Associating natural disasters with climate change — like some did last week with the massive tornado that touched down in Oklahoma — is a distortion that has been rattling around for nearly a decade or longer.
The most glaring example may be Al Gore’s portrayal of Hurricane Katrina in his 2006 film An Inconvenient Truth. According to Gore, the hurricane was the outcome of unchecked anthropogenic greenhouse gas emissions and a harbinger of what’s to come.
But he was quickly called out for misrepresenting the science to gain support for his cause. And as the dust settled in Oklahoma, it became clear that 1) the situation sucked, and 2) the science is still out on whether or not there is a concrete connection between global warming and these monster storms.
J. Marshall Shepherd, a climate change expert and professor at the University of Georgia was quoted in a May 22 CNN story as saying:
Trends in tornado occurrence over the last 50 years do not appear to have changed in conjunction with more greenhouse gases in the atmosphere and patterns of rising temperatures. … There is currently a much better understanding of how climate change increases the risks of droughts, heat waves and precipitation. There are also indications that changing patterns may influence the intensity of hurricanes. But as far as tornadoes: There’s just not a lot of information. (“No evidence global warming spawned twister”)
Marshall was echoing a 2012 Intergovernmental Panel on Climate Change special report [SREX] on managing the risks of extreme events, which notes that:
- There is low confidence in observed trends in small spatial-scale phenomena such as tornadoes and hail…
- There is low confidence in any observed long-term (i.e., 40 years or more) increases in tropical cyclone activity (i.e. intensity, frequency, duration) …
- There is medium confidence that some regions of the world have experienced more intense and longer droughts, in particular in southern Europe and West Africa, but in some regions droughts have become less frequent, less intense, or shorter, for example, in central North America and northwestern Australia.
- There is limited to medium evidence available to assess climate-driven observed changes in the magnitude and frequency of floods at regional scales because the available instrumental records of floods at gauge stations are limited in space and time, and because of confounding effects of changes in land use and engineering.