For some years now, the debate over global warming has been dominated by fear. Understandably frustrated that their message might not be getting through, climate activists have been ratcheting up the rhetoric to the point where one could be excused for wondering whether they are quoting from scientific journals or the Book of Revelations. If nothing is done, we've been told, global warming would soon destroy "up to 40 per cent of the Amazonian forests," cut African crop yields in half by 2020, turn the American Southwest into a new dust bowl within a few decades and melt the Himalayan glaciers, causing them to disappear completely "by the year 2035 and perhaps sooner."
All very frightening, but none of it was based on solid science.
The chief Cassandra in this chorus of doom has been Al Gore, whose 2006 Oscar-winning documentary An Inconvenient Truth was unabashedly (and rather accurately) marketed as "the most terrifying film you will ever see." Mr. Gore rightly was awarded the 2007 Nobel Peace Prize for putting climate change on the global agenda, but his penchant for hyperbole - as in "we have just 10 years to avert a major catastrophe" or we must take "large-scale, preventative measures to protect human civilization as we know it" - isn't likely to win him any prizes for accuracy or good science.
Here's a case in point. Mr. Gore and his acolytes speak darkly of the likelihood that, because of global warming, sea levels that may rise 15 or 20 feet over the next century. Let's put aside for the moment the fact that, according to the best research we have (from the UN's climate panel, which shared the Nobel Prize with Mr. Gore), global sea levels are not likely to rise more than about 20 inches by 2100 - a level that history shows we can deal with quite easily. Rather, let's imagine that, over the next 80 or 90 years, a giant port city - say, Tokyo -found itself engulfed by a sea-level rise of the magnitude Mr. Gore suggests. It's a truly awful prospect, isn't it? Millions of inhabitants would be imperilled, along with trillions of dollars worth of infrastructure. Without a vast global effort, how could we possibly cope with such a terrifying catastrophe?
Well, we already have. In fact, we're doing it right now. Since 1930, excessive groundwater withdrawal has caused Tokyo to subside by as much as 15 feet. Similar subsidence has occurred over the past century in a vast range of cities, including Tianjin, Shanghai, Osaka, Bangkok and Jakarta. And in each case, the city has managed to protect itself from such large relative sea-level rises without much difficulty.
The point isn't that we can or should ignore global warming. The point is that we should be wary of fear-mongering. More often than not, what sounds like horrific changes in climate and geography actually turns out to be quite manageable. In research funded by the European Union, climate scientists Robert J. Nicholls, Richard S.J. Tol and Athanasios T. Vafeidis recently studied what would happen in the unlikely event that the entire West Antarctic Ice Sheet collapsed. The result, they found, would be a sea-level rise of 20 feet over the next hundred years - exactly Mr. Gore's nightmare. But how calamitous would this really be?
Not very. According to these scientists, a 20-foot rise in sea levels would inundate about 16,000 square miles of coastline and affect more than 400 million people. That's a lot of people, to be sure, but it's hardly all of mankind. In fact, it amounts to less than 6 per cent of the world's population -which is to say that 94 per cent of the population would be unaffected. And most of those who do live in the flood areas wouldn't even get their feet wet. That's because the vast majority of those 400 million people reside within cities and other areas that could - and would - be protected relatively easily. (Remember Tokyo?) As a result, only about 15 million people would have to be relocated. And that's over the course of a century.
The fact is, trying to scare the socks off people with end-of-the-world rhetoric doesn't make the world a better or safer place. Yes, a startling statistic combined with some hyperbolic prose will make us sit up and pay attention. But we quickly become desensitized, requiring ever more outrageous scenarios to move us. And as the scare stories grow more exaggerated, so, too, does the likelihood that they will be exposed for the exaggerations they are - and the public will end up tuning the whole thing out.
This may explain recent polling data showing that public concern about global warming has declined precipitously in recent years. For instance, a Gallup Poll found that the number of Americans who regard global warming as a serious problem has declined from 40 per cent in 2008 to just 32 per cent this year; the same poll also showed that the number of those who believe the seriousness of the problem has been greatly exaggerated has shot up from 30 per cent to 48 per cent over the past four years. Similarly, an Ipsos MORI poll published in the U.K. last June found that just 28 per cent of Britons are "very concerned" about climate change, down from 44 per cent five years ago. And in Germany, Der Spiegel magazine reported survey results showing that only 42 per cent feared global warming, compared with 62 per cent in 2006.
As these numbers imply, fear may be a great motivator, but it's a terrible basis for making smart decisions about a complicated problem that demands our full intelligence.
Bjørn Lomborg is the author of The Skeptical Environmentalist and the subject of the documentary Cool It , being launched at the Toronto International Film Festival.