Here Comes the Atlantic Hurricane Season

Mon, 2011-08-08 08:33Chris Mooney
Chris Mooney's picture

Here Comes the Atlantic Hurricane Season

gulf of mexico sea surface temperatures

This has been a year of dramatic disasters and weather extremes. From tornadoes to droughts to heat waves, the U.S. has been battered.

Unfortunately, the hurricane season that’s about to get firing may not go any easier on us.

Nobody can say in advance where storms are form to strike or whether they are going to make landfall—but everything is lining up for there to be a lot of them in the Atlantic region, and some very strong ones. As you can see from the figure here, we’re just starting the climb towards the peak of the season, which occurs on September 10.

Sea surface temperatures in the main development region for Atlantic hurricanes (pictured above for the Gulf) are the third hottest they’ve been on record. Everything is lining up for there to be a lot of action: 9-10 hurricanes, and 3-5 major ones, NOAA predicts. There have already been 5 tropical storms, but that’s child’s play compared with what’s likely coming.

I have already written about the difficulty of pinning tornado disasters on global warming. And by the same token, I’ve written about why it’s perfectly justifiable to draw climate links for heat waves and declining Arctic sea ice.

Where do hurricanes fit into this picture? That’s tricky—but something worth discussing now, because if there’s a major U.S. land-falling hurricane, everybody is going to be asking about it, just as they always do.

The hurricane story is in some ways more straightforward than the tornado one, but still beset by uncertainty. We have clear theoretical reasons to expect the strongest storms to get stronger, and to rain more—a potentially devastating, but often neglected, aspect of a hurricane’s impact.

In other words, there is every reason to expect that, as we continue our ill-advised experiment with the Earth’s climate, we will indeed reap some devastating whirlwinds.

However, that’s the future rather than the present. Scientists aren’t sure we can yet separate the signal of hurricane intensification from the noise of natural variability—and what’s more, they now also expect total storm numbers to decrease overall, a significant offsetting effect to the expectation of greater intensity. Here’s a consensus statement from last year, by the leaders of this field:

Whether the characteristics of tropical cyclones have changed or will change in a warming climate — and if so, how — has been the subject of considerable investigation, often with conflicting results. Large amplitude fluctuations in the frequency and intensity of tropical cyclones greatly complicate both the detection of long-term trends and their attribution to rising levels of atmospheric greenhouse gases. Trend detection is further impeded by substantial limitations in the availability and quality of global historical records of tropical cyclones. Therefore, it remains uncertain whether past changes in tropical cyclone activity have exceeded the variability expected from natural causes. However, 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. For all cyclone parameters, projected changes for individual basins show large variations between different modelling studies.

Further explanation is provided by NOAA’s Tom Knutson, who states that in his latest modeling study, overall hurricane numbers are expected to decrease in the Atlantic, but at the same time, the frequency of the most intense hurricanes could as much as double by the end of the century. So less storms overall, but also more very devastating ones.

What does this mean for the current hurricane season, forecast to be very active?

Not all that much. Atlantic storms have been very busy since 1995, but scientists still aren’t willing to unequivocally state that global warming is the reason–even if they may suspect an influence.

So in a bad storm year, or with a bad storm landfall, you don’t want to claim that global warming “caused” that season, that storm, or that landfall. Global warming is always operating in the background, and contributing to everything that happens. But there are myriad other factors and variables—like wind steering currents—that also direct how storms form and behave.

Rather, you say this: We’ve seen, again and again, the devastating power of hurricanes. Why anyone would want to mess with the climate system, when an even greater frequency of the worst storms is expected to result, is difficult to fathom.

Previous Comments

“Why anyone would want to mess with the climate system, when an even greater frequency of the worst storms is expected to result, is difficult to fathom.”

Amen to that. All we can do is hope and pray for this to be the most devastating, destructive and deadly hurricane season in human history. The more death and destruction the better, that way we can more easily claim its caused by driving SUVs. Wahoo! Cheers

True! very well said..

Is Al Gore going to swear like that on national tv on the day of his “Climate Reality” thing??? I hope not!

c.a.t. and rum: Exhibit A and B, above, for why this blog should simply ban miscreants who are here merely to throw s**t against the wall, instead of having something worthwhile to contribute.

as charged. just think its so funny that your leader is truly insane and just wanted to make sure when you get your marching orders that you knew what state of mind he is in.

It’s Al’s last chance to grab some support for the CAGW fiasco. He needs our support and I hope you all will be there for him!

If only there were some sort of… “natural mechanism” to explain variations in the earth’s temperature.

Such a hypothetical source would have be large, though: On the magnitude of our own sun.

During the past 6-years since Hurricane Katrina, global tropical cyclone frequency and energy have decreased dramatically, and are currently at near-historical record lows.

According to a new peer-reviewed research paper accepted to be published, only 69 tropical storms were observed globally during 2010, the fewest in almost 40-years of reliable records.

Furthermore, when each storm’s intensity and duration were taken into account, the total global tropical cyclone accumulated energy (ACE) was found to have fallen by half to the lowest level since 1977.

Peer Reviewed:

Shut up, denier evilist!

We can reasonably infer, from various coupled GCM ensemble simulations, that this is not significantly inconsistent with what we might expect to see, possibly due to the varying feedback characteristics indicative of anthropogenic warming, which are very likely to occur from time to time.

Learn some science, teabagger!

hahahahahah. you really can put those thoughts in writing?! what wouldnt indicate agw to you? really, name me something that would indicate to you that agw is non existent….btw, andy revkin just bit the texas dust. he has done it before so you still have some hope that people will take him away for a while and ‘re-educate’ him but for now you have lost one of your biggest cheerleaders. but i digress….what isn’t ” significantly inconsistent with what we might expect to see” ?

but while i am waiting….just thought it was even funnier (sadder)that in an article by mooney talking about our ‘experiment with our climate’ there is reason to believe that we may be making storms wetter, fiercer and more common etc. Then we have a comment by johnny2 showing how storms are NOT wetter and more common etc and EEB comes along to tell us to learn some science and says “from various coupled GCM ensemble simulations, that this is not significantly inconsistent with what we might expect to see” !!!!!!! right here in the same article and comments this guy has the balls to critisize our science understanding. so which is it EEB, more storms or less storms? hint: mooney says more, you say less (by way of a GCM ensemble no less). priceless

You know, it’s times like these that I think maybe I should stop being such a wiseguy and start behaving more facetiouslessly.

Nice one, sir.

Historic lows are consistant with CAGW climate predictions. Since everything has been predicted up to now, everything is consistant with predictions. Even a broken clock is correct at least once per day. Cheers

The great thing about mitigating CO2 production is that because of our heroic work soon there will be no more Katrinas. Because we control the weather. Its just that simple.

Its a lot more fun stopping hurricanes and tornadoes than being a pawn of corporate blood lust like all those denier types.

It cooler today than it was yesterday. My efforts are paying off already!

so, you think that more heat in the oceans, land and air, coupled with more water vapor in the air won’t have any effect on the intensity of storms?

You might as well just staple a piece of cardboard with “Moron” written on it to your forehead.

Ocean warming stopped in 2003. The Ocean has not warmed since.

Peer Reviewed:

he is just a dead drummer so he can inore facts

Ginger Baker the drummer is not dead. Just another of your ‘facts’, I suppose.

Oceans not warming? Must be a miracle, right?

Or not:

no I changed teams - Im not a scientist - Im just an ex pawn of kochacola brothers and all them.

What we need in the anti co2 squad is more celebrity endorsements of our anti co2 lifestyle. Im thinking sports guys like Steve Nash.

True, very well said.

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