World of Wonders

When we see things that aren’t, we miss the wonderful things that are.

Extreme Weather Calls for Extreme Care in How We Write about Climate Change

As the death tolls rise in step with temperatures in Russia and flood waters in Pakistan, and with each passing “hottest-on-record” month, it’s tempting to think this summer’s extraordinary weather is incontrovertible proof of global warming.

Russia fighting fires

The sentiment is a common thread of daily conversation; it’s reflected in science blogs and mainstream media. For example, in an article in the Telegraph this week, Environment Correspondent Louise Gray writes that, “Experts…said the recent ‘extreme weather events’ prove global warming is already happening.” (My emphasis.)

But do experts actually say that? And do these events really prove global warming?

The article also includes the following statements: “Climate change experts say global warming could be the cause (of Pakistan floods).” “The world weather crisis…is evidence that global warming predictions are correct.” “(The vice-president of the IPCC) said the ‘dramatic’ weather patterns are consistent with changes in the climate caused by mankind.” (Again, my emphasis.)

The difference between the first and subsequent statements is subtle, but very important. The heatwave, floods and other extreme weather events do not prove global warming is happening. They could be caused by global warming; they are evidence; they are consistent with climate change. But they do not prove it. I suspect that Gray accurately reported the circumspect statements—which are very typical of the cautious and rigorous language used by scientists—but strayed slightly in writing the other; I doubt any climate scientist would make such a definitive statement, and I haven’t come across any quotes employing that specific language.

Why is this difference in language important? Because when we say that heatwaves and floods “prove” climate change, it is no different than deniers making counter-claims that events like a colder than normal winter or an unseasonably cool summer “disprove” it—which many have done.

Toronto

And if we declare that the heat wave and floods are “proof”, what happens if later analysis shows the real cause of these events is unrelated to climate change? It appears that a “blocking event” is affecting the normal flow of the jet stream and stalling weather systems over parts of the globe. These stationary systems in turn result in extreme weather, and at least one researcher has linked blocking events to low solar activity.

It’s easy to imagine the backlash and the damage to climate science credibility if later study shows that certain discrete weather events in 2010 were caused, not by global warming, but by solar activity.

What’s more, when we use this language, we paint a misleading picture of how we know anthropogenic global warming is real. Our certainty is not in individual events like heatwaves or floods. Global warming is just that—it’s global. It is a complex, planet-wide, interdisciplinary phenomenon, one that can only be measured over an extended period of time.

Climate change science—like most scientific ideas—is a jigsaw puzzle comprising many pieces of evidence. Together they form a bigger picture. Each piece adds to the detail and overall conclusion, but no single piece is “proof.” Similarly, a fossil of an archeopteryx is not proof of evolution; it is evidence of the common ancestry of reptiles and birds, and it is what we would expect to find if Darwin was right. Along with countless other pieces of the puzzle put in place over 150 years, it has resolved our acceptance of evolution by natural selection as the foundation for understanding all life. But on its own, the fossil is not “proof.”

This appreciation of how science works is critically important in the wake of the hacked East Anglia e-mails. Deniers view the e-mails as evidence that the climate consensus is wrong; they mistakenly think of climate change science as a house-of-cards rather than a jigsaw puzzle. They think the flaws in personalities, process or transparency revealed by the e-mails are cards which, once removed, bring down the entire edifice. Of course, they aren’t and they don’t; instead, they are puzzle pieces which have to be removed, replaced or repositioned—but that don’t alter the overall picture.

There is no doubt: the headlines from around the world are compelling and startling. This year’s extreme weather strongly supports global warming models. They also provide us with a frightening vision of the future. But only when we view 2010 in the larger context of time and the globe will we see the true scientific meaning of these extraordinary events.

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Filed under: climate change, science literacy, ,

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