The recent Proceedings of the National Academy of Sciences (PNAS) paper 'Projected Atlantic hurricane surge threat from rising temperatures' has drawn coverage from at least three dozen media outlets, including US News & World Report , USA Today , Reuters, and MSNBC.
Some of the coverage has reached for the tone adopted by the headline and subheads in the UK's Daily Mail:
Hurricanes as big as Katrina will become 10 TIMES more frequent with just two degrees of global warming, study warns
* Two degrees celsius warming is the 'safe limit' set by climate scientists
* Storms as severe as the 2005 cyclone could happen once every two years
* Katrina killed 1,836 and left millions homeless
In contrast to that third subhead, US News emphasized the infrastructure problems that amplified Katrina's New Orleans destructiveness.
Aslak Grinsted, of the Center for Ice and Climate at the Niels Bohr Institute at the University of Copenhagen, served as the PNAS paper's lead author. The blog Climate Progress, acclaimed in the past by New York Times columnist Tom Friedman, reprinted a posting from the institute conveying Grinsted's views. Here's the lead paragraph:
By examining the frequency of extreme storm surges in the past, previous research has shown that there was an increasing tendency for storm hurricane surges when the climate was warmer. But how much worse will it get as temperatures rise in the future? How many extreme storm surges like that from Hurricane Katrina, which hit the U.S. coast in 2005, will there be as a result of global warming? New research from the Niels Bohr Institute show that there will be a tenfold increase in frequency if the climate becomes two degrees Celsius warmer.
Grinsted says that his study used 'temperatures from all around the world and combine[d] them into a single model.' Here's the PNAS abstract:
Detection and attribution of past changes in cyclone activity are hampered by biased cyclone records due to changes in observational capabilities. Here, we relate a homogeneous record of Atlantic tropical cyclone activity based on storm surge statistics from tide gauges to changes in global temperature patterns. We examine 10 competing hypotheses using nonstationary generalized extreme value analysis with different predictors (North Atlantic Oscillation, Southern Oscillation, Pacific Decadal Oscillation, Sahel rainfall, Quasi-Biennial Oscillation, radiative forcing, Main Development Region temperatures and its anomaly, global temperatures, and gridded temperatures). We find that gridded temperatures, Main Development Region, and global average temperature explain the observations best. The most extreme events are especially sensitive to temperature changes, and we estimate a doubling of Katrina magnitude events associated with the warming over the 20th century. The increased risk depends on the spatial distribution of the temperature rise with highest sensitivity from tropical Atlantic, Central America, and the Indian Ocean. Statistically downscaling 21st century warming patterns from six climate models results in a twofold to sevenfold increase in the frequency of Katrina magnitude events for a 1 °C rise in global temperature (using BNU-ESM, BCC-CSM-1.1, CanESM2, HadGEM2-ES, INM-CM4, and NorESM1-M).
The media coverage generally emphasizes the issue of attribution, the degree to which specific weather events can be linked to human-caused climate disruption.
This lead paragraph from MSNBC illustrates the emphasis:
Shortly after Superstorm Sandy pulverized the American Northeast, New York Governor Andrew Cuomo told reporters, 'There's a frequency in these extreme weather conditions, it's getting worse, it's getting worse all over the globe, getting worse all over the country, and I think we have to accept the reality.' Now, yet another study suggests he might be right.
US News used the subhead 'A Danish scientist says we may have crossed a threshold where super storms are caused by climate change.' That piece quoted Grinsted: 'Whenever we're asked whether Katrina or Sandy was caused by global warming, we have to give the standard answer that no single event can be attributed to warming. Well now, the odds have changed sufficiently and it's misleading to people to trot out the standard answer.'
In at least one case, scientific skepticism found its way into the coverage: USA Today quoted Georgia Tech climatologist Judith Curry, who called the paper 'very misleading.'
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Steven T. Corneliussen, a media analyst for the American Institute of Physics, monitors three national newspapers, the weeklies Nature and Science, and occasionally other publications. He has published op-eds in the Washington Post and other newspapers, has written for NASA's history program, and is a science writer at a particle-accelerator laboratory.
