The Dust Bowl
Between 1930 and 1940, the southwestern Great Plains region of the United States suffered a severe drought. Once a semi-arid grassland, the treeless plains became home to thousands of settlers when, in 1862, Congress passed the Homestead Act. Most of the settlers farmed their land or grazed cattle. The farmers plowed the prairie grasses and planted dry land wheat. As the demand for wheat products grew, cattle grazing was reduced, and millions more acres were plowed and planted.
Dry land farming on the Great Plains led to the systematic destruction of the prairie grasses. In the ranching regions, overgrazing also destroyed large areas of grassland. Gradually, the land was laid bare, and significant environmental damage began to occur. Among the natural elements, the strong winds of the region were particularly devastating.
With the onset of drought in 1930, the overfarmed and overgrazed land began to blow away. Winds whipped across the plains, raising billowing clouds of dust. The sky could darken for days, and even well-sealed homes could have a thick layer of dust on the furniture. In some places, the dust drifted like snow, covering farm buildings and houses. Nineteen states in the heartland of the United States became a vast dust bowl. With no chance of making a living, farm families abandoned their homes and land, fleeing westward to become migrant laborers.
By 1940, 2.5 million people had moved out of the Plains states, the largest migration in American history. Of those, 200,000 moved to California. The migrants were not only farmers, but also professionals, retailers, and others whose livelihoods were connected to the health of the farm communities. Many ended up competing for seasonal jobs picking crops at extremely low wages.
Imperial Valley changed its tune. Richest agricultural center in California and headquarters of the state's front-line reactionary defence, Imperial took one New Deal agency to its bosom. The Migratory Labor Camps, set up under the Farm Security Administration in 1937, won a real victory over the stupidity and wrath that made the Valley a sink-hole of farm labor exploitation since the days of the first irrigating ditch.
There were some eleven Migratory Labor Camps scattered through California, and their stories are pretty much the same. In the little town of Brawley, for example, over three hundred dust-bowl families were huddled together in a dry riverbed a few miles from town. . . . Despite the unbelievable misery in that riverbed, the good citizens of Imperial did nothing. A few half-humorously suggested that the "Okies" be lined up and shot: others sent half-hearted protests to the Health Department.
Then, one day in 1937, representatives of the Farm Security Administration walked into Brawley. Concluding an agreement for the purchase of a small plot of land at the edge of town, they drew up plans for tent platforms, an office building, a nursery and a medical unit, three sanitary units with showerbaths and toilets, a tool shed, a garage - in fact all that goes into the making of a rough but livable community. . . .
In his 1939 book The Grapes of Wrath, author John Steinbeck described the flight of families from the Dust Bowl: "And then the dispossessed were drawn west--from Kansas, Oklahoma, Texas, New Mexico; from Nevada and Arkansas, families, tribes, dusted out, tractored out. Car-loads, caravans, homeless and hungry; twenty thousand and fifty thousand and a hundred thousand and two hundred thousand.
They streamed over the mountains, hungry and restless--restless as ants, scurrying to find work to do--to lift, to push, to pick, to cut--anything, any burden to bear, for food. The kids are hungry. We got no place to live. Like ants scurrying for work, for food, and most of all for land." In all, 400,000 people left the Great Plains, victims of the combined action of severe drought and poor soil conservation practices.
The 1930s Dust Bowl drought had four drought events with no time to recover in between: 1930-31, 1934, 1936 and 1939-40. A 2014 study using a reconstruction of North American drought history over the last 1,000 years found that the drought of 1934 was the driest and most widespread of the last millennium.
Using a tree-ring-based drought record from the years 1000 to 2005 and modern records, scientists from NASA and Lamont-Doherty Earth Observatory found the 1934 drought was 30 percent more severe than the runner-up drought (in 1580) and extended across 71.6 percent of western North America. For comparison, the average extent of the 2012 drought was 59.7 percent.
"It was the worst by a large margin, falling pretty far outside the normal range of variability that we see in the record," said climate scientist Ben Cook at NASA's Goddard Institute for Space Studies in New York. Cook is lead author of the study, which will publish in the Oct. 17 edition of Geophysical Research Letters.
"We found that a lot of the drying that occurred in the spring time occurred downwind from where the dust storms originated," Cook said, "suggesting that it's actually the dust in the atmosphere that's driving at least some of the drying in the spring and really allowing this drought event to spread upwards into the central plains."
This type of high-pressure system is part of normal variation in the atmosphere, and whether or not it will appear in a given year is difficult to predict in computer models of the climate. Models are more attuned to droughts caused by La Niña's colder sea surface temperatures in the Pacific Ocean, which likely triggered the multi-year Dust Bowl drought throughout the 1930s. In a normal La Niña year, the Pacific Northwest receives more rain than usual and the southwestern states typically dry out.
But a comparison of weather data to models looking at La Niña effects showed that the rain-blocking high-pressure system in the winter of 1933-34 overrode the effects of La Niña for the western states. This dried out areas from northern California to the Rockies that otherwise might have been wetter. As winter ended, the high-pressure system shifted eastward, interfering with spring and summer rains that typically fall on the central plains. The dry conditions were exacerbated and spread even farther east by dust storms.
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