Climate Change

Ga. Tech researcher links hurricanes to global warming, attacks climate skeptics

An increasing number of scientists say there is a connection between rising ocean temperatures and stronger hurricanes, with major studies on the subject published recently in journals such as Science and Nature. In today's OnPoint, Judith Curry, a professor at Georgia Tech's School of Earth and Atmospheric Sciences and the co-author of a recent study, explains some of her findings. Curry also addresses criticism of her research and the heavily politicized world of climate science. Plus, she claims that a recent hearing on global warming chaired by Sen. James Inhofe (R-Okla.) excluded key members of the scientific community.


Brian Stempeck: Hello and welcome to OnPoint. I'm Brian Stempeck. Joining us today to talk about climate change and hurricanes is Dr. Judith Curry, a professor at Georgia Tech. Dr. Curry thanks a lot for being here today.

Judith Curry: My pleasure Brian.

Brian Stempeck: Now you're the author of a study that was published in the Journal of Science in September. You were one of the authors talking about how warmer oceans may have been behind some of the stronger hurricanes that we're seeing. Give us a sense of the findings of this report.

Judith Curry: OK. What we did was we look at the period from 1970 to 2004 and we chose this period because this is a period where we have satellite coverage and we can actually look at the global population of hurricanes. What we found was over this period that there was no increase in the number of storms, however the strongest storms, Category 4 and 5 storms, the number of those had almost doubled over this period. And we found this in every ocean basin where they have hurricanes, Pacific, Indian Ocean, as well as the Atlantic. And at the same time this increase of number of Category 4 and 5 storms seems to map with the increase in sea surface temperature over this period. And we put forth a hypothesis that the increase in sea surface temperature was resulting in a global increase in the intensity of the strongest, of hurricanes.

Brian Stempeck: Now a lot of people would say, some of the criticism of this report is saying that you only went back to 1970. So is this enough of a set of data to take a look at this and say this enough for a trend?

Judith Curry: OK, well, you never have all the data you want. As far as the climate data record goes the quality of this data is pretty high. Now if you go back in time during the period 1945 to 1970 we have information about Atlantic and North Pacific hurricanes, but this is only about 15 percent of the global hurricanes. If you go back further in time, say to 1900, we have information about U.S. land falling hurricanes, but that's only 2 percent of the population of global hurricanes. And you can't draw any inferences about what's going on globally from what's going on with U.S. land falling hurricanes. So we simply don't have the information to go back earlier than 1970 to talk about global hurricanes characteristics.

Brian Stempeck: Some people say that this is opportunistic though. We see a major hurricane hit New Orleans and then immediately afterwards we see a lot of environmental groups, Democrats, leaders in Europe come in and say, look, climate change is causing these hurricanes and that's the reason why this is happening. Do you think ...

Judith Curry: OK. There were two papers, Kerry Emanuel's paper which was submitted in spring. Our paper was submitted around the first of July. These were submitted before the 2005 hurricane season. The timing of the publication of these papers obviously coincided with some major hurricanes. We did not plan this in advance, so we had no, it just was a luck of timing that our papers came out right at the time of these very intense hurricanes. So as scientists we're not personally being opportunistic, but certainly the coincidence of these two papers and the two very strong hurricanes that hit the U.S. has certainly focused attention on the subject.

Brian Stempeck: Let's go back to your study a little bit. You mentioned that this is basically a hypothesis saying that the warmer seas could be causing the stronger hurricanes. But at same time I saw interviews with some of the report authors, including yourself, where people say that we're not making a direct correlation here. We're not saying that this is definitely the case.

Judith Curry: Well, OK, they're correlated. The sea surface temperature and the hurricane intensity are definitely correlated. In terms of causality, a correlation does not prove causality. However, we have strong theoretical underpinnings. We have observational, additional observational evidence and also climate modeling simulations that help us understand how this works in terms of increase of sea surface temperatures causing increase in hurricane intensity. There was a beautiful example of how this works and we saw Rita, a little tropical storm before it hit the gulf. Then it went into the gulf. The gulf with several degrees warmer than usual. It intensified and when it went over this very warm loop current it went from a 2 to a 5 in one afternoon. It moved off the very warm loop current and then went down to a 5. You could see how this increase in sea surface temperature was fueling Rita very vividly. I mean sea surface temperature isn't the only factor, but it's certainly is a major factor in determining hurricane intensity.

Brian Stempeck: Do you think there's a scientific consensus on this issue, when you're talking about warmer water leading to stronger hurricanes and climate change being behind that?

Judith Curry: OK. From a statistical point of view, yes, but you can't make the statement about every single storm. Some storms will go over warm water and they won't intensify and this may be for a variety of reasons. It may be because of wind shear, and maybe some dry air moving in at higher levels, that's sort of shutting down the convection. So there's a number of reasons where you can go over warm water and not have a hurricane intensify. So it doesn't hold for every individual storm, but it holds statistically.

Brian Stempeck: But as far as the consensus though that, I mean we hear a lot that climate change might lead to stronger storms in the future. Do you think there is consensus on that issue?

Judith Curry: Probably, but the issue that people, the key part of the debate is whether the increase in sea surface temperature, that we see, is caused by greenhouse warming or whether it's natural variability. That's where most of the debate is centered around, although people who don't like that conclusion are looking to find other aspects of our argument to pick on, but it's really not holding up. The key issue debate is really whether or not this increase in sea surface temperature is associated with the burning of fossil fuels.

Brian Stempeck: Now one of the major critics of these kinds of studies is William Gray who's a professor at Colorado State and one of the, I guess you could say one of the first major hurricane forecasters. What he says, one of the criticisms that he brought up about the MIT study and your own, was saying that at the same time that in the Atlantic Ocean you have these hurricanes increasing in strength and a greater number of them. He said you don't see that in the other hurricane basins. I know you just said the opposite of that.

Judith Curry: OK. You do, Bill Gray, to my knowledge, has never published any research on global hurricane statistics, OK? He hasn't looked carefully at the hurricanes in other basins. If he has he hasn't published this. So he's making a statement that is not supported in the scientific literature. So I don't really have an answer for that. The data that we use is publicly available data. You can pull it off the Web site, OK? If he has some secret data set that I don't know about, it's just not out there in the published literature for scientists to look at. So it's not a real useful statement.

Brian Stempeck: Now at the same time though even these other people have criticized this as well, you have Max Mayfield, who's the head of the National Hurricane Center and who recently testified before Congress. And he said that warmer water is probably only caused hurricanes to get about 5 percent stronger. He is, again, disagreeing with your study.

Judith Curry: OK. He's basing that on climate model projections, simulations. Now climate, these are the same people who say there is no greenhouse warming, but then they're believing one particular prediction of a climate model. The climate models do a good job at predicting sea surface temperature. They don't do a great job at predicting precipitation or hurricane intensity. So that conclusion is less robust. I mean look at even the weather forecast of hurricanes. They can do a good job on the track. They do not do the job on intensity. There are some very complex things going on in intensity that we don't do very well with the models. So using a climate model projection to disprove our data set doesn't quite make sense. We should be using our data to test the models, not the models to discredit our data.

Brian Stempeck: Clearly this is a very touchy subject when you're talking about politicians dealing with climate science. And this is an issue we've been hearing about as White House officials resign or the White House comes under fire for certain things it did to an EPA report on climate change. We've also talked a little bit about Senator [James] Inhofe holding hearings on climate change. Do you think that science and politics is getting too muddled and what's the solution to that?

Judith Curry: It is extremely muddled. In a rational society you look at the scientific evidence. There's a lot of political motivation going on and discrediting research related to greenhouse warming. And I'm having a hard time trying to understand where that's coming from because a lot of the energy companies seem to get it, the financial sector seems to get it. It's not a simple, a lot of Christians seem to understand this problem.

Brian Stempeck: There's a wide diversity of people.

Judith Curry: There's a wide diversity of people, so I don't understand why a certain group of politicians and the media are so vehement against us. I don't understand.

Brian Stempeck: Well, what does it say to you that we saw Senator Inhofe have a hearing in the Environment and Public Works Committee last week and Michael Crichton, the author of a global warming was invited to testify?

Judith Curry: OK, they invited two people to testify. Michael Crichton, the author, and Bill Gray, who's an anti-greenhouse warming person. The American Association for the Advancement of Science, who publishes the Journal of Science, tried to get Peter Webster to ...

Brian Stempeck: He's the co-author of this report.

Judith Curry: ... give testimony. He was the lead author of the report. They tried to get him to be invited. They would not invite him, instead the AAAS was able to setup a briefing that Peter Webster did, off the record so to speak, to the congressional aides of the people on the committee, but they would not allow him to make testimony for the Congressional Record.

Brian Stempeck: Do you think that's an isolated incident? I mean is it just Senator Inhofe or do you think it's the rest of Congress who's missing this message?

Judith Curry: Not the rest of Congress, about half of Congress. Again, it's become very politicized and when you're in an environment where people choose not to believe in evolution because it goes against their religious beliefs that opens the door to choosing not to believe other scientific evidence because it's inconvenient. I mean it's anti-capitalist or it's inconvenient or whatever. We're starting to see a lack of rationality, where people are discounting science.

Brian Stempeck: Do you think politicians are missing a real wake-up call here? I mean you have the study from Dr. Emanuel, you have the study from yourself.

Judith Curry: They're missing a real wake up call. With the hurricane problem, I mean we have to do some serious adaptation to face this problem in terms of the engineering and disaster management and stuff that we need to do for our coastal regions. In terms of the burning of fossil fuel issue, I mean it's already too late for us to do anything that's going to help the hurricane problem in the short term. Not that we shouldn't do something about greenhouse gas emissions for longer term issues, but it's already too late to save us from problems that we're facing over the next few decades.

Brian Stempeck: Because the carbon dioxide is really ...

Judith Curry: It's high and it's not going to go low. There's nothing that's going to bring those temperatures back down to the levels they were in the 1970s over the next few decades.

Brian Stempeck: One last question for you. The American public also doesn't seem to be totally getting the message here. There was a survey done by the Washington Post and they found that about 56 percent of the people think global warming is happening. That was about the same as six months ago, even after the hurricane. Do you think that message is also getting lost with American citizens?

Judith Curry: It is. We're making progress. Ten years ago we were having the debate as to whether the earth was warming or not. Most people think that the earth is now warming, but they attribute it to natural causes rather than to burning of fossil fuel. So the terminology global warming is getting convoluted in terms of whether it means the temperatures are increasing or whether it means that burning of fossil fuels is actually the cause. So people interpret global warming in different ways.

Brian Stempeck: Do you think the American public though understands how much of a problem this is?

Judith Curry: The most visible issues have been the warming in the Arctic and also like the melting of the Peruvian glaciers and while there are certainly socioeconomic impacts associated with this and very visible, you can see the glaciers shrinking, it hasn't been a crisis. But if global warming, greenhouse warming, is causing an increase in intensity of hurricanes, like Katrina, then we have a catastrophe and crisis on our hands. And it's this sort of crisis potential that has gotten people's attention in a way that the melting of the ice caps in the Arctic and the Peruvian glaciers hasn't really captured the public's attention. I mean everybody felt the effects of Katrina. Again, when we went to the gas pumps and had to pay a very high prices for gas right after Katrina and seeing refugees from Katrina in our own communities. So everybody in the U.S. is feeling that in a way that we haven't, weren't impacted by stories about the Arctic and the Peruvian glaciers.

Brian Stempeck: All right. Dr. Curry we're out of time. We're going to stop there. I'd like to thank our guest today that was Dr. Judith Curry of Georgia Tech. I'm Brian Stempeck. This is OnPoint. Thanks for watching.

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