When it comes to Al Gore's high-profile advocacy on the subject of global warming, those seeking to undermine the former Vice-President have seized upon a familiar tactic: They attack his depiction of the science. This even though most climate scientists would probably agree with the view expressed on the leading global warming blog, RealClimate.org, that Gore's depiction of the information has been mostly accurate (albeit perhaps with some "small errors"). Nevertheless, this down-in-the-weeds strategy for assaulting Gore's credibility recently bubbled up to the pages of New York Times, where science reporter William Broad--in an article that RealClimate.org found just as misleading as it found Gore's movie accurate (see also the Times letters section)--sought to inflate those minor errors into a major scandal.
On the basics of climate science--including the fact that humans are driving the recent warming trend--Gore is pretty much unassailable. However, the science gets more complicated as you transition into discussing the specific impacts of global warming, and so one prominent area where critics have tried to undermine Gore involves the ongoing debate over the relationship between hurricanes and global warming. For instance, following Gore's testimony before the House of Representatives on Wednesday, Rep. Joe Barton (R-TX)--who is notorious for his attacks on climate science and climate scientists--unleashed a litany of complaints about An Inconvenient Truth, including the assertion that Gore had claimed there would be "more and stronger hurricanes because of global warming." "The IPCC report does not support this claim," Barton continued (webcast here; see around minute 1:24:00).
In countering this (at around minute 1:34:35), Gore explained:
There is no consensus linking the frequency of hurricanes to global warming, and I've never said there is. It's the intensity of hurricanes. It's also true the scientists say you can't take an individual storm and say, 'this is caused by global warming.' But the odds of stronger storms are going up.
Gore should be careful about using the word "consensus" here--this remains a debated area. Still, his comments are far more consistent with the conclusions of the IPCC report--or to be more specific, the Summary for Policymakers of the U.N. Intergovernmental Panel on Climate Change's Fourth Assessment Report (PDF)--than Barton's are. That document stated (much like Gore) that "There is no clear trend in the annual numbers of tropical cyclones." But it also went on to say:
Based on a range of models, it is likely that future tropical cyclones (typhoons and hurricanes) will become more intense, with larger peak wind speeds and more heavy precipitation associated with ongoing increases of tropical [sea surface temperatures].
Barton, by contrast, was out on a limb in his characterization of the IPCC report. Contrary to his assertion, that report does indeed support the claim that there ought to be stronger hurricanes--if not necessarily more of them--due to global warming. (Of course, an important remaining question is how much stronger the storms will become, and here one still finds differing views among scientists.)
Something similar happened when Gore came before the Senate. This time, the resident global warming contrarian was not Barton but rather James Inhofe of Oklahoma, who has infamously suggested that the whole notion of human-caused global warming itself might be a "hoax." (To watch Inhofe's exceedingly rude cross-examination of Gore, click here and go to around minute 1:11:00). The Oklahoma senator's assertion about hurricanes came in his opening statement, where he said to the former Vice-President:
....you claim a strong new emerging consensus linking global warming to an increase in hurricane intensity and duration...Last year, the World Meteorological Organization clearly rejected this assertion, and other scientists agree.
Inhofe does somewhat better than Barton here, but he too is misrepresenting his source. The World Meteorological Organization summary in question (PDF) is very cautious and depicts a field of science in flux. But it doesn't "clearly reject" the notion that global warming has led to an increase in hurricane intensity and duration. Rather, it states that "there is evidence both for and against the existence of a detectable anthropogenic signal in the tropical cyclone climate record to date," and that therefore "no firm conclusion can be made on this point." However, much like the IPCC, the World Meteorological Organization also said that "It is likely that some increase in tropical cyclone peak wind-speed and rainfall will occur if the climate continues to warm."
In short: While scientists are not all in agreement that hurricanes have changed in a measurable way as a result of global warming, they do expect them to change in the future, and in the direction of greater intensity. Barton and Inhofe have a lot of nerve criticizing Gore if they themselves don't admit this.
Does that mean that Gore's depiction of the science on hurricanes in An Inconvenient Truth is above criticism? No. Everything that Gore says has some basis in science, but perhaps in part because he's cramming in a lot of information, he doesn't always explain all of the nuances and complexities. For instance, in discussing hurricanes, both the book and the film versions of An Inconvenient Truth fail to draw a distinction that Gore himself highlighted in response to Barton, when he noted that "you can't take an individual storm and say, 'this is caused by global warming.'" Members of the public generally do not understand this nuance, and an untrained viewer watching An Inconvenient Truth could easily walk away with the impression that global warming did in some sense "cause" Hurricane Katrina and some of the other storms discussed by Gore, such as 2004's Catarina, the first hurricane on record (and here it's important to note that our records aren't that good) to strike Brazil.
I for one would have preferred to see Gore include this important caveat in his book and film--both for the purpose of completeness and so as to prevent possible misimpressions. Indeed, I was very glad to hear him make the point before Congress on Wednesday. Similarly, I would have preferred to see Gore draw another distinction: While there is indeed an expectation that hurricanes will intensify in the future, scientific debate continues over whether this increase is actually detectable at the present time. (I'm sure Gore knows this, but again, it doesn't come across in An Inconvenient Truth. And he does use the phrase "emerging consensus.")
Nevertheless, when it comes to the science of global warming and its impacts, there's a very significant difference between Gore and his would-be detractors. Gore takes the conclusions of the mainstream scientific community on global warming seriously and for the most part describes them very accurately, albeit with perhaps a few small errors of presentation (which are likely inadvertent) and of omission (some of which may arise from the fact that he has a ton of ground to cover). It's certainly fair to argue that Gore ought to include more nuances and caveats. But for comparison, let's bear in mind that Gore's scientific critics (and especially Inhofe) tend to disregard the large body of accepted science entirely--except when they find something they think they can use to make Gore look bad. And even in these cases, they're usually much more off base, and much more selective, than Gore himself is.
So the next time you hear someone try to criticize Gore about climate science, first check to make sure that their own house is in order.
Most of all, let's not lose sight of the big picture. If you look beyond the scientific details for a moment--something Gore's technical critics don't want us to do--you can quickly see where Gore's message is both the most accurate and the most urgent: We have got to do something on global warming, before it's too late.