On September 7 we tuned in to a press teleconference in which scientists Richard Somerville, Kevin Trenberth, Gerald Meehl, and Jeff Masters talked about the link between climate change and extreme weather events with reporters from the New York Times, ABC and NBC News, USA Today, and the online publications Greenwire and Energy Daily.
Post by Katherine O’Konski
The full audio recording of the press conference, along with a summary of the latest science on the subject, can be downloaded here.
The telecon, hosted by Climate Communication, included moderator Dr. Richard Somerville, from the Scripps Institution of Oceanography at the University of California, San Diego; Dr. Kevin Trenberth and Dr. Jerry Meehl, both from the National Center for Atmospheric Research in Boulder; and Dr. Jeff Masters, co-founder and Director of Meteorology at Weather Underground.
From the heavy snowstorms, droughts, floods, wildfires, and tornado outbreaks in the U.S. to the flooding in Pakistan, Australia, and Columbia, to the drought, heatwaves, and wildfires in Russia, the world has seen a plethora of extreme weather events in the past few years. The speakers drew a connection between global climatic disruption and the frequency and intensity of weather extremes. “We are changing the environment in which natural extremes occur,” Dr. Somerville pointed out. “This may become the new normal.”
Dr. Meehl stressed that even small changes in average global temperatures can produce noticeable changes in weather extremes. “We are shifting the odds toward more heat extremes and fewer cold extremes,” he said. In 2011 so far, the ratio is 3 record high temperatures for every record low temperature.
As climate is by nature a statistical phenomenon, we can’t say precisely if one event is directly attributable to global warming, but we can say that it (and the humans that caused it) had a significant impact because all weather now develops in a different environment than before.
Think of it like this Dr. Meehl said: Barry Bonds had a certain average level of home run production in his baseball career before he started allegedly taking steroids. Once he started taking performance enhancers, his home run production increased, and he set the single season record for home runs in 2001. Now he holds the all-time record for the most home runs. If we watched Bonds hit any one of these home runs, would we be able to say that it was directly caused by his steroid use? “No, that’s impossible. But the odds of him hitting one are much higher; his base state has changed.”
So cimate change has caused a similar shift of the odds in the atmosphere that will cause more extreme events to occur than if no such alteration existed. But all of this isn’t to say that extreme events occur only because of climate change. Climate change is increasing the frequency and intensity of extreme events, not their presence in the first place.
Indeed, the difference between these two concepts is a common climate denialist argument. And as Greenwire’s reporter noted, many farmers attribute the frequent droughts to a cyclical pattern within the climate system, rather than being caused by emissions of greenhouse gases. They “are of course correct, there have been lots of droughts,” Dr. Meehl explained. “Droughts are created by the system itself, but we have shifted the odds to make them more frequent and severe.” He also indicated that different causes of the droughts should be considered; the 1930s in the U.S. were a disaster with land-management practices. Now we have better land-use management, but even more severe droughts.
It’s equally important to consider the cost of extreme weather events. The cost of U.S. weather-disaster damages in 2011 alone has climed past $35 billion, according to NOAA estimates. So, as Dr. Trenberth pointed out, although the “direct impact of the Greenhouse effect is small on a day-to-day basis, it affects us through the cumulative effects” – not only through an altered climate system, but through the cost of damages to human society.
To conclude the conference, all four scientists stressed that without greenhouse gas emissions reduction, we can only expect the severity and frequency of extreme weather events to worsen. Dr. Somerville said, “Climate change is happening now; man can reduce the severity if we limit the global emissions of heat trapping gasses, but it must happen soon. Reductions must be large, and they must be global. These are no longer predictions of computer models, but observations of the real climate system changing.”