This hurricane brought to you by global warming?

September 12, 2008

You could say that hurricanes run in my family.  At my grandparents’ house in Galveston, Texas, there has always been a hurricane tracking chart hanging on the porch just outside the kitchen.  A big yellow map with the Caribbean and Gulf of Mexico, you could place little black magnets on it to track where each hurricane was going.  And I remember there being quite a few little magnets on it each summer.  My grandmother was born on Galveston Island, as was my father, and my grandfather lived there almost all of his life.   There are lots of legends about strong hurricanes in their past: where they nailed shut the windows and did, or more frequently didn’t, evacuate.

Happy to report that with Hurricane Ike approaching Galveston even as we speak, my grandparents, aunts, uncles and cousins are not there.  But Ike is putting a little wrinkle in my travel plans: I’m supposed to fly to Houston on Sunday morning, en route to Austin to visit my parents.  So far the flight is not cancelled, but I suspect there’s a strong chance that I’ll be leaving Monday instead of Sunday. Discussing these travel plans with my father on the phone yesterday, we commented on just how many strong hurricanes seem to be hanging around the Gulf of Mexico this year, and I made an off-hand comment that global climate change was taking its toll.   But this morning I started wondering whether that was really true: were there more hurricanes now than in the past, and if so, was this to do with global warming?

Being the nerdy social scientist that I am, I spent some time downloading hurricane data from 1900 to 2008, and then analysing it.  This data doesn’t say anything in and of itself about the impact of global climate change on hurricanes (because I haven’t looked at what’s causing hurricanes), but there are some interesting trends to note.   From 1900 to 2008, there was an average of just over five classifiable hurricanes (hurricanes are measured on a scale from 1 to 5 based on the strength of their winds, with 5 being the strongest) in the Atlantic ocean.  The year with the most number of hurricanes (a whopping 15) was 2005, the year that Hurricane Katrina destroyed New Orleans and much of the Gulf Coast of the US.  But years with 10 or more hurricanes are interspersed throughout the data set: 1916, 1933, 1950, 1969 (a stormy year by most metrics), 1995 and 1998.

There have been many more hurricanes from 1950 to 2008 than there were from 1900 to 1950 (352 vs. 223) and those storms have also been stronger: there were 80 category 4 and 5 storms from 1950 to the present, but only 38 from 1900 to 1950.  But this trend has not been consistent: the 1970s and 80s had relatively few strong storms in comparison to either the previous period (the 50s and 60s) or the following period (the 90s and beyond).

The data is inconclusive: there are ways to read increases in the number and strength of hurricanes as globalisation has progressed, and ways to interpret it as a random pattern of hurricane number and strength.  In fact, National Geographic has said the same thing: while there is a plausible reason that global warming would cause more hurricanes (warmer air and water causes more storms), and some new studies have shown increasing strength based on increase in sea temperatures, the great majority of studies “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.”

So there jury is still out as to whether this hurricane is brought to you by global warming.  But it’s sure putting a kink in my globalised life style.


One Response to “This hurricane brought to you by global warming?”

  1. […] of my aunt and uncles’ house, is sitting under almost 2 feet of water.   They are insured: hurricanes happen, even large devastating ones like this one.  Like the mayor of Galveston said yesterday “The […]

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