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EcoAlert: New Evidence Links Earth's Extreme Weather to Human-Caused Global Warming



The past decade has been one of unprecedented weather extremes. Scientists of the Potsdam Institute for Climate Impact Research (PIK) in Germany argue that the high incidence of extremes is not merely accidental. From the many single events a pattern emerges. At least for extreme rainfall and heat waves the link with human-caused global warming is clear, the scientists show in a new analysis of scientific evidence in the journal Nature Climate Change. Less clear is the link between warming and storms, despite the observed increase in the intensity of hurricanes.

In 2011 alone, the US was hit by 14 extreme weather events which caused damages exceeding one billion dollars each – in several states the months of January to October were the wettest ever recorded. Japan also registered record rainfalls, while the Yangtze river basin in China suffered a record drought. Similar record-breaking events occurred also in previous years. In 2010, Western Russia experienced the hottest summer in centuries, while in Pakistan and Australia record-breaking amounts of rain fell. 2003 saw Europe´s hottest summer in at least half a millennium. And in 2002, the weather station of Zinnwald-Georgenfeld measured more rain in one day than ever before recorded anywhere in Germany – what followed was the worst flooding of the Elbe river for centuries.

"The question is whether these weather extremes are coincidental or a result of climate change," says Dim Coumou, lead author of the article. "Global warming can generally not be proven to cause individual extreme events – but in the sum of events the link to climate change becomes clear." This is what his analysis of data and published studies shows. "It is not a question of yes or no, but a question of probabilities," Coumou explains. The recent high incidence of weather records is no longer normal, he says.

"It´s like a game with loaded dice," says Coumou. "A six can appear every now and then, and you never know when it happens. But now it appears much more often, because we have changed the dice." The past week illustrates this: between March 13th and 19th alone, historical heat records were exceeded in more than a thousand places in North America.

The scientists base their analysis on three pillars: basic physics, statistical analysis and computer simulations. Elementary physical principles already suggest that a warming of the atmosphere leads to more extremes. For example, warm air can hold more moisture until it rains out. Secondly, clear statistical trends can be found in temperature and precipitation data, the scientists explain. And thirdly, detailed computer simulations also confirm the relation between warming and records in both temperature and precipitation.

With warmer ocean temperatures, tropical storms – called typhoons or hurricanes, depending on the region – should increase in intensity but not in number, according to the current state of knowledge.In the past decade, several record-breaking storms occurred, for example hurricane Wilma in 2004. But the dependencies are complex and not yet fully understood. The observed strong increase in the intensity of tropical storms in the North Atlantic between 1980 and 2005, for example, could be caused not just by surface warming but by a cooling of the upper atmosphere. Furthermore, there are questions about the precision and reliability of historic storm data.

Overall, cold extremes decrease with global warming, the scientists found. But this does not compensate for the increase in heat extremes.

"Single weather extremes are often related to regional processes, like a blocking high pressure system or natural phenomena like El Niño," says Stefan Rahmstorf, co-author of the article and chair of the Earth System Analysis department at PIK. "These are complex processes that we are investigating further. But now these processes unfold against the background of climatic warming. That can turn an extreme event into a record-breaking event."

Article: Coumou, D., Rahmstorf, S. (2012): A Decade of Weather Extremes. Nature Climate Change [DOI: 10.1038/NCLIMATE1452]

The Daily Galaxy via pik-potsdam.de

Image credit:With thanks to Markusram on Flickr.

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BS...... Does anybody acknowledge the Southern Atlantic Anamaly and global warming/sea level rise to warming? the scientist know about this drastically accelerating (weakeining magnetic field). They dont understand it so they ignore it from any of the climate warming Models....humans have zero impact on this. Hell, the hubble telescope has to be switched off when traveling over this thing. it's allowing more cosmic radiation to hit earth, the upper atmosphere etc... check it out.

I'm just a tad skeptical -- not that global warming is human-caused (there can be little doubt of that), but that it's as extreme as we're being told.

We just don't have meteorological records old enough to know if things actually are more severe now than at any other time in the past 5000 years. That's important, as we have not yet set a new record of average global temperature. My copy of Richard Muller's "Science for Future Presidents" is AWOL at the moment, but I as recall: fossil records indicate that the average global temperature was higher during the height of Roman and Egyptian civilizations than it is now.

The current speed of change is indeed alarming, and we do definitely need to change our behavior in terms of energy sources and habitat destruction, but we're not in quite the pickle that many are saying.

This guy in the article presents a widely incorrect belief of randomness. He says "A six can appear every now a ....". Randomness does NOT prohibit a six appearing many times in sucession. It merely means that six would appear about 1/6 of the time given a large enough sample.

by product of the small intestine of you know what

watched a documentary (open university) on global warming once.
they were at the spot where they take core samples of ice and store them so they can study climate change (the greatest history we have on the subject).

you know what they explained..the guys who do the work...who analyise the data...who spend there lives away from there family risking life and limb, freezing there arses off drilling popcicles for nothing but fun.

they said that there is not enough history there to provide enough evidence either way, as the changes occur over too great a period.

ive heard certain scientists, politicians, green folk, know it all's proclaiming this and that,,,stating that the evidence is being found in the ice.

as stated above...bullshit!

it's not possible, we have nooooo way on earth (literally) of telling if this is man-made or natural warming.

the only real facts are that the poles do switch and we are overdue (very slightly, but not drasticaly off schedule) for the next ice age.
we do pollute massively and its going to screw us up sooner or later.
these "extreme" and a great deal worse weather conditions ARE NORMAL for our planet, we just havent had any recent experience of it.

fed up of these arseholes quoting such rubbish.
they cannot tell one way or another.
it's scaremongering and political bullshit prodded on by the ever blinkered environmentalists.

I live in Northeast Ohio and over the last ten years I've watched the weather patterns change quite dramatically. It used to be that we had snow on the ground almost continuously from December to the middle or end of March now fall just turns into spring with almost no snow. The trees start budding at the end of January
and last week we could hear tree frog and American toad mating calls, they aren't supposed to do that until June.

This is going to continue to escelate an I wonder how long it will take until some of you can't ignore it anymore.

it's definatly changing, no doubts there, the uk winters are off by a month or more and a lot longer.

i just wish they'd stop confusing it with the effects of pollution when theres no evidence nor will there be for some 100,000 years that it is the overall cause.

not to mention the global pollution of the atmosphere by man has been dropping steadily since the 70's and is a whole load better than it was during and after the industrial revolution :\

I guess I missed the part where these guys link Earth's extreme weather to HUMAN caused global warming.

Since the early days of GW discussion I've tried to remain "on the fence" about studies because of the vast periods of the Earth's climate cycles. If something seems unusual over a 10 or even 100 year period, it's a speck on the geological timeline.

I absolutely want the research to continue though. Learning about climate cycles and how we may have an impact on climate (change) is important.

original comment from Rocky D. • (from) Trinity Western University
Climate has always changed. It is an historically and scientifically supported fact (through actual measurements) that the earth's climate naturally cycles from cooler to warmer and back again, and has been for eons. There are no "climate change deniers" on this planet, because all people believe climate has changed on the planet when faced with the facts. Everyone understands that climate changes, but why and how? The earth has warmed considerably from the Ice Age until now, even when no human beings were belching CO2 into the atmosphere for thousands of those years. There are those who understand that the earth's climate goes through natural cycles, and for the past 100 years or so has actually been quite stable in comparison to past change events. If anything, history shows us unequivocally that climate change (either wa...rming or cooling) will happen quite naturally no matter what people do. This has nothing to do with greed, ignorance and the like. It has everything to do with real, raw evidence and scientifically support facts. For those who understand the scientific method, they understand it is impossible to test the theory that human produced fluorocarbons are contributing to climate change. The oceans produce many times the amount of CO2 gas than humans do (scientific fact) and these oceans are the main contributor to climate change on the planet, not people. The first thing people are going to jump on me about is that I now think polluting the earth is okay. I don't. For the sake of clean air, water, and earth, let's make every effort to decrease pollution and stop ruining the planet and wasting resources. But for heaven sake, please quit using junk science to scare people into thinking that they caused the latest flooding in Thailand or Australia because they drive an SUV or use Aquanet. Let's reduce pollution for the sake of life on this planet -- for a better, cleaner, brighter future for our children and for every creature we share this planet with. We don't need the "climate change boogey man" to do that, do we?

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