Tuesday, August 29, 2017

Climate change? Bah humbug!

In November-December of 2015, record rain fell in Chennai.  After visiting the city during the winter break, I wrote in an op-ed:
While scientists are cautious when postulating the cause-and-effect relationship, the role of climate change has not been ruled out. ...
Of course, the natural disaster was amplified by mismanagement of the land and water. Homes and high-rise buildings had been constructed at a frenzied pace in what were previously water-drainage areas, marshlands and lake beds. Thus, the floodwaters speeding along the natural contours of the land ended up in basement garages and ground floor units.
It feels like deja vu all over again, when I follow the horrific updates from Houston.

David Leonhardt writes in the (not failing) NY Times:
Obviously, some extreme weather events are unrelated to climate change. But a growing number appear to be related, including many involving torrential rain, thanks to the warmer seas and air.
“The heaviest rainfall events have become heavier and more frequent, and the amount of rain falling on the heaviest rain days has also increased,” as the National Climate Assessment, a federal report, found. “The mechanism driving these changes,” the report explained, is hotter air stemming from “human-caused warming.”
Leonhardt adds this:
In Houston’s particular case, a lack of zoning laws has led to an explosion of building, which further worsens flooding. The city added 24 percent more pavement between 1996 and 2011, according to Samuel Brody of Texas A&M, and Houston wasn’t exactly light on pavement in 1996. Pavement, unlike soil, fails to absorb water.
Add up the evidence, and it overwhelmingly suggests that human activity has helped create the ferocity of Harvey.
Houston became Chennai on an even larger scale!

The climate scientist, Michael Mann, who helped us understand the famous hockey-stick graph, is emphatic: "climate change made Hurricane Harvey more deadly."
There is a simple thermodynamic relationship known as the Clausius-Clapeyron equation that tells us there is a roughly 3% increase in average atmospheric moisture content for each 0.5C of warming. Sea surface temperatures in the area where Harvey intensified were 0.5-1C warmer than current-day average temperatures, which translates to 1-1.5C warmer than “average” temperatures a few decades ago. That means 3-5% more moisture in the atmosphere.
That large amount of moisture creates the potential for much greater rainfalls and greater flooding. The combination of coastal flooding and heavy rainfall is responsible for the devastating flooding that Houston is experiencing.
Mann continues about the stalling, which has made Harvey pour water from the skies.  This stalling is not only with hurricanes and cyclones though:
 More tenuous, but possibly relevant still, is the fact that very persistent, nearly “stationary” summer weather patterns of this sort, where weather anomalies (both high-pressure dry hot regions and low-pressure stormy/rainy regions) stay locked in place for many days at a time, appears to be favoured by human-caused climate change. We recently published a paper in the academic journal Scientific Reports on this phenomenon.
Hot days are hotter than ever and stay hot for a lot longer.  Wet days are wetter than ever and stay wet for a lot longer.

In another op-ed, after the devastating cyclone that tore through Chennai, I wrote in January 2017:
Such extremes are consistent with climate weirding. ...
Climate scientists warn that we have to prepare for more and more extreme events that result from climate weirding. The Intergovernmental Panel on Climate Change noted that “a changing climate leads to changes in the frequency, intensity, spatial extent, duration and timing of extreme weather and climate events, and can result in unprecedented extreme weather and climate events.”
Of course, it is not merely about the rains. Heat waves, too, for instance, are increasing in both frequency and intensity. Unlike wind and rains, heat waves are not action-made for cameras — heat waves produce no images and videos that go viral. But heat waves kill more people than rains and cold spells do.
In that op-ed, I suggested that we Americans look at ourselves in the mirror:
We in the United States need to stop denying the human cause in the global climatic changes in this industrial era. As a country with an affluence that is the envy of the rest of the world, we need to assume leadership in addressing global weirding.
These will be enormous challenges during a Trump presidency and with a Republican-controlled Congress.
The 63 million who voted for trump and his climate-change-denying minions can now add Houston to the growing list for why they stand accused.

Source

2 comments:

Ramesh said...

For the moment, all I can do is feel for the people of Houston. All the pictures and reports show an awful situation. Most hurricanes come and go - Harvey seems to be staying in the area and lashing day after day.

It looks that everybody is pulling for each other and I hope every American comes together to help those who have lost everything. This is a time to open the hearts large and wide.

Sriram Khé said...

I am sure you will have a lot to say about the next post :(