NEW YORK April 30, 2008 Climate scientists using computer models to simulate the 1930s Dust Bowl on the U.S Great Plains have found that dust raised by farmers probably amplified and spread a natural drop in rainfall, turning an ordinary drying cycle into an agricultural collapse. The researcher say the study raises concern that current pressures on farmland from population growth and climate change could worsen current food crises by leading to similar events in other regions.
Recent studies indicate that periodic droughts in the western United States are controlled by naturally occurring periods of cool sea-surface water temperatures over the eastern tropical Pacificso-called La Nia phases. Via long-distance winds, these phases indirectly affect faraway rain patterns. In addition to the 1930s, such patterns have occurred in the 1850-60s, 1870s, 1890s, 1950s, and 1999 to present.
What made the 1930s different was the arrival of farmers onto the Great Plains, where they replaced drought-resistant wild prairie grasses with fragile wheat, neglected to plant cover crops in unused fields, and allowed livestock to overgraze pastures.
When the 1932-1939 drought struck, plants shriveled and ever more bare soil was exposed. The land was quickly eroded by gigantic dust storms, and farming collapsed. Skies were chronically darkened on and off; in some years, an estimated 770 million metric tons of topsoil were lost, and over the whole time, 3.5 million people were displaced--one of the 20th centurys worst environmental disasters. The new study finds that farm dust probably fed the disaster, doubling the drop in rainfall, and moving the drought itself northward into major farming regions.
The researchers, based at Lamont-Doherty Earth Observatory and NASA Goddard Institute for Space Studies (both affiliates of Columbia Universitys Earth Institute) used a computer model to simulate a 1930s drought driven only by t
|Contact: Kevin Krajick|
The Earth Institute at Columbia University