Monday, December 28, 2009

Global warming: Beliefs versus science

Dr. John Christy, director of the Earth System Science center and professor of atmospheric science at The University of Alabama believes the Jury is still out on the matter.

Iam in something of a unique position in the contentious, highly-politicised debate about global warming.

Although I publish data showing a long-term global warming trend, I have been labelled a global warming skeptic, in part because my research does not confirm the cataclysmic climate predictions produced by climate models.

Every month for 20 years, my colleague Roy Spencer and I have published global temperature data collected by the US weather satellites. This is the most comprehensive temperature data available, covering over 95 percent of the globe.

For about a decade, these data have shown no warming. Since late 1978, the data show a long-term warming trend of about 0.13 C per decade, but which is slower than models project. My skepticism about (among other things) the reliability of climate models has no bearing on the climate data and the peer-reviewed climate research that we publish.

Unfortunately, much (if not most) of the climate debate over the past two decades has been driven not by what we know about the climate system, but by what some people believe to be true. As a former Baptist minister, I understand the power of belief and faith. I understand the role of faith in a person's spiritual life.

As a scientist, however, I also understand that when it comes to the climate we must appeal to science — not depth of feeling or arguments from authority — if we want to know what is really happening to the climate and what our proper actions should be.

My research and that of others, suggests that we do not know as much about the climate as the public has been led to believe. There are claims, for instance, that all types of weather-related problems (droughts and floods, violent storms and so forth) are becoming more frequent and violent. Fortunately, scientists keep records of such things and a calm, systematic study of the climate history shows that while there are natural cycles there is no long-term increase in these events. The scientific numbers, for instance, show a slight decline in the number of tornadoes in the US since 1950.

In fairness, it should be noted that one significant problem in this debate is that scientists don't really know as much about the climate as we should. There are numerous gaps in our knowledge that cause some of us to advocate caution and "going slow” when actions mean reducing economic progress in places were it is desperately needed.

Given the inherent complexity of the task, there are fundamental limits to what climate models can do. There are so many chaotic, complex and poorly understood processes in the climate system that long-term climate predictions should always be suspect. Obviously, we need more observational research. (Easy for a scientist to say.) We need better systems for collecting data, so, we can do a better job of understanding the intricate interplay of the climate's many pieces, including how clouds and heating processes interact. This is a fundamental requirement for improving climate models. Understanding what the climate does will lead to a better understanding of why it does and what it does. Until that happens, we should all be cautious not to confuse what we believe with the little that we actually know about the climate.

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Source :
IIPM Editorial, 2009


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