Extreme weather blown away from unexpected direction

Comment Allegations of a "surge" in "extreme" weather events has been quashed by a surprising source - the Intergovernmental Panel on Climate Change (IPCC).

"There is medium evidence and high agreement that long-term trends in normalized losses have not been attributed to natural or anthropogenic climate change," writes the IPCC in its new Special Report on Extremes (SREX) published today.

"The statement about the absence of trends in impacts attributable to natural or anthropogenic climate change holds for tropical and extratropical storms and tornados," the authors conclude, adding for good measure that "absence of an attributable climate change signal in losses also holds for flood losses".

Roger Pielke Jr, a professor at the Center for Science and Technology Policy Research at the University of Colorado Boulder, and a blogger who aligns himself with the "debate is over" camp, welcomed the IPCC report.

"Anytime that you read claims that invoke disasters loss trends as an indication of human-caused climate change… you can simply call 'bullshit' and point to the IPCC SREX report," said Prof Pielke. He adds: "Kudos to the IPCC - they have gotten the issue just about right, where 'right' means that the report accurately reflects the academic literature on this topic."

One "surge" that is not disputed is the recent rapid increase in reports attempting to link extreme weather to a human influence. Coumou and Rahmstorf produced one attempt last week; Lubchenco and Karl another. And with remarkable coincidence, the BBC chipped in with a Horizon documentary on "strange patterns of severe weather".

Whether there is an increase in extreme weather is disputed; more hurricanes are recorded, including many that would never have been recorded before. Hurricane energy is a good proxy for increased energy in the climate, but this shows no increase for 15 years.

Global Hurricane Energy since 1974: not so weird

Pielke suggests a reason for this amazing surge. With concern for the climate change waning in the few English-speaking countries in which it ever captured the imagination, "extreme" weather reports are useful as a propaganda tool.

"The siren song of linking disasters to human-caused climate change exerts a strong pull for activists in all settings," he said.

Without strong scientific evidence, the use of "extreme" or "strange" weather to manipulate support for contentious political programmes relies on enduring and ancient superstitions. ®

Link to the report

SREX