GWYNNE DYER > Wild weather

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It was 42 degrees centigrade in St. Louis, Missouri, last weekend, about the same as in Saudi Arabia. Along the U.S. Atlantic coast, it was cooler, but not much: 41 degrees in Washington DC, just short of the city’s all-time record. And 46 Americans were already dead from the heat wave.

In Britain, it was incredibly wet. Almost 6 cm (2.3 in) of rain fell on Saturday in parts of southern England, and there were over 20 flood warnings and 100 flood alerts in effect. The wettest April ever was followed by the wettest June (with more than double average rainfall), and July has started the same way.

Russia had its hottest summer ever in 2010, with peat wildfires raging out of control – over 5,000 excess deaths in Moscow in July alone – but this summer it’s wet in Russia too. Last Friday an astonishing 28 cm (11 inches) of rain fell overnight in the Krasnodar region of southern Russia, and flash floods killed 155 people.

It is a big planet, and some local record for hottest, coldest, wettest or driest is being broken somewhere or other almost every day. But these are records being broken over very large areas, in regions where records go back a long time. As Krasnodar governor Alexander Tkachev said: “No one can remember such floods in our history. There has been nothing of the kind for the last 70 years.”
There are very unusual events happening in winter too: last January only 14.7 percent of the U.S. was covered by snow, compared to 61.7 percent at the same time in 2011. At least 300 people died in a cold wave in northern India in the previous January.

One could go on, enumerating comparably extreme weather events in the southern hemisphere in the past couple of years. But that would just be more impressionistic evidence, and no more convincing statistically. The events are too few, and the time period is too short. But it does feel like something is going on, doesn’t it?

The most recent opinion polls indicate that a majority even of Americans now accept that climate change is happening (although, being American, many of them still cling to the belief that it is a purely “natural” event that has nothing to do with human greenhouse gas emissions). But opinion polls are not a good guide in these matters either. Can we really say that something serious is happening, and that it is evidence that the climate is changing now?

No, we can’t. It’s a statistical long-shot, but it is possible that this is just a random collection of extreme events signifying nothing in particular. Occasionally a tossed coin comes up heads six times in a row. But usually it doesn’t.

The best way to approach the question is to ask what we would actually see if global warming had crossed some threshold and triggered big changes in weather patterns. The actual change in the average global temperature would be almost imperceptible: only one or two degrees C (2 to 4 degrees F), or the difference in an average day’s temperature between 9 a.m and 10:30. What we would notice is that the weather is getting wild.

We never really experience the climate; what we feel is the daily weather that it produces. A climate that is changing will produce unfamiliar weather – and if it is getting warmer, it will be more energetic weather. Wilder weather, if you like.

That means hotter, longer heat waves, and bigger storms that bring torrential rain and killer wind speeds. But it can also mean prolonged droughts as rainfall patterns change – and much more severe winters, like the “Snowmageddon” storm that hit Washington, D.C. in February 2010 and shut down the U.S. federal government for a week.

That last phenomenon confuses people who think colder winters prove that the climate isn’t getting warmer, but complex systems like the climate can produce strange local results. As an article by C.H. Greene and B.C. Monger in a recent issue of “Oceanography” points out, the melting of the Arctic sea ice will cause colder winter weather in the temperate regions of the northern hemisphere.

“Since the dramatic decline of Arctic sea ice during summer 2007,” the authors point out, “severe winter weather outbreaks have periodically affected large parts of North America, Europe and East Asia. During the winter of 2011-12, an extended and deadly cold snap descended on central and eastern Europe in mid-January (with temperatures approaching -30 degrees C) ... By mid-February, the death toll had exceeded 550.”

How does melting Arctic sea ice cause colder winters? Much of the solar heat absorbed by the ice-free parts of the Arctic Ocean in the summer is released into the air by evaporation in the autumn. The higher atmospheric pressure in the Arctic weakens the Jet Stream, which allows cold Arctic air masses with a high moisture content to spill out into the middle latitudes. Hence colder winters and more snow in the U.S., Europe and northern Asia.

You can’t prove that all this means we are sliding into a new and steadily worsening climate right now – that the long-threatened future has arrived. The statistics aren’t good enough to support that conclusion yet. But if you have to put your money down now, bet yes.

Gwynne Dyer is a London-based independent journalist.


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Notice on comments

Blue Dotterel

7/19/2012 10:47:37 PM

Mara, Global warming is occurring. That's a fact. To what extent it is natural or caused by human agency has been the real issue. The consensus of the vast majority of qualified climate scientists is that much of it is due to human agency. That is also a fact. Scientitic consensus is rarely wrong, especially on such a well studied issue. Many scientists who do oppose human induced climate change have conflicts of interests, so check your source's background and funding.

mara mcglothin

7/16/2012 5:15:09 PM

BLUE I am perfectly clear on this! The guy at the U of I was a scientist! and had amble scientific data to back up his claims. it didn't happen. The World does go through cycles and temps go up and down, and weather changes, but we have very little to do with it. If we all stopped driving and manufacturing tomorrow what do you think would change?

Blue Dotterel

7/13/2012 9:02:26 PM

Mara, One off announcements in the corporate press, like cold fusion, are not science. Try to distinguish between the two. The corporate press is interested in publishing sensational ideas to sell advertising and make profits. These ideas are often not scientifically tested or confirmed. Climate change is. Al Gore is a politician, not a scientist, but even politicians sometimes realize that truth is more important than propaganda. Neither politico-economic nor religious ideology is science.

The Lion

7/12/2012 6:34:38 PM

mara mcglothin, yes, Al Gore is sneering and rubbing his hands together. Dear Lord, the rapture is not going to happen. Stop ruining this planet for future generations.

mara mcglothin

7/12/2012 4:32:44 PM

Yeah BLUE In 1976 at the University of Illinois, I listened to a man who said that a new ice age was coming and there would be polar bears living on the island of Manhattan within 10 years. It is the "corporate greed" that has produced the propaganda that we have much to do with current or future weather conditions. Al Gore has made millions off an unproven idea, and many scientist have come out against these ideas. . The World goes through phases, and this is simply nothing but the norm.

Blue Dotterel

7/12/2012 9:20:52 AM

The science and climate scientists have been clear about climate change for at least 20 years now. Unfortunately politico- economic ideology and corporate greed have trumped science in the modern world, and paralyzed our ability to react to these global and national security threats. The current extremes may or may not be due to the scientifically predicted consequences of climate change, but it is coming, and political and corporate propaganda cannot change that fact.
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