Number of Natural Disasters Up Four-Fold over Last Two Decades: Global Warming to Blame?

2005 atlantic hurricane season
Image courtesy of NASA

A newly released Oxfam report is blaming global warming for the four-fold increase in the number of weather-related natural disasters - primarily floods and storms - in the last two decades, alleging that the number has jumped from about 120 per year during the 1980s to roughly 500 per year now. These disasters have exerted a disproportionate impact on the world's poorest, the report goes on to say, affecting "more than 250 million people" in South Asia, Africa and Mexico this year alone.

This figure itself represents a 70% increase above average 1985 - 1994 levels, when about 174 million people were affected by natural disasters. Appealing to the U.N.'s members ahead of the Convention on Climate Change in Bali, Oxfam director Barbara Stocking warned that "humanitarian assistance will be overwhelmed and recent advances in human development will go into reverse," unless immediate action was taken.In the wake of Cyclone Sidr and its already heavy death toll, there is no arguing Stocking's point that more needs to be done to provide relief and help avert future humanitarian disasters in developing countries. Where we would quibble with Oxfam's report, however, lies in the following statement: "Rising greenhouse gas emissions are the major cause of weather-related disasters and must be tackled."

Now while it's certainly true that the rise in the number of natural disasters over the past two decades has correlated with the increase in greenhouse gas emissions, claiming a causative relation between the two is misguided. As was observed by the astute writers of RealClimate in the weeks following Hurricane Katrina:

"It is impossible to know whether or not this event would have taken place if we had not increased the concentration of greenhouse gases in the atmosphere as much as we have. Weather events will always result from a combination of deterministic factors (including greenhouse gas forcing or slow natural cycles) and stochastic factors (pure chance)."

This larger point was also aptly put across by the science writer Chris Mooney in his latest book, Storm World, in which he (uncategorically) declared at the outset that: "Global warming did not cause Hurricane Katrina, or any other weather disaster. Or to put it more precisely, we just can't say scientifically that global warming either does or does not "cause" individual weather events."

In other words, while it's fair to say that global warming likely contributed to the intensification of storms - by heating up the oceans' surface waters - to say that it definitively caused events like Hurricane Katrina or Cyclone Sidr to occur is just wrong. You're simply dealing with too many variables and outside factors to draw a direct connection.

So while we commend the spirit of Oxfam's report - its insistence on the provision of more aid to those hardest hit by natural disasters - we'd prefer it if they didn't tweak the science to suit their needs.

Via ::Agence France-Presse: Natural disasters have quadrupled in two decades (news website)

See also: ::Katrina and Rita Responsible for Nation's Worst Ever Forestry Disaster, ::"Business As Usual Not Acceptable": Groups Aim To Increase Women's Participation in Climate Change

Tags: Africa | Bali | Mexico | Natural Disasters | United Nations


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