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Hurricanes ARE getting Stronger — Thanks to Global Warming!

By Joe Romm

"Hurricanes ARE getting Stronger — Thanks to Global Warming!"


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Global warming has long been predicted to make hurricanes more intense. Well, now we are seeing more intense hurricanes. Chris Mooney has a great post on the recent storm surge of category 5 hurricanes now that Felix has joined that once-elite club. He notes:

Some people, especially the Deniers, think this is all a coincidence, or the result of incomplete data from earlier years. Here’s why I don’t:


Global warming increases sea surface temperatures (SSTs), which are directly correlated with stronger storms. Indeed, tropical cyclones are threshold events–if sea surface temperatures are below 80°F (26.5°C), they do not form.

Some analysis even suggests there is a sea surface temperature threshold close to 83°F needed for the spawning major hurricanes. Global warming may actually cause some hurricanes and some major hurricanes to develop that otherwise would not have (by raising sea surface temperatures above the necessary threshold at the right place or time). This is especially true in the Atlantic, where sea surface temperatures appear to be closer to the threshold than other hurricane-forming basins.

Equally important, one of the ways that hurricanes are weakened is the upwelling of colder, deeper water due to the hurricane’s own violent action. But if the deeper water is also warm, it doesn’t weaken the hurricane. In fact, it may continue to intensify. Global warming heats both the sea surface and the deep water, thus creating ideal conditions for a hurricane to survive and thrive in its long journey from tropical depression to Category Four or Five superstorm.

I have a longer discussion of this in Hell and High Water — and a good non-technical article can be found here. The bottom line is that we would expect global warming to increase the number of category 5 storms. Indeed a 2004 modeling study concluded:

One implication of the results is that if the frequency of tropical cyclones remains the same over the coming century, a greenhouse gas–induced warming may lead to a gradually increasing risk in the occurrence of highly destructive category-5 storms.

So the fact that we are seeing such an increase is no surprise.

Yes, it could all be a grand coincidence or the result of inadequate data — but as a scientist I apply Occam’s Razor. We have data that matches our theory. The simplest explanation is that the theory is right.

As NASA’s James Hansen put it in an important 2007 analysis,to the degree that hurricane intensification of the past decade is a product of increasing SST in the Atlantic Ocean and the Gulf of Mexico, human-made GHGs probably are a substantial contributor.”

One final point: I am aware that the 2004 modeling study predicted it would be many decades before we saw the warming signal in hurricane intensity trends. You can take that as a sign that the data is wrong, if you want, but as I noted in this post — Are Scientists Overestimating — or Underestimating — Climate Change, Part I — scientists have underestimated recent sea ice loss, ice sheet mass loss, temperature rise, sea level rise, and expansion of the tropics.

So I conclude a more likely explanation is that the models are systematically underestimating key climate cycle feedbacks and omitting crucial factors that will accelerate the pace of climate change beyond what the IPCC “consensus” believes.

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7 Responses to Hurricanes ARE getting Stronger — Thanks to Global Warming!

  1. Good, meaty post, Joe. If you cop to science at all, this is as close to common sense as it gets. Damn obvious cause and effect along with an element of chance. We’re lucky, for example, that Nature is being relatively gentle and landing these Cat 5s in thinly populated areas.

  2. Hippygeerl93 says:

    i have nightmares about huricanes and tornados! when will the goverment start cooling down the weather again, we need some laws about polluting!

  3. Dr_Bob says:

    Not sure how accurate this report is but I found it quite interesting:http://www.csmonitor.com/2004/0913/p01s03-usgn.html

    “He notes that since 1995, only 1 out of 7 major hurricanes spawned in the Atlantic have made landfall in the US, compared with the 100-year average of 1 in 3″.

    Looks like with the recent hurricanes in hitting the US things are just “averaging” out. Could this be the same for a lot of other GW happenings? Is mother nature just “averaging” out?

  4. Dr_Bob says:


    Here is an opinion that we are seeing far less violent storms than those previously recorded….

  5. Joe says:

    Uhh, yeah, but only because there was “super heated” water from an asteroid hitting the planet. Global warming won’t make a planet that hot, but it will make things much hotter than they are now, suggesting hurricanes will only get more intense.

    Nature doesn’t “average” out — it follows the laws of physics and statistics. And, in any case, we are overriding nature now, but taking all the carbon captured over millions of years and releasing it in a period of decades.

  6. Dr_Bob says:

    Fair comment but if looking at the “stats” just for the last few hundred years it would seem that nothing much has changed as far as hurricanes go.

    When were hurricanes first classified according to their strength?
    Are they classified purely on their wind speeds?

    Wouldn’t we have a better record of hurricanes if we changed the classification ie instead of going up to a max of 5 we could go up to a max of 10?
    If Katrina was a 5 then on the new scale it would still be a 5. We would then be able to quickly ascertain if they are getting stronger/more violent. What I am trying to get at is that historically we have had “stronger” than 5 but all the 5′s get lumped together….(hope that all makes some sense!)

  7. With two years following your post among the lowest for hurricane activity I would think you would be feeling a little silly by now.

    Maybe you should give up sipping from the scaremongers cup.