Hurricane Expert Reassesses Link to Warming
By
Andrew C. Revkin
New Orleans after Katrina struck. (Associated Press)
A fresh study by a leading hurricane researcher has raised new questions about how hurricane strength and frequency might, or might not, be influenced by global warming. Eric Berger of the Houston Chronicle
nicely summarized the research on Friday.
Kerry Emanuel of M.I.T. (Jodi Hilton for The New York Times)
The research is important because the lead author is Kerry Emanuel, the M.I.T. climate scientist who in the 1980’s foresaw a rise in hurricane intensity in a human-warmed world and in 2005, just a few weeks before Hurricane Katrina swamped New Orleans, asserted in a Nature paper that he had found statistical evidence linking rising hurricane energy and warming.
That work was supported by some subsequent studies, but refuted by others. Despite
the uncertainty in the science, hurricanes quickly became a potent icon in environmental campaigns, as well as in “
An Inconvenient Truth,” the popular climate documentary featuring former Vice President Al Gore. The message was that global warming was no longer a looming issue and was exacting a deadly toll now.
The new study, in the Bulletin of the American Meteorological Society, is hardly definitive in its own right, essentially raising more questions than it resolves. But it definitely rolls back Dr. Emanuel’s sense of confidence about a recent role for global warming. (The
abstract is here. A pdf is
downloadable on Dr. Emanuel’s ftp page.)
I queried Dr. Emanuel about it and he sent this note Friday night:
The models are telling us something quite different from what nature seems to be telling us. There are various interpretations possible, e.g. a) The big increase in hurricane power over the past 30 years or so may not have much to do with global warming, or b) The models are simply not faithfully reproducing what nature is doing. Hard to know which to believe yet.
The study essentially meshed two kinds of computer models — the massive global climate simulations used to project long-term consequences of building greenhouse gases and small high-resolution simulations of little atmospheric disturbances that can grow into hurricanes. When hundreds of potential storms were seeded across warming oceans, some places in some computer runs — like the North Pacific — saw more activity, but others saw less intensification and fewer storms.
As Dr. Emanuel told Eric in the Chronicle:
“The take-home message is that we’ve got a lot of work to do,” Emanuel said. “There’s still a lot of uncertainty in this problem. The bulk of the evidence is that hurricane power will go up, but in some places it will go down.”
The fresh findings, and Dr. Emanuel’s willingness to follow the science, remind me of something he told my colleague Claudia Dreifus in 2006: “[i]t’s a really bad thing for a scientist to have an immovable, intractable position.”
On his SciGuy blog, Eric discusses some of the
ramifications of Dr. Emanuel’s new storm study:
• This should put to rest a lot of the nonsense about a global warming conspiracy among scientists. Emanuel, faced with new evidence, has moderated his viewpoint. That’s what responsible scientists do, and most are responsible. The amount of scientist-bashing when it comes to global warming is generally quite deplorable.
• Anyone who doubts that the threat of large hurricanes is still being used as part of global warming campaigns should look no further than the energy and climate platform of a presidential candidate [pdf alert], who writes, “Global warming is real, is happening now and is the result of human activities. The number of Category 4 and 5 hurricanes has almost doubled in the last 30 years.”
• If you’re a skeptic, and you welcome these results, please remember that these are the same climate models you bash when they show global temperatures steadily rising during the next century.
They are solid points that hold lessons for advocates on both sides of the charged debate over climate science and its implications for society. There are lessons here
for journalists, too. Science is a trajectory toward understanding, not a set of truths. Sometimes that can be inconvenient, whether writing a headline or advocating for a climate bill.
But somehow society has to learn how to be comfortable with this aspect of the scientific enterprise, while not fuzzing out because things aren’t crystal clear. As Stephen Schneider, a veteran climatologist at Stanford, recently mused, the question is, “Can democracy survive complexity?”
It’s clear that Dr. Emanuel’s admonition about the need for a lot more work applies beyond the realm of science, as well.
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