Extreme weather is making headlines. Record summer temperatures in Europe and a large number of heat-related deaths in India joined news about severe flooding in Bangladesh, China, and Sri Lanka. And an unusual number of tornados in the United States have been reported.
For its part the UN World Meteorological Organization (WMO) suggests that global warming is linked to these events. It also declared that extremes in weather and climate are setting new records and the number of such extreme events has been rising. (The Bush administration plans to spend $103 million to study global climate change.)
But these reports raise many questions. As the director of the WMO admitted, the results reflect the fact that monitoring and communication of weather conditions arc better than ever before. It turns out that the only certainty is that reporting of extremes is more common, even if the extremes are not.
As it is, little attention is paid to the fact that some of the vulnerability to extreme weather arises from changing human population patterns. Over the years, foreign aid and emergency disaster relief encouraged the building of slums or suburban housing in flood plains. Similarly, air conditioning allows more people to live comfortably in areas subject to hurricanes and cyclones.
In its report, the WMO notes that global averages for land and sea surface temperatures in May arc the second highest since records began in 1880. However, temperatures in the upper atmosphere were not reported. This is no slight oversight. For global warming to be truly global, atmospheric temperatures would also have to be rising. But there is no evidence that air temperatures have risen to match the reports of rising ground temperatures.
Consider the fact that surface temperatures have been increasingly recorded in urban areas or airports that have much more concrete and asphalt than they had even a few decades back. All other things constant, it would be surprising if temperatures taken in such "hot spots" did not increase.
Such alternative explanations tend to be ignored. And so it has become an article of faith that burning fossil fuels increases greenhouse gases (GHG) that lock in heat and cause global warming.
Contrary to conventional wisdom, scientific understanding of climate change remains quite unsettled. In particular, it is not clear that observed global warming trends are significant or relevant to the long-term survival of life on earth. Nor is it clear that attempts to reduce greenhouse gases will offset other factors that influence climate. Indeed, there is a strong correlation between sunspot activity and temperature variations.
In all events, GHGs are not the only possible source of warming trends and not necessarily the most important. Weather and climate patterns depend on influences from oceans and other water systems, the variability of solar radiation, volcanic aerosols, and greenhouse gas emissions, as well as clouds and water vapor, just to name a few.
The UN Intergovernmental Panel on Climate Change (IPCC) considers at least 12 conditions that could change climate. …