We have to talk about Harvey

We can't say with any certainty that hurricane Harvey which produced extraordinary rain across Houston a few days ago was caused by climate change.  What we can say, though, is that it was made much worse by climate change.

The science of  attributing extreme weather to climate change is complicated and developing every day. Here’s a guide of what we know about the links between climate change and Harvey to help unpack the elements that contributed to this historic and unfolding storm. 

As seas warm, more water evaporates to the atmosphere. A warmer atmosphere can hold more water, fueling extreme rainfall and increasing flood risk. Record-breaking rainfall is a classic signature of climate change, and the fingerprint of climate change has been firmly identified in the observed global trend of increasing extreme precipitation.

Many areas of Southeast Texas have received rain so extreme that historical data indicates it should only happen once every 1,000 years.

 Houston is experiencing its third ‘500-year’ flood in 3 years. 

 Since the 1950s, Houston has seen a 167 percent increase in the frequency of the most intense downpours. 

 A rain gauge in Mont Belvieu, about 40 miles east of Houston, registered 51.88 inches of rain through late afternoon Tuesday. Once verified, this amount would break not only the Texas state rainfall record but also the record for the remaining Lower 48 states.

 A formal attribution study of last year’s historic flood in Louisiana found that climate change to date had most likely doubled the frequency of the extreme rainfall that drove that flood.

Kevin Trenberth, a senior scientist at the U.S. National Center for Atmospheric Research, said, “The human contribution can be up to 30 percent or so of the total rainfall coming out of the storm.”

Another major contributor to the extreme rainfall totals was that Harvey stalled for many days over southeast Texas. Waves in the jet stream can stall in place (instead of moving eastward), leading to blocking and persistent weather patterns that fuel the intensity and duration of rainfall events.

• A study from March 2017 found that climate change is altering large scale weather patterns, such as the jet stream, which have the ability to dramatically amplify extreme weather events, such as extreme rainfall, during the summer.

• According to Michael Mann, the stalled weather pattern during Hurricane Harvey “is precisely the sort of pattern we expect because of climate change.”

[Read more here]

There's more in the piece by Climate Code Red and if you get a chance you should read it.

We are making progress towards a zero carbon economy.  But not fast enough.

See also:

Warming linked to Storm Harvey devastation
South Asia floods kill 1,200 and shut 1.8 million children out of school
In an era of dire climate records the US and South Asia floods won't be the last
So Let’s Talk About the Science of How Climate Change Kicked Harvey into Higher Gear
Why are the crucial questions about Hurricane Harvey not being asked?