Thu, Jul 31, 2003 - Page 9 News List

Effects of global warming and how to fight it still open to debate

There are many factors that could contribute to so-called global warming, but much of the evidence is shaky and can be interpreted in more than one way

By Christopher Lingle

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 US have been reported.

For its part, the UN World Meteorological Organization (WMO) suggests that global warming is linked to these events that have led to escalating death tolls and more wreckage. It also declared that extremes in weather and climate events are setting new records and the occurrence of such extremes has been rising in numbers.

But these reports raise as many questions as they are raising eyebrows. As the director of the WMO admitted, these results simply reflect that monitoring and communications of weather conditions is 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 human-population patterns and how the vulnerability to extreme weather arises from how they change. 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 points to global averages for land and sea-surface temperatures in May being 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 rising. But there is no evidence that air temperatures have risen to match the reports of rising ground temperatures.

Consider 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 remaining the same, 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 upon influences from oceans and other water systems, the variability of solar radiation, volcanic aerosols, 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. Of these, only greenhouse gases have come under the close scrutiny of the scientific community. Uncertainty over the influence of the other conditions means that they could worsen the warming trend or reduce it or cancel it out completely.

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