Extreme Temperature Diary- Saturday April 18th, 2020/Main Topic: Megadrought In Southwestern U.S. Becoming More Likely

Saturday April 18th… Dear Diary. The main purpose of this ongoing blog will be to track United States extreme or record temperatures related to climate change. Any reports I see of ETs will be listed below the main topic of the day. I’ll refer to extreme or record temperatures as ETs (not extraterrestrials).😉

Main Topic: Megadrought In Southwestern U.S. Becoming More Likely

Dear Diary. As many of my former associates from the Weather Channel know, I was very interested in weather patterns that led to short term drought and heat waves during the 1980s until the time I left in 2014. My interest led me to accept global warming theory and now fact much earlier than most of my co-workers during the late 1980s. Eyeballing 500 millibar charts, I noticed that geopotential heights were slowly rising with time in the 1980s and 1990s such that hotter conditions were occurring during those decades across the continental U.S. in general. Also, ridges tended to build first in the Southwest and hang out there longer than in other areas of the country, particularly in the summer months. The Southwest, naturally, was mostly arid and has always been so since the first Indians inhabited North America millennia ago.

In the last couple of decades the southwestern U.S. has become much more susceptible to long term drought, lasting as many as five years during the 2010s. It has been no surprise to me that new studies indicate that the Southwest is in danger of falling into a civilization, life altering long term drought soon. Inside Climate News has just reported on the latest study:


The Parched West is Heading Into a Global Warming-Fueled Megadrought That Could Last for Centuries

Warmer temperatures and shifting storm tracks are drying up vast stretches of land in North and South America.

By Bob Berwyn, InsideClimate News

Apr 16, 2020

A sign referencing the drought is posted next to a fallow field on April 24, 2015 in Lemoore, California. Credit: Justin Sullivan/Getty Images
A sign referencing the drought is posted next to a fallow field on April 24, 2015 in Lemoore, California. Credit: Justin Sullivan/Getty Images

The American West is well on its way into one of the worst megadroughts on record, a new study warns, a dry period that could last for centuries and spread from Oregon and Montana, through the Four Corners and into West Texas and northern Mexico.

Several other megadroughts, generally defined as dry periods that last 20 years or more, have been documented in the West going back to about 800 A.D. In the study, the researchers, using an extensive tree-ring history, compared recent climate data with conditions during the historic megadroughts. 

They found that in this century, global warming is tipping the climate scale toward an unwelcome rerun, with dry conditions persisting far longer than at any other time since Europeans colonized and developed the region. The study was published online Thursday and appears in the April 17 issue of the journal Science. 

Human-caused global warming is responsible for about half the severity of the emerging megadrought in western North America, said Jason Smerdon, a Columbia University climate researcher and a co-author of the new research. 

“What we’ve identified as the culprit is the increased drying from the warming. The reality is that the drying from global warming is going to continue,” he said. “We’re on a trajectory in keeping with the worst megadroughts of the past millennia.”

The ancient droughts in the West were caused by natural climate cycles that shifted the path of snow and rainstorms. But human-caused global warming is responsible for about 47 percent of the severity of the 21st century drought by sucking moisture out of the soil and plants, the study found. 

The regional drought caused by global warming is plain to see throughout the West in the United States. River flows are dwindling, reservoirs holding years worth of water supplies for cities and farms have emptied faster than a bathtub through an open drain, bugs and fires have destroyed millions of acres of forests, and dangerous dust storms are on the rise. 

(Please read the rest of this linked fine article.)

I’ve also noticed in my record research that by far the most number of new record temperature reports are coming from Southern California, Nevada, and Arizona. The cities of Los Angeles, Las Vegas and Phoenix set new daily records just about every season. I may start a new record count project to see how ratios stack up there compared with the country as a whole. Stay tuned for that.

Now here are some of today’s articles and notes on the horrid COVID-19 pandemic:

Here is more climate and weather news from Saturday:

(As usual, this will be a fluid post in which more information gets added during the day as it crosses my radar, crediting all who have put it on-line. Items will be archived on this site for posterity. In most instances click on the pictures of each tweet to see each article.)

(If you like these posts and my work please contribute via the PayPal widget, which has recently been added to this site. Thanks in advance for any support.) 

Guy Walton “The Climate Guy”

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