Every time there’s a massive weather event — like Hurricane Sandy affecting much of the East Coast early this week — climatologists are called upon to answer the question of whether this weather is evidence of global warming. And while most would say an individual weather event cannot attributed as evidence of global warming, the link is still being made.
In fact, some climate scientists are taking a closer look at individual weather events and making an effort to quantify climate change’s role in contributing to it.
Although trends in changing climate are generally tracked over years, not just by the weather outside your window, as it’s often put, NPR’s Adam Frank reported several researchers are looking at various aspects of individual weather events and the influence of climate change:
Researchers like Randall Dole of NOAA, for example, might ask what percentage of an extreme event’s magnitude came from a changing climate. Peter Stott of the UK Met Office frames the question differently. He looks at the odds for a given extreme weather event to occur given human-driven climate change. Kevin Trenberth of NCAR takes a third view, asking: Given a changed background climate, how should we expect weather to change?
Earlier this year with the extreme heat wave across much of the country and “derecho” affecting the D.C.-metro area, scientists likened these events to what would be expected with climate change, although they said it was too soon to attribute it to this. Around the same time a report was released that said global warming was at least turning the odds to favor the likelihood of extreme weather events.
Andrew Revkin for the New York Times Dot Earth Blog wrote some scientists think Sandy specifically is “what you’d expect following a summer in which much of the Arctic Ocean was open water.” Arctic sea ice saw a record melt this year. Revkin did write that there is still “far too much natural variability in the frequency and potency of rare and powerful storms,” like Sandy, to say anything beyond that it is what would be expected with climate change projections.
Revkin contacted climate scientists to see what they thought of Hurricane Sandy as it pertained to global climate change. Here are a few excerpts of what they wrote — and they don’t all agree:
- Jennifer Francis, Rutgers University: “The jet stream patter […] is exactly the sort of highly amplified (i.e., wavy) pattern that I’d expect to see more of in response to ice loss and enhanced Arctic warming. […] It could very well be that general warming along with high sea-surface temperatures have lengthened the tropical storm season, making it more likely that a Sandy could form, travel so far north, and have an opportunity to interact with a deep jet-stream trough associated with the strong block, which is steering it westward into the mid-Atlantic.”
- Martin Hoerling, NOAA: “As to underlying causes, neither the frequency of tropical or extratropical cyclones over the North Atlantic are projected to appreciably change due to climate change, nor have there been indications of a change in their statistical behavior over this region in recent decades (see IPCC 2012 SREX report). So, while it will rain like “black cats and Frankenweenies” over the midatlantic, this is not some spell conjured upon us by great external forces….unless you believe in the monster flicks of Universal Stuidios fame!”
- Kevin Trenberth, National Center for Atmospheric Research: “The sea surface temperatures along the coast are 5 degrees F. or more above average and 1 degree F. is from global warming. Stronger storm and more precipitation results. But with respect to the Arctic connection, I don’t believe it.”
- Patrick J. Michaels, climatologist with ties to the Cato Institute: “It’s also consistent with a planet with colder temperatures as well as one with warmer ones. More important, events like this are inevitable on a planet that has an ocean with the geography of the Atlantic (meaning a Gulf Stream-like feature), a large north-south continent on its western margin without a transverse mountain range to inhibit the merger of tropical warmth with polar cold, and four seasons in the temperate latitudes. And I predict confidently that we will survive Sandy, which should not be a tropical cyclone at landfall.”
Even as some scientists are continuing to draw links between global warming and extreme weather events though, as Frank reported for NPR, hurricanes are rather low on the list of weather that scientists believe they can study to draw links to climate change. He wrote that scientists “don’t have the tools to make strong inferences” about hurricanes and climate change.