Increased flooding driven by climate change: study

By Agence France-Presse
Wednesday, February 16, 2011 20:58 EDT
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PARIS – Global warming driven by human activity boosted the intensity of rain, snow and consequent flooding in the northern hemisphere over the last half of the 20th century, research released Wednesday has shown.

Two studies, both published in Nature, are among the first to draw a straight line between climate change and its impact on potentially deadly and damaging extreme weather events.

Australia, Sri Lanka, Brazil and Pakistan have all been recently ravaged by massive flooding, raising questions as to whether global warming was at least partly to blame.

Computer models have long predicted that the observed rise in atmospheric greenhouse gases would magnify episodes of diluvian rainfall.

But up to now, the link has been largely theoretical.

“This paper provides the first specific evidence that this is indeed the case,” said Francis Zwiers, a researcher at the University of Victoria in Canada and a co-author of one of the studies.

“Humans influence the intensity of precipitation extremes,” he told journalists in a telephone press conference.

Data gathered between 1951 and 2000 from across Europe, Asia and North America showed that, on average, the most extreme 24-hour precipitation event in a given year — whether rain, snow or sleet — increased in intensity over the last 50 years of the 20th century.

When this measurable spike was compared with changes simulated by climate models, the fingerprint of human influence on Earth’s weather patterns was unmistakable, Zwiers said.

“The observed change cannot be explained by natural, internal fluctuations of the climate system alone.”

The main driver was simply more water in the air. “In a warmer world the atmosphere has greater moisture-holding capacity,” he explained.

That doesn’t necessarily mean that in a place where it doesn’t rain very much precipitation will increase, he added. Indeed, some spots on Earth are likely to be drier.

But it does mean that when a hurricane or snowstorm does occur, there is more water available.

Why did it take so long for scientists to begin to make solid connections between global warming and extreme weather events?

One reason is that only in recent decades has the accumulated influx of heat-trapping gases become more obvious. “We are finding it easier and easier to detect that signal in observations,” Zwiers said.

Progress has also been hampered by the lack of reliable, long-term data, and the sheer computer power needed to test ever-more complex computer models against reality.

In the second study — which sought to tease out the impact of global warming on England’s wettest autumn on record, in 2000 — scientists led by Myles Allen of the University of Oxford tapped into the power of Internet-based social networks to overcome this last constraint.

The researchers compared two climate models, one based on detailed historical weather data and the other on a “parallel” autumn 2000 simulating conditions had no greenhouse gases been emitted in the 20th century.

Global warming likely doubled the odds that such an event would occur, they found.

“To really pin down the difference between these two worlds, we needed to repeat the simulation thousands of times,” explained lead author Pardeep Pall, who initiated the project as a graduate student in 2003.

“We asked members of the public across the world to run the simulations for us on their own personal computers using their idle time.”

Based on the results of the study, Britain national climate and weather office is developing tools to measure the human influence on future extreme weather events.

“This kind of study is going to allow us to quantify how climate change is affecting people now so it ceases to be some hypothetical projection of the future,” said Allen.

The tool could also be useful in legitimating requests from developing countries seeking to tap into the hundreds of billions of dollars earmarked for climate adaptation, he said.

Members of the public interested in lending computing power can find information at climateprediction.net, which is currently fueled by 50,000 to 60,000 personal computers at any given time.

Agence France-Presse
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  • Anonymous

    And when the Global Warming deniers get flooded they will beg for FEMA and Obama to help them even though they say they hate government.
    Hypocrites and morons.

  • http://pulse.yahoo.com/_WHD5BGNXCZNRYLTTFTQXBZMLQI Hayduke

    “The observed change cannot be explained by natural, internal fluctuations of the climate system alone.”

    Why not? Says who? By what evidence? The fact that global average surface temperatures are increasing slightly does not mean, ipso facto, that it is caused by humans.

  • Guest

    not me.

  • Guest

    I love this crap, it’s like gun control weirdos. They cite studies that are deliberately designed to minimize the crime and crime related cost reduction of allowing free and open access to guns specifically concealed carry. Like AGW advocates they seem to be able to get anything published in the press without citing anything at all that is relevant or compelling. The stats that they DO publish are flawed at best, nefarious at worse.

  • Anonymous

    Here’s something else you might consider because according to you and your John Lott theory of gun ownership when you have a gun you are safe. Explain what went wrong here, please!


  • Guest

    Dude, You’re never safe… not even with a Einstein avatar. Bad things happen and a gun won’t necessarily save you – but then again it could. And if you bothered to read Lott or any of the other hundreds of books and studies out there you’ll begin to see the larger picture – that the second amendment isn’t only a right that predates the constitution – it’s also common sense. Citing one story or even a thousand doesn’t contradict the whole. I recommend that you buy a gun, then you’ll have the responsibility of learning how it works, all the laws that we must adhere to, safety concerns and you’ll come in contact with hundreds and hundreds of gun owners.

    In respect to the above issue – my contentions still remain the same. Climategate proved what we knew all along. This is a political issue – not meteorological one.

  • http://www.facebook.com/profile.php?id=1046573071 Matt Mosley

    Man-made Global Warming. HA! 30-years ago it was global cooling. Yes Climate Change exists, it’s called the seasons. And like the year, decades also have warmer and colder times, just look at history.

    When you’ve looked at history, look at where the money you pay in “Climate Taxes” goes, because it’s not to deducing anything, just increasing the bank accounts of multi-billionaires.

    And sorry if you wanna bitch about what I say, I am a liberal and you should Google the “Oregon Petition”.

  • Anonymous

    Hmmmm, I have been under alot of snow all winter- global temps change as they have done and always will- before man and after man. The term “Climate Change” is so weak… We all want a cleaner Earth, we just differ on whether killing the economy is worth satisfying a false idol.

  • Roberthe

    Of course you’ve been under snow: it’s winter. Many people who don’t accept the possibility of climate change consider snow in winter to be validation for their denial. It is almost as if they think in February they should be outside working on their tans rather than grumbling about having to shovel their sidewalks. That’s not what it’s about. The question is whether or not the planet as a whole is warming up, and most indications are that it is. Even this winter in the Northern Hemisphere, and I admit that parts have been hammered by atrocious conditions, there are indications that what you are experiencing is being driven by warming conditions in the Arctic. January posted the lowest extent of ice since records started being kept, 50,000 square kilometers less than the previous record, but that is not as impressive as the 1.2 million kilometers less ice compared to the 1979-2000 average for January (records started being kept in 1979). Temperatures over the Arctic were 4° to 11° F warmer than the January average as well. This has the tendency to push cold weather south (lucky us).

    Perhaps it’s all natural variability as you suggest. I certainly can’t prove otherwise, but then I’m not a climatologist. However, looking around the world I see increased weather-driven catastrophes. Highlights for 2010 would have to include the devastating heat wave in eastern Europe, the hottest ever in Russia, with its fires, its doubled death rate, and the destruction of 25% of its grain crops, the incredible rainfall in the Swat Valley (200 inches in 60 hours!) and the inundation of 20% of Pakistan (some of which is still under water), coupled with severe droughts in the Amazon Basin and sub-Saharan Africa. These are only a smattering of the devastation caused by climate last year. Admittedly it happened this month but I’d like to offer Severe Tropical Cyclone Yasi, perhaps the strongest cyclone ever to hit Australia (larger than Katrina), for consideration. All in all, it’s been a busy year. If you’ve been paying attention you’ll notice that there have been several such years recently. Climatologists study these phenomena. 97% of them have reason to believe the increase in extreme weather is caused, at least in part, by our altering of the atmosphere. Until I see significant evidence to the contrary I’m going to side with them.

  • Anonymous
  • Anonymous

    Looks like the deniers are out in force today.

  • Anonymous

    Slighty? if the average planet temp rises by 6 degrees then the planet will not be able to sustain life. If I remember correctly I think that the planet temp has risen by almost 1.5 degrees in the last 150 years. The other problem is that the rate by which it is increasing at a faster rate per year.

    By what evidence? By the evidence produced by the 98% of climatologist who are not having their research paid for by the executives who run the companies that are causing the pollution.

    Or do still believe that there is no link between cigarette smoke and cancer. Remember, the scientist sponsored by the tobacco companis stated that there is no link between the two.

  • Anonymous

    We are the majority now. The voodoo climate change science has be debunked completely

  • Anonymous


  • Roberthe

    Not too long ago the majority knew the Earth was flat and motionless at the center of the universe. Right now 40% of Americans do not believe in evolution; interestingly, 20% still believe the Earth is motionless at the center of the universe. This isn’t a beauty contest, this is a scientific debate. Your claim that climate change has been debunked is, at best, absurd. It certainly isn’t the belief of the overwhelming majority of scientists in the field, nor is it supported by the world’s scientific academies. In order to accept your premise you need to fabricate the most massive hoax ever perpetrated by the scientific community. In that there never has been a single hoax perpetrated by the world’s scientific community I put my trust in them rather than in the Heartland Institute and the other corporate guns-for-hire who have tried to convince us that smoking is good for us, or more recently that DDT and dioxin pose no harm to our health. Good luck, we’re all going to need it.

  • Anonymous

    A degree with “science” in the title does not make one an informed scientists — the Oregon petition is the political piece and was “supported” by an article that could not pass review in the scientific journals.

  • Anonymous

    Debunked by who in what scientific process — what is the flaw in the underlying physics? What is the flaw in all the underlying evidence that all points in the same direction? What, of all the studies that have determined that the usual drivers of a changing climate are not sufficient, or are even driving the oppposition way can you point to as flawed? You folks have to get your info from someplace beside the interenet.