Global Warming = Worsening Hurricanes? Wrong, So Far

Friday, I had lunch with a friend and she brought up the topic of global warming. She said, "I'll bet your (meteorology) meetings are contentious!" I laughed and said one contentious meeting had made the front page of the Wall Street Journal in 2006. I retrieved the article (which can be read here) and sent it to her.

As I was re-reading the article, I ran across this:

William Gray, America's most prominent hurricane scientist and an ardent foe of the belief that global warming has worsened hurricanes, was supposed to join a panel discussing the storms. So was Greg Holland of the National Center on Atmospheric Research -- who disagrees with Dr. Gray. But the organizers withdrew the invitations after deciding the dispute had grown so nasty it was too risky to put the two in the same room...

His adversary Dr. Holland is among a group of prominent scientists who argue that the recent burst of powerful storms isn't part of a normal pattern. In a recent article, he and co-authors said that global warming caused by human activity, while not affecting the number of hurricanes, appears to be causing more of them to be very intense. Dr. Holland went to the meeting despite the cancellation of his joint appearance with Dr. Gray and presented his paper's conclusions during a session on a wide variety of weather issues.

The dispute over worsening hurricane intensity got personal as the article explains.

In the wake of the record 2005 season, the question was important:

What is going on with hurricanes like Katrina and the subsequent Wilma, which was the strongest ever recorded in the Atlantic, matters urgently to millions of people wondering whether coastal areas are safe. Insurers and other companies are trying to calculate future risks of operating in the vulnerable regions. And policy makers are wrestling with whether to rebuild some shattered communities.

We are about three-quarters of the way through the seventh hurricane season since that article was published. Who was correct? Those that said hurricanes are worsening or those who said hurricane intensity is not connected to global warming?

The short answer is Dr. Gray. Hurricanes have lessened since the 2005 season.  

But, I want to give a more detailed answer because I believe the details are important.

One could say that the hypothesis, "warmer temperatures = worsening hurricanes" has not been tested because global warming stopped in 1998. Temperatures certainly have not warmed since the 2005 hurricane season.

World temperatures for the last twenty years. Credit: Hadley Center, England.

Yes, in spite of all of the forecasts to the contrary, global warming has stopped. It might start again, I have no prediction to offer in that regard.

But, regardless of atmospheric temperatures, the trend in hurricane and tropical storm activity is flat to down. I have placed an arrow pointing to the 2005 season:

From Dr. Ryan Maue, click to enlarge

Below is the trend in the total energy of tropical storms and hurricanes worldwide (top values) and in the northern hemisphere (bottom values):

Here, the peak in energy of the 2005 season sticks out like a sore thumb. But, instead of rising as just about everyone but Dr. Gray predicted, it fell.

In fact, the United States has gone the longest interval since records have been kept -- back to the 1800's -- without a major hurricane (category 3, 4 or 5) striking our shore: 2,531 days! Every day that passes adds another day to that record. The old record was 2,231 days which ran from 1900 to 1906.

Current data indicates there is nothing presently in the tropics that would be able to stop the streak.

To summarize:

• Global warming has stopped, at least for the time being
• World and northern hemisphere hurricanes have lessened rather than worsened, in spite of forecasts to the contrary
• The United States, every day, continues to lengthen an ongoing record for the longest interval without a major hurricane

Again, when compared to the real world, the global warming prophets of doom could not have been more wrong. 

And, a number of people owe Dr. Gray an apology.