Study: Climate Change Makes Extreme Floods & Storms More Likely

By Andrew Moseman | February 16, 2011 5:27 pm

One cannot look at a single storm, flood, or drought and say conclusively, “climate change caused that.” But what researchers are attempting to do lately is climate change risk assessment—figuring out how much more likely severe events may become as our world continues to warm up. Two new studies in Nature today try to do just that with heavy rains and flooding, saying definitively that warm temperatures make these events more likely.

More-localized weather extremes have been harder to attribute to climate change until now. “Climate models have improved a lot since ten years ago, when we basically couldn’t say anything about rainfall,” says Gabriele Hegerl, a climate researcher at the University of Edinburgh, UK. [Nature]

Hegerl and climate researcher Francis Zwiers were authors on study number one, a broad-based look at how much humans are contributing to intense precipitation events in the Northern Hemisphere. The simple physics of it makes sense: warmer air can hold more water. To show a link, however, the researchers pulled together a half-century of rainfall records, which they compared to the results of eight different climate models.

Richard Allan, a climate scientist at the University of Reading in England who was not part of the study, called the method employed by Zwiers “very rigorous.” He added, “There’s already been quite a bit of evidence showing that there has been an intensification of rainfall” events across the globe. But until now “there had not been a study that formally identified this human effect on precipitation extremes,” Zwiers said. “This paper provides specific scientific evidence that this is indeed the case.” [Washington Post]

The second study looked into a particular event—the major floods of 2000 in England and Wales, the worst in the U.K. since 1766—to try to determine how much climate change increased the risk of such an event. To do so, they needed to run a countless models to sort out the variables that could skew the findings. Thankfully, the team could turn to the crowdsourcing project, which, like the alien-hunting SETI@Home project, relies on ordinary people to volunteer their computers’ down time.

The team ran models simulating the real weather and, crucially, models of the region’s weather as it might have been in a world without human-produced greenhouse gases. The models were run thousands of times to enable the probability of the extreme floods to be determined in both scenarios, taking 40,000 years of computing time. Global warming was found to have most likely doubled the risk of the 2000 floods, but there is a one in 10 chance that the increased risk was as high as 700% or as low as 20%. [The Guardian]

Says study coauthor Myles Allen of Oxford University:

“Damaging weather events have always happened since well before humans had any substantial influence on climate,” says Allen. “This research allows us to quantify how rising greenhouse gas levels may be loading the dice in favor of certain events, such as the U.K. floods of 2000, and against other events.” [USA Today]

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Image: Wikimedia Commons

  • mememine69

    Journalists that covered the climate change mistake for the last 25 years of needless panic, have done to science and media, what abusive priests did to the Catholic Church. You lazy copy and paste clowns will sooner or later be charged with treason for leading us to a false war of climate variation and for condemning our children to a death by CO2. Meanwhile, the UN had allowed carbon trading to trump 3rd world fresh water relief, starvation rescue and 3rd world education for just over 25 years of climate control instead of needed population control. Call the courthouse and have theses news editors charged for perpetuating this needless panic and fear mongering.

  • nick

    Dear Meme, please to be making sense and cogent arguments, and not ridiculous statements like “journalists will be charged with treason” if you’d like someone to engage you in discussion in any sort of serious way. Thanks.

  • s

    agreed Nick, he’s a bit off the wall…but Mem does make a valid point about the idiocy of the UN. In that, Mem is correct. One has to look no further than Iran on the UN’s Human Right’s Committee.

    The problem with these “models” is that they are created with an inherent assumption….that global warming is real.

    The Sun is about to enter it’s next cyclical active period. Global Warming nazi’s are salivating at that prospect because they know the media won’t report that, or the correlation between the Sun and weather. They will only reprot on the gothic storms that are about to assail us.

    “Global warming is so stupid. Picture 2 guys standing around a huge bonfire. One guy lights a cigarette. The other guy pokes him in the ribs and says, “Hey buddy. Put that out…I’m too hot!”

    – Larry the Cable Guy

  • John Lerch

    I said a dozen years ago that when you crank up the gain on a feedback system, you are guaranteed to have overdrive oscillation. And since CO2 addition is a set point change in one loop of the control system, that translates into an effective infinite gain. Therefore, the likelihood that CO2 addition would not create global warming and not create wild weather swings is ZERO.
    The only question of relevance is: Is there enough compensatory cooling in the THEORETICAL global COOLING to offset the direst predictions of the FACT of GLobal Warming. Global warming is a FACT by virtue of being predicted a century before it was looked for–the first NOBEL PRIZE WINNER in chemistry predicted it in 1900!!!!!!!! (Phenomena predicted before detection are accorded the appellation of fact–like the results of the 1919 solar eclipse observations verifying General Relativity even though subsequently there are competing models with close to the same numbers.)

  • John Lerch

    I forgot to mention above that the solar cycle is of WAY TOO SMALL a magnitude to drive climate cycles BY ITSELF. Like the paradigm of a parametrically driven oscillator–a child pumping on a swing–it can only drive oscillators that already exist. And if those oscillators’ fundamental parameters are permanently changed, the oscillation will become easier if the parameters tend that way or harder if that way.


    As s Says says:
    “The problem with these “models” is that they are created with an inherent assumption….that global warming is real.”

    In the last 3,000 years, there was more storm activity in cold periods than in warm periods. An article in the International Journal of Climatology states that if global warming occurs some models show an increase in extreme events while other models show a decrease in extreme events. In the last 110 years there is no evidence of trends of extreme weather events in the winter season.

    A recent study by National Institute of Oceanography, Goa, scientists led by Dr. M.R. Ramesh Kumar, Senior Scientist, Physical Oceanography Division, and published in the Indian Journal of Geo-Marine Sciences, clearly indicates that warm sea surface temperatures alone are not sufficient for the initiation of convective systems over the Bay of Bengal.

    Disputing various press speculations there is no correlation between Arctic ice and Northern snow extent.

    From 1895/7 to 2007 there is 0.85 correlation of global temperature with oceanic oscillations; 0.57 with solar intensity fluctuations; and 0.43 correlation with CO2 concentration. From 1987 to 2007 there is a 0.02 correlation of global temperature with CO2 concentration.

    mrmrminr69 is correct.

  • bab

    The population of india ,pakistan and africa are increasing ,the war in north africa and middle east is severe ,every month one chemical plant or oil refinery exploded so how we can stop climate change? even poor and middle class people want more money and they dont care about climate change ,


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