Hot Air falsely claims new study says “hurricane strength has little to do with global warming”

Morrissey claims study “concludes that hurricane strength has little to do with global warming” and “nothing to do with AGW or carbon emissions.” From a March 1 Hot Air post by Ed Morrissey:

In the aftermath of Hurricanes Katrina and Rita in 2005, anthropogenic global warming (AGW) activists insisted that the stronger storm systems resulted from the build-up of carbon dioxide in the atmosphere, making hurricanes increasingly more severe. These claims made their way into the UN's IPCC report and have been a staple of AGW arguments for immediate and drastic action to limit energy production as part of the “settled science” attempt to shut down debate. Unfortunately for the hysterics, new peer-reviewed research published in Nature Geoscience concludes that hurricane strength has little to do with global warming.

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At the very least, the scientific research showing that hurricane strength cycles have nothing to do with AGW or carbon emissions is yet another reason to dismiss the highly-politicized 2007 report and the blatherings of politicians using it to seize control of the private energy sector. About the only reliable information left in the IPCC report is the page numbers.

In fact, study says “greenhouse warming” will increase hurricane “intensity” while decreasing hurricane “frequency”

Study in Nature Geoscience says models project increases in hurricane intensity due to greenhouse warming. The study (subscription required) cited by Morrissey, which was authored by 10 climate experts, states that “greenhouse warming” will cause an increase in tropical cyclone (hurricane) intensity but a decrease in tropical cyclone frequency:

[F]uture projections based on theory and high-resolution dynamical models consistently indicate that greenhouse warming will cause the globally averaged intensity of tropical cyclones to shift towards stronger storms, with intensity increases of 2-11% by 2100. Existing modelling studies also consistently project decreases in the globally averaged frequency of tropical cyclones, by 6-34%. Balanced against this, higher resolution modelling studies typically project substantial increases in the frequency of the most intense cyclones, and increases of the order of 20% in the precipitation rate within 100|[nbsp]|km of the storm centre.

IPCC report also said “it is likely that future tropical cyclones ... will become more intense.” From the IPCC's 2007 Synthesis Report:

Based on a range of models, it is likely that future tropical cyclones (typhoons and hurricanes) will become more intense, with larger peak wind speeds and more heavy precipitation associated with ongoing increases of tropical sea surface temperatures. [emphasis in original]

Hot Air forwards falsehood that IPCC said global warming “caused an increase in the number of tropical storms”

Morrissey quotes London Times claim that IPCC said “greenhouse gas emissions have caused an increase in the number of tropical storms.” From Morrissey's post:

Unfortunately for the hysterics, new peer-reviewed research published in Nature Geoscience concludes that hurricane strength has little to do with global warming:

Research by hurricane scientists may force the UN's climate panel to reconsider its claims that greenhouse gas emissions have caused an increase in the number of tropical storms. ...

However, the latest research, just published in Nature Geoscience, paints a very different picture.

It suggests that the rise in hurricane frequency since 1995 was just part of a natural cycle, and that several similar previous increases have been recorded, each followed by a decline.

In fact, IPCC said “there is no clear trend” in the “numbers of tropical cyclones”

IPCC 2007 report did not say greenhouse gas emissions have increased “the number of tropical storms.” The IPCC's Fourth Assessment Report stated, “There is no clear trend in the annual numbers of tropical cyclones.”

With respect to trends in hurricane intensity, the report stated that "[t]here is observational evidence for an increase in intense tropical cyclone activity in the North Atlantic since about 1970, correlated with increases of tropical sea surface temperatures. There are also suggestions of increased intense tropical cyclone activity in some other regions where concerns over data quality are greater." The IPCC's Working Group 1 stated that this increase in tropical cyclone intensity in some regions since 1970 was “more likely than not” (greater than 50 percent chance) influenced by human activity. The report further notes: “Magnitude of anthropogenic contributions not assessed. Attribution for these phenomena based on expert judgement rather than formal attribution studies.”

Hot Air, NewsBusters falsely claim new study undermines IPCC credibility

Morrissey: Study is “yet another reason to dismiss the highly-politicized 2007 [IPCC] report.” Misrepresenting the Nature Geoscience study, Morrissey wrote in his post: “At the very least, the scientific research showing that hurricane strength cycles have nothing to do with AGW or carbon emissions is yet another reason to dismiss the highly-politicized 2007 report and the blatherings of politicians using it to seize control of the private energy sector.” He added, “About the only reliable information left in the IPCC report is the page numbers.”

NewsBusters: Study is “another serious crack in the claims made by the United Nations Intergovernmental Panel on Climate Change.” In a March 1 NewsBusters post, Noel Sheppard stated of the Nature Geoscience study, “These revelations represent another serious crack in the claims made by the United Nations Intergovernmental Panel on Climate Change, and therefore seem quite unlikely to be reported by American media that have been largely ignoring all the errors that have been found recently in key IPCC documents.”

In fact, study's author said IPCC gave “an accurate summary of science that existed at that point”

AP: Study author said IPCC provided “an accurate summary of science that existed at that point.” While the Nature Geoscience study and the IPCC report agree that global warming will likely increase hurricane intensity in the future, they differ on whether human-caused warming has already changed hurricane activity in the past. The Associated Press reported on February 21 that the authors of the new study attribute this difference to the fact that “recent research has changed” since the IPCC report was compiled:

In 2007, the authoritative Intergovernmental Panel on Climate Change said it was “more likely than not” that man-made greenhouse gases had already altered storm activity, but the authors of the new paper said more recent evidence muddies the issue.

“The evidence is not strong enough that we could make some kind of statement” along those lines, Knutson said. It doesn't mean the IPCC report was wrong; it was just based on science done by 2006 and recent research has changed a bit, said Knutson and the other researchers.

Lately, the IPCC series of reports on warming has been criticized for errors. Emanuel said the international climate panel gave “an accurate summary of science that existed at that point.”