Again newspapers and television are packed with stories of environmental degradation, extreme weather and global warming. Consider last year's floods in central Europe and the recent hot weather and forest fires for which global warming is blamed, spurring a widespread demand to limit the emissions of greenhouse gases.
This view comes not only from environmental organisations but also from politicians and researchers. Prominent researcher John Houghton compared extreme weather with weapons of mass destruction and called for political action. But is this analysis accurate?
The UN's Intergovernmental Panel on Climate Change cannot find any significant development in extreme weather in the 20th century, although there is a tendency that global warming is likely to cause more precipitation. This is the conclusion of the IPCC's latest report. Houghton readily cites the World Meteorological Organisation to the effect that global warming has shown itself to give rise to more extreme weather such as heatwaves. Unfortunately, this much-cited news flash from the WMO was only a press release, not based on any research, and when questioned the WMO acknowledged that its results could be explained merely by "improved monitoring and reporting".
Of course, such distinctions fit badly with the general claim that global warming is becoming a WMD.
The intuition would be that as the weather gets warmer, we will get hotter and, consequently, more people will die from heatwaves. But this is a severely flawed argument.
Basically, a global temperature increase does not mean that everything just becomes warmer. Global warming will generally warm minimum temperatures much more than maximum temperatures. In both hemispheres and for all seasons, night temperatures have increased much more than day temperatures. Likewise, most warming has taken place in winter rather than summer. Finally, three-quarters of the warming has taken place the cold areas of Siberia and Canada.
All of these phenomena are, within limits, good for agriculture and people. Yet we are constantly being told that global warming is what brings on heatwaves such as those we're seeing right now. Not correct. Global warming has generally only decreased the number of cold days. The US, northern and central Europe, China, Australia and New Zealand have experienced fewer frost days, whereas only Australia and NZ have had their maximum temperatures increase. For the US, there is no upward trend in maximum temperatures and for China they have been declining.
Of course, as global warming goes on, maximum temperatures will also start to increase. Yet the idea of comparing this with WMDs seems curiously misleading. Yes, eventually heatwaves will cause more people to die from the extreme high temperatures, but what is neglected is that many more people will not die from cold spells. In the US, it is estimated that twice as many people die from cold as from heat, and in the UK it is estimated that about 9000 fewer people would die each winter with global warming. But don't wait up to see the headlines in the next mild winter saying "9000 not dead".
Even if extreme weather is not getting worse, the damaging effects caused by extreme weather are indeed increasing. But the key factor is not global warming. The more important factor for explaining the damaging effects of extreme weather is much more direct in its causality: there are more people in the world, they are wealthier, and many more prefer to live in cities and coastal areas. Accordingly, extreme weather will affect more people than before and, because people are more affluent, more absolute wealth is likely to be lost.
Florida is an example of this development. When Florida was hit by a hurricane in September 1926, the economic loss was $US100 million. In 1992, a similar hurricane destroyed property to the value of $US38 billion. Clearly a bigger disaster -- but not due to a development in extreme weather. The explanation comes from economic growth and urbanisation.
In other words, we are probably getting more vulnerable to extreme weather but this is only weakly related to climate change. It therefore seems tenuous to blame the damage unfolding on global warming and it is meaningless to argue -- as Houghton does -- that the wise political solution is primarily extensive action against global warming.
Although global warming has not had much effect on extreme weather in the past, it might have a greater effect in the future. According to the IPCC, some extreme weather is likely to develop this century. However, we lack reliable data about the consequences for the damage caused by extreme weather in the future.
The only available study is about tropical hurricanes. Here data shows that, although the extent of hurricanes will increase in the future, this effect will contribute to only 5 per cent of the rise in economic damage caused by extreme weather. The other 95 per cent will be due to societal factors such as economic growth and urbanisation.
If our goal is to reduce vulnerability to extreme weather, limiting carbon emissions is certainly not the most cost-effective way. In the Kyoto Protocol, industrialised countries have agreed to cut carbon dioxide emissions by 30 per cent in 2010.
This will be extremely expensive and will have only a negligible effect. The global cost will be large: the estimates from all macro-economic models show a cost of $US150 billion ($224 billion) to $US350 billion every year. At the same time, the effect on extreme weather will be marginal: the climate models show that Kyoto will merely postpone the temperature rise by six years from 2100 to 2106. Most global warming problems will occur in the Third World, yet these countries have many other, more serious, problems with which to contend. For the cost of Kyoto, in 2010, we could permanently solve the biggest problem in the world -- we could permanently provide clean drinking water and sanitation for every person in the world. Should we not deal with the most pressing problems for real people first?
Endorsing Kyoto seems to have become the way to show our willingness to do good. But we can't do all good things simultaneously. I would prefer that we got our priorities straight and dealt with the most important issues first.
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