Aerial photo of the devastation wrought by Super Typhoon Haiyan in the Philippine city of Tacloban. The photo was taken by a crew member on an Armed Forces of the Philippines aircraft flying over the city. For more, see the AFP Central Command Facebook page. | Update 5:30 p.m. MST, 11/12: After I took my friend Keith Kloor to task in the post below, another friend and colleague has taken me to task for not including the most important factor in what drove the specific catastrophe wrought by Haiyan in the Philippines: the social and economic dimensions. See the bottom of this post, where I correct that omission. It's an important point, so please make sure to check it out.| Keith Kloor, a friend and fellow blogger here at Discover, has a provocative post up today titled "The New Normal: Climate Ambulance Chasing." Speaking of catastrophes like Super Typhoon Haiyan, Keith writes:
...you can be sure that trailing behind these disasters, like ambulance chasers, is a brigade of climate-concerned activists, scientists and their enablers in the media. And trailing behind them is an Anthony Watts/Marc Morano led brigade of chortling denialists, whose main objective is to exploit, for ideological/political purposes, the exploitation of disasters by the climate ambulance chasers.
In the post, he takes journalists to task for bringing up the climatic context of storms like Haiyan. Since I've discussed the climatic context of recent extreme weather events here at ImaGeo, I thought it would be a good idea to respond to Keith. So here goes... Dear Keith, Whether you like it or not, the climatic context of Super Typhoon Haiyan IS front and center in the news coming out of the U.N. climate talks in Poland, and both activists and skeptics are making all manner of claims in the aftermath of the typhoon. So I believe science and environmental journalists have a responsibility at least to try to hold up these claims to scrutiny, and to let readers know what can be said with confidence, what's at the cutting edge of science, and what is simply bogus. That is not being an "enabler" of "climate ambulance chasers." It is simply doing our job. With this in mind, here are my abbreviated answers to those questions, starting first with a summary and then delving into the geeky details: It is absolutely true that we should tread very carefully in linking individual storms to climate change. As you point out, this is the province of a field called attribution research. Although this is cutting edge stuff, and thus subject to doubt and uncertainties, scientists have been making progress in their ability to determine the degree to which, if any, climate change may have contributed to an extreme weather event. But that attribution research hasn't been done for Super Typhoon Haiyan. That said, it is perfectly legitimate to point out that while no trend in cyclone activity attributable to climate change has been definitively documented for the globe as a whole, there is evidence for one in the North Atlantic — associated with warming ocean temperatures. Moreover there's reason to believe that sea level rise can exacerbate storm surges to some degree. But in the case of Haiyan, the surge was so high that any contribution from sea level rise was likely to have been small. Lastly, recent research suggests that as the world warms, both the number and intensity of tropical cyclones may increase, although this too is cutting edge research with uncertainties attached to it. I think that is a pretty fair "nut section," if you will, summarizing what can be said about the climatic context of tropical cyclones. And now, here are the geekier details:
Some activists are directly tying Haiyan to climate change. For example, Jamie Henn, communications director for 350.org, wrote in the Huffington Post, "Carbon dioxide is the steroids that leads to grand-slam storms like Haiyan." This is bogus. As you noted in your post, there is a developing field of science focusing on "attribution" — namely, the specific causes of individual storms, including the degree to which climate change may have played a role. But it is a relatively new area of science, and that kind of attribution research has not yet been done with Haiyan. Moreover, climate change is expected to play itself out in changes to patterns of weather over long periods of time. So quick and dirty attribution of individual events to climate change is ill advised in our stories.
We often hear it said that climate change is already well underway, and thus it forms a backdrop to every weather event. Kevin Trenberth, a senior scientist at the National Center for Atmospheric Research, has put it this way: "All weather events are affected by climate change because the environment in which they occur is warmer and moister than it used to be." As science journalists, we cannot simply ignore this point. But it is certainly valid to ask what this really means. In the case of the intense rainfall event we suffered here in Colorado back in September, which led to catastrophic flooding, it meant that the atmosphere may have held as much as 5% more water vapor than it would have without global warming. But that was likely a minor contribution to an event that featured water vapor levels more than 200% above normal.
We know there is no evidence for a systematic increase globally in the Accumulated Cyclone Energy index, or ACE, a measure of tropical cyclone activity, between 1970 and 2012. But there has been a noticeable increase in that measure of cyclone activity in the North Atlantic Ocean since the mid-1990s. A similar measure, called the Power Dissipation Index, or PDI, has followed a similar trend in the North Atlantic. And both trends seem to be associated with changes in sea surface temperature, which has risen more than 1 degree F since about 1970.
What can we say about that association? I'll quote noted hurricane expert, MIT's Kerry Emanuel here. He argues that "there is a strong anthropogenic signal in Atlantic hurricane power." Other scientists disagree. Here is a summary of his argument:
Hurricanes operate off a difference between the temperature of the ocean and the temperature of the atmosphere. And as we add greenhouse gases to atmosphere, that temperature difference increases. And that tends to make hurricanes more powerful. That hurricane power during the period of really good observations, from about 1980 until now, has roughly doubled in the Atlantic. That's a big signal. Now the question is, why has that happened? And the fact that it is so beautifully correlated to sea surface temperature gives us a little bit of a leg up, because it's easier to ask why the sea surface temperature has gone up.
Big caveat: Emanuel points out that only 12 percent of global hurricane activity occurs in the Atlantic. Most cyclones occur in the Pacific and Indian Oceans.
Global sea level has risen, and this contributes to storm surges during big storms. But here, too, it is legitimate for us to ask how much? Brian Walsh of Time Magazine asked that very question in the story you included in your criticisms. Here is what he came up with:
Seas have been rising significantly faster in the Philippine Sea, where Haiyan struck, than the world on average. The higher seas would have worsened flooding, just as sea-level rise amplified the damage from Superstorm Sandy, but given the fact that Haiyan’s storm surges were as much as 20 ft., climate-driven sea-level rise wouldn’t have been the deciding factor in the supertyphoon’s devastation.
That said, let's go a little further. Purely for sake of argument, let's assume that 1,000 people lost their lives from storm surge brought on by Haiyan. (This is a made up number. I'm just using it as an illustration.) Now let's say that sea level rise made Haiyan's storm surge 10 percent worse. That likely would mean that of those 1,000 people who died from storm surge, 100 lost their lives because of an extra push from sea level rise. One hundred lives is a big deal. We can also ask how much extra devastation was caused. Even a 10 percent increase could have equaled something quite significant. My point is not at all that this is what happened with Haiyan. My point is simply that it is the very kind of question we should be asking as journalists — and doing so does not make us enablers of ambulance chasers.
What can we expect going forward? As we both know, we're already committed to a certain degree of global warming because of the carbon dioxide already emitted to the atmosphere, along with a concomitant rise in sea level. So I believe it would be reasonable to say that storm surges are likely to get worse in coming decades because of global warming.
Lastly, what about the strength of storms themselves? Kerry Emanuel has done research showing that as the world continues to warm, we are likely to see an increase globally in both the number and intensity of tropical cyclones. (Go here for a good summary of the study.) But another important caveat: This research is at the cutting edge of computer modeling.
Keith, I agree with you that using a calamity like Super Typhoon Haiyan as just another excuse to trade salvos in the climate change wars is unseemly, at best. I made that very case two days ago in a post here. But when claims are flying around, it is the job of journalists to try to call balls and strikes, and present a clear and accurate picture of what science can say. Even umpires make the wrong call sometimes. So I may have erred in some of what I've said. If I have, I'll correct the record. In the meantime, I remain... Your friend and colleague, Tom |Update: This post was intended simply as a refutation of the claim that journalists who bring up the climate context of extreme weather are somehow enablers of "ambulance chasers." I strongly believe that one of our roles is to call balls and strikes when activists, skeptics and others get attention with their claims. But that's certainly not our only role. We obviously need to put a storm like Haiyan in its full context, and climate is just part of that. With this post, I did not at all mean to imply that the climate science context is preeminent in the Haiyan story. Far from it. What happened is this: A huge and powerful storm bore down on a densely populated coastline, where poverty and shoddy construction abound. And even a weaker storm would have caused a great deal of misery. Seth Borenstein of the Associated Press got the balance just right in his story today. You can find it here. |
