Weather extremes linked to warming

2012-03-26 07:26

London - Extreme weather events over the past decade have increased and were "very likely" caused by man-made global warming, a study in the journal Nature Climate Change said on Sunday.

Scientists at Germany's Potsdam Institute for Climate Research used physics, statistical analysis and computer simulations to link extreme rainfall and heat waves to global warming. The link between warming and storms was less clear.

"It is very likely that several of the unprecedented extremes of the past decade would not have occurred without anthropogenic global warming," said the study.

The past decade was probably the warmest globally for at least a millennium. Last year was the eleventh hottest on record, the World Meteorological Organisation said on Friday.

Extreme weather events were devastating in their impacts and affected nearly all regions of the globe.

They included severe floods and record hot summers in Europe; a record number of tropical storms and hurricanes in the Atlantic in 2005; the hottest Russian summer since 1500 in 2010 and the worst flooding in Pakistan's history.

'Complex processes'

Last year alone, the US suffered 14 weather events which caused losses of over $1bn each.

The high amount of extremes is not normal, the study said.

Even between March 13 and 19 this year, historical heat records were exceeded in more than 1 000 places in North America.

For some types of extreme weather, there are physical reasons why they would increase in a warming climate. For example, if average temperature rises, then so will the number of heat records if all else remains equal, the study said.

Natural weather patterns like El Niño or La Niña can also cause highs in global temperature or increased precipitation which leads to floods.

"Single weather extremes are often related to regional processes, like a blocking high pressure system or natural phenomena like El Niño," said Stefan Rahmstorf, co-author of the study and chair of the institute's earth system analysis department.

"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."


Recent years have seen an exceptionally large number of record-breaking and destructive heat waves in many parts of the world and research suggests that many or even most of these would not have happened without global warming.

Currently, nearly twice as many record hot days as record cold days are being observed both in the US and Australia, the length of summer heat waves in western Europe has almost doubled and the frequency of hot days has almost tripled over the period from 1880 to 2005.

Extremely hot summers are now observed in about 10% of the global land area, compared with only about 0.1% - 0.2% for the period 1951 to 1980, the study said.

The link between storms and hurricanes and global warming is less conclusive but at least some of recent rainfall extremes can be attributed to human influences on the climate, it added.

  • Justin - 2012-03-26 08:48

    Global warming is just another smoke screen for mafia like crime boss tactics to extort money from taxpayers. How much more bull do we have to put up with before we say enough. Dang....

      Richard - 2012-03-26 09:02

      You'd think the media was bored of this fad by now... I know I am.

      Arthur - 2012-03-26 10:33

      I disagree Meme - yes Global warming and weather patterns are changing, but human impact is actually a very small percentage. The shifts are a natural cycle. Remember in the 80's when they said we were heading for an ice-age? I'm all for cleaning up the environment but I don't think fear-mongering is necessary - I also think "Carbon tax" is illegal and a farce. We're already taxed up to 45% on our salaries, 32% on our annual turnover, 14% on anything we buy, then there's sin tax, fuel levies, land levies, toll fees and now carbon tax. Just how much can you milk the cow? Pah-leez.

      Ernst - 2012-03-26 10:47

      @Hugh_Influence: You are just plain wrong. The climate reacts to whatever forces it to change at the time; humans are now the dominant forcing. Arguing that the climate changed before and so humans cant be responsible is like arguing that fires always started naturally, therefore man cant start fires.

      Ernst - 2012-03-26 10:56

      @Justin: Your comment is laughable. Do you know how much of your taxes go into subsidies for oil, coal and gas companies?

      Arthur - 2012-03-26 11:11

      @Ernst - I know there's scientific data to prove that human influence has increased from 0.27% to 0.39% (toughly 40%) in the last 100 years which is significant, however that only accounts for 3% - 5% of human contribution as apposed to the roughly 95% natural CO2. Explain why Al Gore pulled all his "data" - because he was wrong and alarmist. Again - don't get me wrong - I'm NOT saying that even the small 5% of human contribution is a good thing, or that we shouldn't clean up our act (recycle, plant trees, use cleaner energy etc) - I'm saying Carbon tax is rubbish and that there's no need for people to claim doom and gloom with threats of mega destruction in the near future. A 0.8% increase in temperature in 100 years isn't great news but it certainly won't wipe the planet out. I wonder how many heavy weather anomalies are influenced greatly by other factors - such as the magnetic shift in the poles?

      Ernst - 2012-03-26 11:20

      @Hugh_Influence: You know, what I cannot understand is whenever there is an argument on Global Warming, Al Gore's name always pops up. Al gore this and Al gore that, "church of Gore" etc. Al Gore is not an expert on climate science; he merely tries to convey the possible consequences of inaction. What people have to look at is not what Al Gore says but what the body of peer reviewed literature is saying. That is where you will find the most accurate answers. My point is: Forget Al Gore. You sound like a guy with an open mind. The following links I provide is to a website that uses peer reviewed research to debunk common climate myths. Perhaps you would be interested in checking it out.

      Arthur - 2012-03-26 11:44

      @ Ernst - just saw this which was a good read:

  • Arthur - 2012-03-26 11:28

    @ Ernst - was merely using Gore as a reference for "panic tactics" all too common in main stream media, not as a scientific reference (how gullible people can be). Thanks for the links, will have a read - funny enough I was just about to read to check up on my own facts. I'm quite happy to eliminate oil and coal emissions - happy days - and I see Swatch is investing in researching a Hydro / Oxygen vehicle which is long overdue. I'm against fear-mongering in all senses, either for or against the whole Greenhouse debate. I also don't think it's fair that the man on the street must bear the brunt of Carbon taxes when the government is largely responsible for funding the damage in the first place through (like you mentioned above) subsidies to oil and coal companies, but also the likes of Monsanto, dangerous chemical weapons and so on.

      Ernst - 2012-03-26 12:17

      @Hugh_Influence: Thanks alot. I will read the link you provided.

  • jody.beggs - 2012-03-26 13:10

    Its just a cycle , it'll warm up to the next ice age. Then cold for +- 10 000 years.

  • ludlowdj - 2012-03-27 11:12

    Meme, doing your own propaganda "spin doctoring" here. The study which has split the scientific community does not prove anything of the sort, and has only resulted in grown and educated men shouting and screaming at each other about who's more qualified than the other to make a statement. The temperature averages for the last 10 years have not changed, and the rate of ice cap melting has not increased in that period either.Area specific temperature fluctuations cannot ever be used as a gauge of changes like those you refer to in Cape Town. Total global averages are the only reliable measurement. As for carbon increases, the truth is that as the earth has developed over the years carbon levels have in fact dropped drastically, being estimated to have been over 900 time higher in the Jurassic period. Climate change is little more than a regular cycle that has existed since before man crawled out of the slime and will still be occurring long after man has ceased to exist. Although conservation and pollution prevention are desperately needed to ensure our future and the future of the planet as a whole, using global warming as the excuse is tantamount to fraud.

      Ernst - 2012-03-27 16:38

      @ludlowdj: True, the climate has always changed. The problem is that man is changing the atmospheric concentrations of greenhouse gasses at a tremendously fast rate. In the past, animals and plants had thousands of years to adapt. We are causing these changes in a matter of decades. "...being estimated to have been over 900 time higher in the Jurassic period." So you think its a good idea to go back to conditions that existed when the dinosuars were alive? I am sure that you will be the first to complain about food prices that start skyrocketing because not enough food can be grown to feed all of us.

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