Today marks the official start of North Atlantic hurricane season. So…

One of the key differences between genuine climatology and anti-scientific denialism of anthropogenic climate change is the flexibility of the former and the stubbornness of the latter when it comes to our ever-evolving understanding of how the world works. The connection between hurricanes and climate is a perfect example.

When the “An Inconvenient Truth” crew was filming Al Gore deliver his now-familiar presentation, they couldn’t have anticipated that two major hurricanes would, as if on cue, roar through the Gulf of Mexico and inflict some $80 billion in damages to the U.S. coast. From a marketing point of view, the timing was perfect. When the film was released the next year, a mirror image of Katrina’s cloud pattern Photoshopped into the emissions of a smokestack told the whole story as a publicity poster. Later, Gore added a long series of satellite photos of the recent hurricane activity to his presentation, the one he trained a couple of thousand activists to take to the world.

The scientific basis for linking hurricane activity and global warming was relatively weak in 2005, although at the time, the papers that scientists like Kerry Emanuel were publishing suggested that a warming ocean should increase tropical cyclone intensity, if not frequency. Emanuel’s 2005 Nature paper that received the most attention concluded that “future warming may lead to an upward trend in tropical cyclone destructive potential.”

In the two or three years that followed, however, a lot of second guessing was done, and more than a few scientists voiced their doubts about the strength of the link. The objection was not so much that global warming won’t make storms more frequent or powerful, but that we don’t really understand enough about how hurricanes form and evolve, or just what the historical record is, to able to state with sufficient confidence just what will happen as the Earth warms. Chris Landsea, a climatologist who is sometimes falsely included in the tiny list of scientists who reject AGW, wrote in Eos in 2007 a typical summary of the problem:

Researchers cannot assume that the Atlantic tropical cyclone database presents a complete depiction of frequency of events before the advent of satellite imagery in the mid-1960s…

Climate denial bloggers regularly pummeled scientists with accusations that they had overstated the link, turning hurricanes into something of an albatross rather than an icon of global warming.

But of course, those accusations did nothing to affect the actual science, which continued apace. To someone who only occasionally checks in with the climate journals, it might seem like the pendulum was forever swinging back and forth between alarmism and dismissal. But to those working inside the field, it was a different story. the period of the pendulum continues to shorten, and this year we’ve seen several papers that suggest we might finally be getting a decent idea of what’s really going on.

In Februrary, Nature Geoscience published the latest thinking from a World Meterological Organization Panel, which included Emanuel, Landsea and several other leading researchers. Here’s their conclusion:

… future projections based on theory and high-resolution dynamical models consistently indicate that greenhouse warming will cause the globally averaged intensity of tropical cyclones to shift towards stronger storms, with intensity increases of 2-11% by 2100. Existing modelling studies also consistently project decreases in the globally averaged frequency of tropical cyclones, by 6-34%. Balanced against this, higher resolution modelling studies typically project substantial increases in the frequency of the most intense cyclones, and increases of the order of 20% in the precipitation rate within 100 km of the storm centre.

Just a few weeks ago, Emanuel took another stab at the notion that some climate models were predicting fewer hurricanes, not more. in a paper delivered to the 29th Conference on Hurricanes and Tropical Meteorology in May, he wrote that those models don’t adequately capture the complexities of the interaction between air near the surface of the ocean and stratosphere.

“My results suggest that future warming may lead to an upward trend in tropical cyclone destructive potential, and–taking into account an increasing coastal population — a substantial increase in hurricane-related losses in the twenty- first century.
lead to an upward trend in tropical cyclone destructive potential.”

Does all of this mean Al Gore was right to focus so much on hurricanes? At the time, it can be argued he was getting ahead of the science and maybe that’s true. But the point is, science is willing to admit that conventional wisdom is not perfect. Given the dearth of hard data five years ago, the best anyone could do was made a rough guess, which is what both Gore and the climatology community were doing. Given the stake if that guess turns out to be right, is that really such a bad thing? At worst, you can accuse Gore and perhaps some scientists of not communicating the involved degree of uncertainty well enough.

Compare that with the refusal of many deniers to accept their errors. For example, no matter how many times you point out that water vapor is not a climate forcing, but a feedback, the argument never seems to go away. Same with the notion that the world stopped warming in 1998. The data say otherwise, but it’s hard to convince those who haven’t bothered to study the facts first. Are there really 30,000 climatologists who object to the IPCC consensus? No. But that meme is proving extremely hard to kill.

So, as we begin the 2010 hurricane season, which could be relatively active, it would wise not to jump on every storm as proof of anthropogenic global warming. But it would be an even bigger mistake not to think about the consequences of more powerful, and perhaps more frequent, hurricanes in the decades ahead. Are we really comfortable with even a small risk of leaving such a legacy for our offspring?


  1. #1 Lance
    June 2, 2010


    It is a bit precious to act like alarmists were circumspect and cautious about their claims of an AGW-hurricane link when in reality the claim was trumpeted rather breathlessly by not only Al Gore but many other AGW supporters.

    Then after downplaying all of this scaremongering you try to sound rational and reasonable by, correctly, pointing out the fact that no causal link can be demonstrated by empirical evidence.

    Of course not content to leave it there you reference a statement from a review panel that just says that computer models disagree with each other about whether there “might” be “some” effect on hurricanes “if” the climate were to warm.

    You then conclude by undoing all of this by making a completely illogical and emotional appeal to saving future generations of children from what you just stated was an unverifiable increase in hurricanes from AGW.

    Also Chris Landsea resigned from the IPCC stating in a lengthy resignation letter,

    I personally cannot in good faith continue to contribute to a process that I view as both being motivated by pre-conceived agendas and being scientifically unsound.

    So I think it’s fair to say that he doesn’t share your opinions on the subject of a hurricane link or AGW in general.

  2. #2 James Hrynyshyn
    June 2, 2010

    Lance: Funny you should bring this up. I interviewed Landsea a couple of years ago on this very subject. Here’s part of what he said:

    “I think global warming is real and man-made, at least a lot of it is, and there’s a lot of things to be concerned about…. I do agree there should be an increase in intensity because of global warming.”

    He just said the available data don’t support the kind of increase the models suggest.

  3. #3 Erasmussimo
    June 2, 2010

    Lance, you write:

    in reality the claim was trumpeted rather breathlessly by not only Al Gore but many other AGW supporters.

    You are attempting to characterize the position of “AGW supporters” — an attempt that cannot possibly have any rigor. Sure, we can both recall instances of such behavior. But how many instances? And how much certainty did they claim? And were those declarations made by scientists or bloggers? Mr. Hrynyshyn has already explained that scientists as a group were rather conservative in their reactions to Mr. Gore’s representations. So are you really going to base your statement upon a random collection of quotes from the Internet? Do you believe that I would not be able to come up with a large collection of astoundingly stupid claims made every day by denialists? You’re complaining about some statements by some bloggers some years ago, but the debunking of idiotic denialist claims is an ongoing process, and the gushing of denialist idiocy on the Internet outdoes the output of the blown-out BP well in the Gulf of Mexico.

    Ultimately, however, the argument that “once upon a time, somebody somewhere said something stupid in support of AGW” is irrelevant. What *is* relevant is Mr. Hrynyshyn’s point that scientists respond to changes in data, while denialists NEVER learn.

  4. #4 Lance
    June 3, 2010


    A Google search of “Global warming” and “Hurricanes” returns 1,960,000 hits. The vast majority of them are scare stories or exaggerations based only on the sparse number of studies that support such a link while ignoring the many more that do not.

    This scare tactic has been part and parcel of the AGW campaign for many years and was despicably exploited after hurricane Katrina.

    One of our host’s heroes, James Hansen, has recently used this meme to hawk his doom’s day screed, Storms of My Grandchildren.

    Pretending that the majority of AGW proponents have been coolheaded and dispassionate on the issue is egregiously disingenuous.

  5. #5 Classless M
    June 3, 2010

    Another Hyrnytyntyn fail blog.

  6. #6 Michael Heath
    June 3, 2010

    Given Lance is a fierce denialist almost perfectly ignorant of the actual science, I highly doubt he’s even read and comprehended Dr. Hansen’s book prior to describing it as a “screed”. He’s certainly made arguments contra the empirical peer-accepted facts reported in Dr. Hansen’s book which I speculate is why he attempts to discredit it. In fact here’s one mere example of Lance’s many astonishingly ignorant arguments regarding the science:

    Here is the only relevant observed fact. The average global temperature has risen less than one degree Celsius in the last century and not at all in over ten years. This does not a catastrophe make.

    I have made it clear to my senators and representatives in congress that I do not favor any punitive actions or taxes on fossil fuels in the name of AGW, period. [emphasis added – MH]

    In fact, Lance has repeatedly responded to presentations of the peer-accepted empirical facts and descriptions of the physics explained at an elementary level by complaining of their length. I’m not sure why given I perceive no benefit is yielded employing obvious rhetorical fallacies like the red herring “screed”; especially within a forum of people who are not scientifically illiterate regarding climate change as we encounter in the above quote.

  7. #7 Erasmussimo
    June 5, 2010

    Lance, you write:

    A Google search of “Global warming” and “Hurricanes” returns 1,960,000 hits. The vast majority of them are scare stories or exaggerations based only on the sparse number of studies that support such a link while ignoring the many more that do not.

    I just carried out the same search, without quotes around the word Hurricanes, and I got 2,190,00 — the list seems to be growing fast! However, your statement regarding the content of these links is exactly the reverse of the case. Here are the first five links I got from Google and relevant quotes from them:
    “The latest understanding of hurricanes is that almost the opposite is true: storms may actually decline in frequency as the planet warms, even as they grow in strength.”

  8. #8 Erasmussimo
    June 5, 2010

    “It is premature to conclude that human activity–and particularly greenhouse warming–has already had a detectable impact on Atlantic hurricane activity. However, human activity may have already caused substantial changes that are either below the ‘detection threshhold’ or are not properly modeled yet (e.g., aerosol effects).”

  9. #9 Erasmussimo
    June 5, 2010

    [Makes no direct statement regarding the question of climate change’s effect on hurricanes, just quotes IPCC to the effect that overall precipitation rates will increase. There is a link to another page asking whether global warming caused Hurricane Katrina, where it states: “although we cannot be certain global warming intensified Katrina per se, it clearly has created circumstances under which powerful storms are more likely to occur at this point in history (and in the future) than they were in the past.”

  10. #10 Erasmussimo
    June 5, 2010

    “Numerous studies in recent years have found no evidence that the number of hurricanes and their northwest Pacific Ocean cousins, typhoons, is increasing because of the rise in global temperatures.

    But a new study in the journal Nature found that hurricanes and typhoons have become stronger and longer-lasting over the past 30 years. These upswings correlate with a rise in sea surface temperatures.”

  11. #11 Erasmussimo
    June 5, 2010

    {continued; this is the final entry made necessary by some unknown restriction in the site software},8599,1839281,00.html
    “are storms getting stronger, and if so, what’s causing it? According to a new paper in Nature, the answer is yes — and global warming seems to be the culprit. Researchers led by James Elsner, a meteorologist at Florida State University, analyzed satellite-derived data of tropical storms since 1981 and found that the maximum wind speeds of the strongest storms have increased significantly in the years since, with the most notable increases found in the North Atlantic and the northern Indian oceans. They believe that rising ocean temperatures — due to global warming — are one of the main causes behind that change.”

  12. #12 Pierce R. Butler
    June 9, 2010

    Are we really comfortable with even a small risk of leaving such a legacy for our offspring?

    Why not? We’ve already set them up for an inheritance of kilotons of high-level radwaste, persistent toxins in the food chain, collapsing oceanic ecosystems, a severely reduced species count, and at least two generations who will look back on really crappy music for their golden oldies.

  13. #13 Omegle
    February 4, 2011

    But a new study in the journal Nature found that hurricanes and typhoons have become stronger and longer-lasting over the past 30 years. These upswings correlate with a rise in sea surface temperatures.