This is a posting from 2011 about extreme weather. Obviously, this is an appropriate topic this winter. Since writing this several years ago, I have come to see all weather as taking place in a human altered climate. Thus, the appropriate question is not whether a particular event such as Superstorm Sandy was caused by climate change, but instead to understand those characteristics of the event that have been altered by climate change. For Katrina such an association is not particularly compelling, although the sea surface temperatures in the Gulf were very high. For Superstorm Sandy, there are several characteristics that may be linked to human caused climate change.
When I speak about climate change I always remind my audiences to not conflate climate with weather. For example, Katrina is best seen as an extreme weather event that cannot be mechanistically linked to anthropogenic climate change. Even scientists, including me, can lapse into sloppy thinking about individual weather events and declare, as I did in the heat of the moment, that events like Katrina are the smoking gun of human-caused climate change. Nonsense. Although I am embarrassed by my early lack of rigor, this mistake provided me with an important opportunity to study the stochastic nature of weather and its linkage to ongoing climate change. The term stochastic means that a weather event such as Katrina is driven by both deterministic and random factors. To be sure, Katrina was perhaps indicative of the kind of storm that modelers think will be increasingly typical of storms in the Anthropocene. As an…
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The Environmental Century 