"Chris Landsea is clinging to something, part of which I derived myself, that said an increase in sea surface temperature of 1 degree Celsius would increase windspeeds by 7 or 8 miles per hour," Emanuel said. "But that earlier theory did not grapple with the indirect effects of sea surface temperatures," which the new research persuasively links to global warming, he added.
CLIMATE: New study tries to 'nail down link' between sea temps, hurricanes
Lauren Morello, E&ENews PM reporter
Scientists who published a controversial paper last fall linking climate change
to increasingly powerful hurricanes released a new study today that its author
said "nails down the link" between sea surface temperatures and storm
strength.
"In terms of the long-term trend, it's really the sea surface temperature," said Judith Curry of Georgia Tech. "It's a complex subject -- there are no easy answers -- but I think we've really firmed up the link."
The report provides "extra evidence" linking ocean temperatures and storm intensity, said Kevin Trenberth, who heads the Climate Analysis Section at the National Center for Atmospheric Research.
"I think it's a great study," said Jay Gulledge, a senior research fellow with the Pew Center of Global Climate Change. "It takes a much more quantitative look at the relationships between hurricane intensity and environmental parameters than what's been done before."
The new research, published online in the journal Science Express, builds on earlier work by Curry and co-authors at Georgia Tech and the National Center for Atmospheric Research.
In a paper published last September, just weeks after Hurricane Katrina battered the Gulf Coast, the group concluded that the number of Category 4 and 5 hurricanes worldwide has nearly doubled in 35 years, even as the total number of hurricanes remained relatively steady. The scientists suggested the rise in severe storms is related to increasing sea surface temperatures. Since the 1970s, oceans have warmed by between 0.5 and 1 degree Fahrenheit during hurricane seasons.
Weeks earlier, MIT climatologist Kerry Emanuel published a related paper that found the destructive power of Atlantic hurricanes has more than doubled over the last 30 years, with the rise in sea surface temperatures partly responsible (Greenwire, Sept. 16, 2005).
Together, the two studies prompted vocal disagreement from prominent meteorologists, including the federal government's top hurricane forecaster. In several appearances before congressional committees last fall, National Hurricane Center director Max Mayfield said the recent surge in strong hurricanes is the result of natural weather cycles (E&ENews PM, Sept. 21, 2005).
New study digs deeper into historical records
The new study by Curry and her colleagues drills down even further into historical
hurricane records, attempting to isolate the relative influence of several
variables on storm strength. Along with sea surface temperature, Curry and
her colleagues examined wind shear, humidity in the lower atmosphere, and
zonal stretching deformation -- how likely winds are to rotate in cyclonic
fashion.
The scientists included storm data collected from 1970 to 2004 in six ocean basins, including the North Atlantic, Pacific and Indian oceans.
Applying tenets of information theory, rather than traditional statistical analysis, the researchers concluded that only sea surface temperature was the major driver for hurricane strength over the 35-year period included in the study.
The other factors, including wind shear, can influence the strength of individual storms or hurricane seasons, but their influence does not extend over decades, Curry said.
'Time will tell'
But the new work is not likely to end the fierce debate over the link between
ocean temperatures and hurricane strength, experts said.
William Gray of Colorado State University, one of the nation's most prominent hurricane forecasters and perhaps the most vocal critic of the earlier papers by Curry and Emanuel, said he had not seen the new study.
Still, Gray's ongoing work on the same subject leaves him certain that the new paper "is not correct, like the previous paper by Webster, Holland and Curry," he said. "I'm sure we will find problems with this paper, too."
For his part, Trenberth said that while he does not disagree with the paper's conclusions, "I do have some reservations," mainly to do with the quality of water vapor data sets Curry and her colleagues used.
The time frame of the study could also raise questions, he said: "The paper deals only with the 1970-2004 period, where we have satellite data, so there will no doubt continue to be criticism because in the North Atlantic, there was a very active period that occurred prior [to the studied timeframe] that is not part of the study."
And Jim Elsner, a professor in Florida State University's geography department, said applying information theory to the hurricane debate was "overkill.
"I don't think they needed such an elaborate method," he said. "They seem to be getting at the answer using a method that is probably not the right one, but their answers are in my opinion correct."
But Gulledge said the information theory approach was "a nice method" that "comes off a lot more complicated than it looks." He added: "If there are caveats, they probably have more to do with the [quality of] data itself than the analysis."
For her part, Curry said she and her colleagues' main hope is that the paper refocuses the debate over hurricane strength.
"Whether we're right or we're wrong, we believe that time will tell," she said. But in the meantime, Curry added, "We're providing a new look, a new perspective to this debate."
Go to E&ETV to watch OnPoint's interview with Georgia Tech professor Judith Curry as she explains her recent hurricane study and goes after some of the critics of her research.
WCRP ppt1
WCRP ppt2
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