Katrina as Warm-Up Act?
Last week a friend of mine e-mailed to note that this hurricane came quickly on the heels of last summer's series of big storms in Florida, as well as the tsunami in the south Pacific that struck over the winter. We agreed it didn't seem like a coincidence; and as I noted in a previous post, to me one of the lessons of Katrina is that we can no longer view homeland security, fuel dependence and global warming as separate phenomena: they're inter-related, and so must be an approach to address and mitigate their effects.

This article from Fortune suggests that we'd do well to find some answers sooner rather than later, as storms of this magnitude are becoming increasingly common:

[L]ess than a month before Katrina hit the Gulf Coast, Massachusetts Institute of Technology researcher Kerry Emanuel published a portentous paper in the journal Nature that illustrated how hurricanes' destructive potential has risen dramatically over the past few decades, in tandem with global warming. And a few weeks before Emanuel's paper, the Association of British Insurers issued an equally ominous report on the growing financial risks posed by extreme weather events due to global warming. It predicted that the U.S. may suffer insured losses from single hurricanes of up to $150 billion in 2004 dollars. (To put that in perspective, Hurricane Andrew racked up insured losses of about $20 billion, in 2004 dollars, when it slammed Florida and Louisiana in 1992.)

While the great majority of climate researchers believe that global warming is real (and also that it is partly caused by human emissions of greenhouse gases such as carbon dioxide from burning fossil fuels), no one says Katrina sprang directly from the warming—that would be like arguing that a particular stock's plunge last Tuesday was caused by the onset of a bear market a year ago. But Emanuel and other experts have warned for over a decade that global warming may be creating an environment prone to more violent storms, droughts and other weather extremes, just as a bear market can pave the way for an outsized drop in a particular company's stock price.

Global warming is certainly controversial—while some researchers see evidence that it's contributing to the recent uptick in extreme storms, others argue that the number of bad hurricanes in recent years merely reflects a natural weather variation. But the science of how warmer weather induces violent storms isn't. Hurricanes suck energy from warm waters to drive their winds. So as sea-surface temperatures rise, the storms absorb more energy that gets pumped out in the form of high-speed winds.

To be sure, most of the escalating property losses from hurricanes in recent years stem from the fact that more and more people are putting their homes in harm's way. From 1980 to 2003, the U.S. coastal population grew by 33 million, and is expected to swell by a further 12 million by 2015, according to the British insurers' report.
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The British insurance association report, titled "Financial Risks of Climate Change," was similarly cautious: Rising losses from extreme weather are mainly due to the rising number and value of property in harm's way, it states, though the "trends to date (in devastating weather) are consistent with what we might expect as climate change intensifies." But the report's survey of recent weather extremes is anything but reassuring. Among other things, the study found that:

* Each year since 1990, there have been at least 20 weather events categorized as significant natural catastrophes. There were only three years that bad among the 20 years preceding 1990.
* Four hurricanes that hit the U.S. last year racked up a record $56 billion in total losses over a period of just a few weeks, setting an annual record for such losses.
* Last year 10 typhoons hit Japan, four more than the previous record, making it the costliest year ever for typhoon damage there.
* In 2003, Europe suffered the hottest summer of the past 500 years, causing 22,000 premature heat-related deaths. Accompanying wildfires caused $15 billion of losses. Changes in the weather appear to have already doubled the chance of such hot summers.
* The number of severe winter storms in Britain has doubled over the last 50 years.

The report also notes disturbing recent data indicating that Atlantic hurricane activity is on the rise. The data aren't clear cut—hurricane activity goes up and down in decades-long cycles related to changes in ocean currents, potentially masking a long-term rise due to global warming. Still, the average number of hurricanes in the current "up" cycle, which began in the mid-1990s, is higher than during the previous upswing—a indication that global warming is boosting the effects of the longstanding, natural variation in hurricane activity.

There's no political screed buried in here: yes, the Bush administration has totally ignored global warming, but the Democrats haven't been all that much better, and Bill Clinton always seemed to have more energy for voter-friendly "micro-initiatives"--a school dress code here, a V-chip there--than for pushing the sacrifice and change that a robust policy response would have required. The lesson, I guess, again points to our national disinclination toward planning ahead. The likely costs of this tendency are, to say the least, pretty daunting.