Global Warming Intensified the Record Floods in Texas and Oklahoma

A paper just published in Geophysical Research Letters looked at the May 2015 floods in Texas and Oklahoma in the USA, which resulted from the wettest single month on record in both states.  The lead author, Dr. Wang from Utah State and his colleagues examined the role of strengthened El Niño teleconnections on the flood event. ...

Dr. Wang and his authors recognized that in a warming world, the way El Niño intensifies rainfall patterns would change.  That is, today’s El Niños may be more potent than prior El Niños.  In particular, they compared the El Niño influence from 1948–1980 with the influence after 1980.  They used a wide collection of measurements and modeling tools and concluded, 

The record precipitation that occurred over Texas and Oklahoma during the month of May 2015 was the results of a series of climate interactions and anomalies.  Foremost is the role that El Niño played.  A developing ENSO (El Niño/Southern Oscillation) has a tendency to increase spring precipitation over the southern Great Plains and this effect was found to have intensified since 1980; this intensification was concomitant with a warmer atmosphere due to anthropogenic (human) greenhouse gases. 

Specifically, the intensified ENSO teleconnection appears to be triggered by enhanced latent heat in the equatorial central Pacific, and is associated with a broad sea surface temperature warming in the tropics.  In essence, there was a detectable effect of anthropogenic global warming in the teleconnection and moisture transport leading to Mays 2015’s high precipitation.

Also worth noting is the potential for predicting extreme events like the Texas floods.  ENSO impacts are one of the few climate anomalies forecasters today have a better handle of.  This paper notes that the chance for Texas and Oklahoma to experience an abnormally wet season in May was predicted as early as in March, according to computer models used by the Climate Prediction Center.  What remains challenging is how scientists can anticipate the extraordinary magnitude of precipitation as fell in Texas and, if they do see it, how can the right information reach people.

The detection of human influence on extreme weather is a rapidly maturing field and each year we are finding more and more evidence of the connections.  The corollary is that without efforts to reduce greenhouse gases, we can expect more frequent and intense extreme weather in the future.

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