Monday, January 19, 2009

NASA Explains the Dust Bowl Drought

Agriculture has been the base of all past civilizations and remains so today, a fact we forget at our peril.
We do forget though, partly because as economies develop people become estranged from the land. Here's a gross example- the U.S. farm population was over 90% of the total at the time of the first census (1790) and is now under 2%.

As an aside, the USDA performs the Census of Agriculture every five years, the results of the 2007 survey will be released February 4, 2009, here's the site for the 2002 census.

I point out ag's importance because it is one of those "You don't know what you've got 'til it's gone", "out of sight out of mind" types of infrastructure that is going to force itself into our consciousness in the next couple decades.

The return of the Pacific Decadal Oscillation (PDO) to its cool phase and the current warm phase of the Atlantic Multidecadal Oscillation (AMO) are going to make North American agriculture less dependable going forward. Here's a quote from our May 6, 2008 post "A Black Swan in Food":
...Donald Coxe, chief strategist of Harris Investment Management and one of my favorite analysts, spoke at my recent Strategic Investment Conference. He shared a statistic that has given me pause for concern as I watch food prices shoot up all over the world.

North America has experienced great weather for the last 18 consecutive years, which, combined with other improvements in agriculture, has resulted in abundant crops. According to Don, you have to go back 800 years to find a period of such favorable weather for so long a time....
Here are the tables of monthly values for the AMO and the PDO. One quick note, the El Nino-Southern Oscillation (ENSO) is distinct from the PDO but the PDO cool phase appears to correlate with a 2:1 La Nina/El Nino ratio whereas the warm phase correlates with twice as many El Nino's. Here is the current Oceanic Nino Index.
From NASA:

March 18, 2004 - (date of web publication)


NASA scientists have an explanation for one of the worst climatic events in the history of the United States, the "Dust Bowl" drought, which devastated the Great Plains and all but dried up an already depressed American economy in the 1930's.

Dust bowl image from the 1930's

Item 1

Dust storm approaching Stratford, Texas. (Credit: NOAA Photo Library, Historic NWS collection)
More dust bowl images

Siegfried Schubert of NASA's Goddard Space Flight Center, Greenbelt, Md., and colleagues used a computer model developed with modern-era satellite data to look at the climate over the past 100 years. The study found cooler than normal tropical Pacific Ocean surface temperatures combined with warmer tropical Atlantic Ocean temperatures to create conditions in the atmosphere that turned America's breadbasket into a dust bowl from 1931 to 1939. The team's data is in this week's Science magazine.

These changes in sea surface temperatures created shifts in the large-scale weather patterns and low level winds that reduced the normal supply of moisture from the Gulf of Mexico and inhibited rainfall throughout the Great Plains.

Data modeling to see dust bowl

Item 2

NASA Model Simulation: See side bar for more information. (Credit: NASA)
Click HERE to see animation.

"The 1930s drought was the major climatic event in the nation's history," Schubert said. "Just beginning to understand what occurred is really critical to understanding future droughts and the links to global climate change issues we're experiencing today.">>>MUCH MORE