What’s the Deal with Extreme Weather and Climate Change? Union Of Concerned Scientists Explains

Yesterday the Union of Concerned Scientists (UCS) released an explanatory brief on the relationship between climate change and extreme weather events, saying "strong scientific evidence links climate change with increasing heat waves, coastal flooding, and other extreme weather events."

The issues has become a hot topic recently after a tornado ripped through Moore, Oklahoma, causing brutal damage and killing 24 people, 8 of which were children. Politicians linking the disaster to global warming were called "hard-hearted and factually ignorant vultures" by Forbes contributor James Taylor.

Although the practice of linking extreme weather events to accelerating global warming has become common place after the devastation of Hurricane Sandy topped off 2012, a record-breaking year for weather related droughts and wildfires. The storm reportedly broke the "climate silence" leading into the 2012 presidential election and ushered the warming atmosphere back into the spotlight.

Yet, says the UCS, the relationship between increased levels of greenhouse gasses in the atmosphere and apocalyptic weather is one best treated with caution. While some storms may have a more direct relationship with hotter summers, for example, other weather events, like tornados, are more tricky to blame on global warming, although "climate change [is] expected to play a role."

Here is a handy infographic that shows just where the strongest evidence lies:

Here is how they outline the particulars:

Extreme Weather and Climate Change

•   What's the connection between global warming and extreme weather? When it comes to heat waves and coastal flooding, the scientific evidence is clear: Human-caused climate change is increasing these extreme weather events.
•   Other forms of severe weather are also closely linked to climate change, including a rise in extreme precipitation events in some regions and increasingly severe droughts in others. 
•   The effect of climate change on tornadoes and hurricanes is an active area of research. Scientific confidence with observed data is currently low, though the underlying mechanisms of climate change are expected to play a role.

The infographic is based on research and evaluation coming from the Special Report on managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaption (SREX), from the latest Intergovernmental Panel on Climate Change assessment in 2012.

More information about the methodology behind the infographic can be found at the UCS explanatory note.

As Andrew Revkin reported, the UCS also released this statement to the press:

"We recently noticed a small flurry of policymaker statements on climate change that struck us as inaccurate or misleading. At the same time, we’ve received several inquiries about extreme weather, particularly in the wake of the Oklahoma tornado strike. Below, we’ve compiled some of the statements as well as blog posts and other resources that point to what the science says. Please let us know if you have any questions and if we can help identify other scientific resources.

When it comes to extreme weather, we always take the opportunity to point back to the last definitive international scientific report on extreme weather and climate change, which found strong historic links for heat waves, coastal flooding and changes in precipitation along with weaker links for tornadoes and hurricanes.

On Monday, Gov. Christie was asked for the second time in recent months if Superstorm Sandy was linked to climate change. The governor correctly said that Sandy was not “caused” by climate change, but he failed to acknowledge how sea-level rise, which is caused by climate change, increased the size of Sandy’s devastating storm surge. As the state rebuilds, it’s not clear if the governor is integrating future sea-level rise into his plans. Meanwhile, Rutgers University researchers estimate that the state can expect 1.3 feet of sea-level rise by 2050 and 3.1 feet by 2100.

Also on Monday, Sen. Sheldon Whitehouse (D-R.I.) included tornadoes in his discussion of extreme weather and climate change. At the time, his office says, he did not know tornadoes were hitting Oklahoma. Sen. Barbara Boxer (D-Calif.) also linked a number of extreme weather phenomena to climate change in a floor speech, including tornadoes. UCS climate scientist Brenda Ekwurzel writes that because the historical tornado record is spotty, scientists don’t yet have enough evidence to determine how climate change is affecting tornadoes.

Finally, Rep. Lamar Smith (R-Texas), chairman of the House Science Committee, used a Washington Post op-ed to spread increasingly common misinformation about recent surface temperature trends. In another blog post, Ekwurzel explains how natural variability and human-induced climate change are increasing global temperatures in a step-wise pattern."

Image Credit: Eric Nguyen via NASA