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~QT~™ asked in EnvironmentGlobal Warming · 10 years ago

Are we beginning to witness the effects of global warming?

The extreme heat wave that hit Europe in the summer of 2003 had adverse social, economic and environmental effects. Total economic losses were estimated to exceed 13 billion euros (~US $16,640,000,000). Furthermore, there were 30,000 heat-related deaths throughout Europe.

It's likely that global warming contributed to this disaster. According to an analysis by United Kingdom-based climatologists, twentieth century warming has doubled the risk of such a heat wave:

Another study concluded that the frequency of extremely hot days has tripled over the last century and length of heat waves on the European continent has doubled:

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In 2006, another extreme heat wave struck Europe:

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This year, we're experiencing yet another severe heatwave:

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Global warming can explain the long-term increase in heat waves. However, it's impossible to determine the cause of a specific weather event (e.g. a heat wave).

Might global warming have contributed to these specific heat waves? What else may have caused these severe weather events?


@ linlyons

How am I "Cherry picking"?

As the IPCC concludes:

"It is very likely that cold days, cold nights and frosts have be- come less frequent over most land areas, while hot days and hot nights have become more frequent. It is likely that heat waves have become more frequent over most land areas. "

I don't think weather can explain a 60 year trend:

I stated that global warming increases the frequency and duration of heat waves. However, I never said that global warming caused them.

Update 2:

(continued from above)

Nor did I never state that a specific heat wave has caused by global warming.

Update 3:

My added details should have read "Nor did I never state that a specific heat wave was caused by global warming."

10 Answers

  • Trevor
    Lv 7
    10 years ago
    Favorite Answer

    The comment has been made on many occasions that no one event can be taken as proof that the climate is changing. Yourself, your links and the respondents to this question have emphasised this.

    Given that the issue of heatwaves has been raised numerous times in recent weeks I thought I’d do a little research.

    After consulting the International Disaster Database maintained by the Centre for Research on the Epidemiology of Disasters (CRED) this is what I found in respect of extreme temperature events (all figures relate to the period 1900 to 2010).

    In terms of numbers of people killed: 7 of the deadliest heatwaves have occurred in the last 10 years, the exceptions being the 1998 heatwave in India (6th deadliest), the 1980 heatwave in the US (8th deadliest) and the 1936 heatwave in the US (10th deadliest).

    A similar pattern emerges when looking at the number of people affected and the economic impacts. Five of the costliest episodes have occurred since 2000, and with respect to the number of people affected there are six such instances since 2000.

    Statistically, if there had been no change to the climate, we should have seen one instance of each metric occurring since 2000, but on average there has been six.

    Here’s a graph showing how many heatwaves have occurred been each year since 1980:

    Shortly after posting this question you asked a similar question. In my reply I calculated the probability of all the recent heatwaves having occurred naturally as being 1 in 1,267,650,600,000,000,000,000, 000,000,000. In arriving at this figure I assigned an arbitrary probability of 1:1 to each anomalous heatwave as being naturally occurring. But as Dana has shown in his answer, the probabilities are often much smaller than this and so the figure I calculated will be significantly smaller (it probably has closer to a hundred zeros at the end of it).

    Now of course, heatwaves are only one aspect of climate change. But it doesn’t matter which aspect we look at there have already been significant increases in every kind of extreme weather event, with the exception perhaps of the impacts of drought magnitude (the number of droughts has increased but increased mobility, international aid and emergency preparation has helped to lessen the overall impact).

    If we look at storms as an example, there has been a 29% increase in the number of storms that occur globally (38% in the Atlantic) and in the US the number of category 5 hurricanes has dramatically increased.

    In the last 50 years there have been 27 category 5 hurricanes and 551 Atlantic storms, in the preceding 50 years there were 11 category 5 hurricanes and 399 Atlantic storms.

    1910 to 1959 Cat 5 Hurricanes: 10/1924, 4/1928, 4/1932, 2/1935, 4/1938, 4/1947, Dog, Easy, Janet, Carrie and Cleo

    1960 to 2009 Cat 5 Hurricanes: Donna, Ethel, Carla, Hattie, Cleo, Betsy, Beulah, Camille, Edith, Anita, David, Allen, Gilbert, Hugo, Andrew, Georges, Mitch, Floyd, Lenny, Isabel, Ivan, Emily, Katrina, Rita, Wilma, Dean and Felix

    There’s a huge amount of information relating to heatwaves and other climatic and natural disasters on the following websites. Registration is required for full access to the CRED databases, without registering you’re limited to summaries only.


    Prevention Web:

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  • 10 years ago

    Actually there was a very good analysis of the current Russian heat wave yesterday on Open Mind.

    "Clearly, this July [Moscow] has been significantly hotter than previous years in the record. In fact the average daily high temperature for July 2010 is 3.6 standard deviations above the mean of all recorded July values. For a normally distributed random variable, the chance of being so extreme is only 0.0003 — less than 1 chance in 3000. Which agrees with statements from Russian meteorological officials that such a heat wave hasn’t been experienced in Moscow in at least 1,000 years.

    And that means that the suggestion that this heat wave is just a natural variation, not due to global warming, is implausible."

    As you note, Stott et al. (2004) concluded that AGW has made heat waves like the European event of 2003 twice as likely.

    "Using a threshold for mean summer temperature that was exceeded in 2003, but in no other year since the start of the instrumental record in 1851, we estimate it is very likely (confidence level >90%) that human influence has at least doubled the risk of a heatwave exceeding this threshold magnitude."

    But they also note "It is an illposed question whether the 2003 heatwave was caused, in a simple deterministic sense, by a modification of the external influences on climate, for example increasing concentrations of greenhouse gases in the atmosphere, because almost any such weather event might have occurred by chance in an unmodified climate."

    We can't say that any given heat wave or other extreme weather event was caused by or wouldn't have happened without global warming. What we can say is

    1) The frequency of these extreme weather events will continue to increase as the planet continues to warm.

    2) Some of these extreme weather events are exceptionally unlikely to have happened (or more accurately, unlikely to have been as intense) if not for AGW.

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  • 10 years ago

    It is getting more and more difficult to deny that we are, indeed, seeing the effects. If a penny comes down heads four times out of five, that could be chance. If it comes down heads forty times out of fifty, it's a biased coin. Any one event could be chance, but the preponderance of warming-driven events over others constitutes evidence. Weather is merely weather, but enough examples of weather add up to climate.

    Comment: Sarge927 is shameless: "the UK-based climatologists ... admitted the data had to be seriously fudged to "prove" global warming". Total lies. They didn't because it wasn't. Six separate enquiries have now exonerated them of all accusations of dishonesty. Surely he has heard about this?

    poeticmaniac needs to be careful what he's smoking: "global warming is fake the government already national admitted it was a scam to get people to spend money". No relationship to reality.

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  • Jeff M
    Lv 7
    10 years ago

    I think we've already began to see the effects of global warming prior to this including an increase in coral reef bleaching due to desalinization, acidification and warming of the oceans. The advancement of spring and changes in animal habits. Poleward movement of tropical vector-borne diseases.Etc...

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  • 10 years ago

    Probably so, it is just that we do not feel the rise in temperature much because we adapt. It is like putting a frog into cold water and heating it slowly, it dies without noticing the danger.

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  • BGS
    Lv 4
    10 years ago


    The effects of anthropogenic climate change have been observed for decades by those who have been watching. That they are now becoming more obvious to casual observers is interesting though.

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  • 10 years ago

    just polite no point changing anything ww2 did loads of polition maybe the polition protects the ozone layer

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  • 10 years ago

    Nope global warming is fake the government already national admitted it was a scam to get people to spend money, Nope what we are seeng it all natural the earth is constantly maintaining its self there for we have weather. Weather has been keeping this plaint together since it was created.The SIERRA Desert once was a lush tropical place 10,000 years ago and just recently they discovered below it there is more water stored than in the great lakes. 10.000 years ago weather turned a tropical forest into a desert without global worming it can do the same to day if it needs to. Also ever seven years the polar ice caps thaw out the refreezes. Don,t be afraid of nature it knows best people and animals adapt to the climate around them for it constantly changes.The Bible speaks of natural events that will take place like earthquakes for one that will happen as part of the earth maintaining its self.

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  • 10 years ago

    Probably, but I hope not :(

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  • Anonymous
    10 years ago

    Nope. Global warming is a hoax. Google "Climategate" and you'll see the reports about the UK-based climatologists you mentioned and how they deliberately manipulated the data to further their global warming agenda (they admitted the data had to be seriously fudged to "prove" global warming), not to mention their conspiracy to discredit any and all scientists who dared to challenge their opinions or produce scientifically-verified evidence that disproves global warming.

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