Tuesday, September 12, 2006

Climate change - links to hurricanes

Now that even the most stubborn sceptics have accepted that human activity is causing global warming which in turn has potentially catastrophic consequences, they are still not convinced that the recent increase in the intensity of storms and the damages storms and hurricanes cause have any links to human activities.

The theory has been out there for a while. We know how hurricanes work: they are vorteces that spiral around the eye where the air pressure is very low. Warm, humid air from the bottom rises up in a spiral, while cool, drier air from higher up falls down the eye, as it gets sucked in by the low pressure. Hurricanes are born and bred over the sea and they will rapidly weaken as they hit the land, as they quite literally run out of steam, or the warm and humid air. The theory linking global warming to the intensity of the storms is that even a modest rise to seal water temperature would boost these systems, as the air down at sea level would be warmer and more humid.

While the hurricane season, incidence of tropical storms at certain time of a year, is a natural phenomenon that would take place regardless of human activity, the question is whether the amount and intensity of hurricanes have actually risen, and whether this is due to global warming (which now finally is accepted to be largely antropogenic, or originating in human activity). Showing that this link exists would have a major impact on the debate on climate change and what could or should be done about it. To be blunt, it would allow a price tag to be put on how much the American taxpayers are currently paying for the damage their carbon emissions cause. This, in turn, would help to put the costs of lowering those emissions into proportion and make the economic impact of carbon emission cutting more acceptable for politicians, businesses, and citizens.

So far it has been an uphill battle to show that a) climate is changing, b) this would have bad consequences, c) the change is our fault and, d) we can do something about it and finally f) we can afford to do it, in fact, we can't afford not to.

Recent studies, as reported by BBC today, suggest that the link between human activity and storm intensity exists. The researchers at Lawrence Livermore National Laboratory in California concluded that "84 percent chance that external forcing (such as human-caused increases in greenhouse gases, ozone and various aerosol particles) accounts for at least 67 percent of the observed rise in SSTs in the Atlantic and Pacific hurricane formation regions." SST means sea surface temperature, the critical factor in brewing strong storm systems.

So, 84% chance that two thirds of the rise of SST is caused by humans. Doesn't sound convincing enough? Well, to put it the other way around, it is very unlikely if not completely impossible that the rise could have happened without human involvement. And this is the crucial message to take home.

Of course, since climate research is a science, not religion, there is no such thing as "proof" and as the systems involved are mind-bogglingly complex (remember the chaos theory pet example of a butterfly fluttering wings in the Amazon causing hurricanes in the Gulf...) we will never get more than a probability and a theory corroborated by some data. A field day for sceptics, who can complain that the models are missing crucial variables, the results are not bulletproof, historical comparisons of measurements is dodgy due to lack of reliable old data etc.
But, the evidence is cropping up to support the antropogenic theory. And while the cost to deal with the issue is huge, not dealing with it is even more enormous, and is more likely to involve massive loss of human lives, not just inconvenience or loss of property. Just how much more costly it would be not to act, we are beginning to find out.

(Pic: BBC)

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