Hurricanes and Global Warming
Tuesday, July 24, 2007.
By Larry Smith
In England, a chunk of the country is submerged in flood water and as we enter the 2007 you-know-what season - with 14 named storms and seven hurricanes predicted - a science journalist named Chris Mooney has published Storm World, a book linking hurricanes with the battle over global warming.
Mooney grew up in New Orleans, the city that was smashed by Hurricane Katrina recently, and is the Washington correspondent for Seed Magazine. His new book presents a scientific history of our current understanding of hurricanes and asks if we are making these dangerous storms even bigger monsters than they already are.
His starting point is that since the Earth's atmosphere is warming, and since hurricanes draw their power from the heat energy stored in tropical ocean waters, warmer seas should (all else being equal) produce more intense storms.
This has enormous implications - particularly for us in the Bahamas - because strong hurricanes cause dramatically more destruction than weak ones when they hit land. Although that might sound obvious at first, the fact is that the amount of damage increases at a faster rate than wind speed.
"It has been estimated that a land-falling Category 4 or 5 hurricane, with maximum sustained winds greater than 131 miles per hour, causes 64 times as much destruction as a Category 1 storm (with winds from 74 to 95 mph) and 256 times as much as a mere tropical storm (winds up to and including 73 mph)," Mooney says. "If we're really making the deadliest storms on Earth still deadlier, it will represent one of humanity's all-time greatest foot-shooting episodes. Short of a collapse of the Greenland or West Antarctic ice sheets, it's hard to imagine many hypothesised manifestations of global warming more likely to shock the public or generate a call to action."
Global warming has been high on the scientific agenda since 1988, when the Intergovernmental Panel on Climate Change was set up by the World Meteorological Organization and the United Nations. But only in more recent years has it become a topic of heated dinner table conversation, with former US vice president Al Gore's documentary film, An inconvenient Truth, helping to feed the popular interest.
The IPCC brings together thousands of scientists from all over the world to make periodic assessments of the state of climate science. Their latest report was issued in February, and its conclusions were reached by consensus under the leadership of Dr. Susan Solomon of the US National Oceanic and Atmospheric Administration.
The IPCC does not conduct its own research, it sifts and evaluates the existing peer-reviewed literature to summarise the best available scientific knowledge on climate change. In fact, experts say this process is one of the most ambitious, comprehensive, heavily reviewed, and authoritative knowledge-gathering enterprises ever undertaken.
The February assessment confirmed the "unequivocal" warming of the climate system, as is now evident from increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.
The report also said it was "likely" - meaning a greater probability than 66 per cent - that rising temperatures were a factor influencing the intensity of tropical storms.
As Mooney outlines in his book, more powerful hurricanes are one of the assumed consequences of global warming, "although specific weather events can never be 'caused' by a statistically averaged change in global climate over time, even if they are precisely the kind of events that should grow more common as global warming sets in."
Global warming is caused by a buildup of greenhouse gases (like carbon dioxide) in the atmosphere which help to trap the sun's heat. Most scientists believe that this buildup is the result of human activities such as the burning of vast quantities of fossil fuels during the industrial era: "The warming trend over the past 50 years (0.13 degrees Celsius per decade) is nearly twice that for the last 100 years." the IPCC says.
This warming trend can set off long-term changes in the Earth's climate that threaten both human societies and natural ecosystems. But when scientists began talking about cutting greenhouse gas emissions, they implicated the fortunes of some of the world's most powerful vested interests. And before long, the petroleum and automobile industries had organised to combat the global warming forecasters.
One of their core weapons was to create doubt about the validity of the science itself - the same tactic used by the tobacco industry for decades when scientific research pointed to adverse public health consequences from smoking. And for a while, the climate change skeptics were powerful voices - to the point of influencing George W Bush to reverse his 2000 campaign pledge to cut greenhouse gas emissions.
But the pendulum has swung recently with the collection of new scientific data, to the point that even ExxonMobil acknowledges that greenhouse gases from smokestack and tailpipe emissions are factors in global warming. For years, ExxonMobil had funded think tanks that questioned the science - and whether policies to address global warming would be cost-effective.
For example, the Heartland Institute, an influential libertarian think tank based in Chicago, says that "environmental scares are frequently unsupported by sound science and are often launched to further an anti-corporation, anti-free market agenda. Activists use junk science to stampede the public into fearing chemicals in the air, food, and water, and the possible consequences of poorly understood phenomena such as climate change."
The massive destruction caused by Hurricanes Katrina and Rita in 2005 focused public attention on the relationship of tropical cyclones to global warming. And some well-known climate researchers concluded that warmer seas were indeed fueling stronger storms, although skeptics say this is part of a natural cycle.
According to Kerry Emanuel of the Massachusetts Institute of Technology, "There is some evidence that hurricane intensity is increasing. Records show an upswing of both the maximum wind speed and duration of hurricanes worldwide. The energy released by the average hurricane (again, considering all hurricanes worldwide) seems to have increased by around 70 per cent in the past 30 years or so, corresponding to about a 15 per cent increase in maximum wind speed and a 60 per cent increase in storm lifetime."
A big chunk of Chris Mooney's book details the battles in American scientific and political arenas over whether the unusually active hurricane seasons of 2004 and 2005 were "a portent of global warming's meteorological onset". Indeed, the Bush administration went so far as to censor government scientists, editing their pronouncements on climate change and hurricane intensity to reflect the official "party line".
Mooney reports that, although the Atlantic was less active, globally "2006 - like 2005 and 2004 - featured many incredible hurricanes. That includes what may have been the strongest southern hemisphere storm ever observed, and what is officially the longest-lived intense storm. The records set were yet again consistent with - though still not proof of - a global warming-induced intensification of hurricanes. They didn't make you certain, but they certainly made you wonder."
So the scientific consensus is beginning to shift towards those who see evidence that global warming will produce an upward trend in the destructive power of tropical cyclones. Taking into account rising coastal populations, this could lead to a substantial increase in hurricane-related losses in this century, experts say.
And the consensus is really all we have to go on. We can't pick winners among scientists, Mooney says: "not unless the broader scientific process, in which they all participate (or the bulk of them), brings them together in a conclusion they strongly and collectively accept. On global warming itself, that has happened already. On global warming and hurricanes, it hasn't."
For a world that has endured the Bush Administration's two-term obstruction of any international action to address global warming issues, it is interesting to note that climate change now looms larger than any other environmental threat in the mind of the American public.
A recent poll conducted by the Washington Post, ABC News and Stanford University reported that a third of Americans cite global warming as the world's biggest environmental problem - double the figure from just a year before. And the same poll found that 7 out of 10 Americans want the government to take more action on global warming - including regulating private industry.
With both the Bush Administration and the Kyoto climate treaty rapidly drawing to a close, the focus is on the development of new opportunities for international co-operation on global warming.
Storm World: Hurricanes, Politics and the Battle Over Global Warming by Chris Mooney. Harcourt Publishers, 2007.
Larry Smith writes a column called "Tough Call" every Wednesday for the Bahamas Nassau Tribune. A former reporter and editor, he now operates a communications agency in Nassau (www.bahamasmedia.com). He also blogs at Bahamapundit.
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