May 1, 2008
Columbia Scientists Warn of Modern-Day
Dust Bowls in Vulnerable Regions
Farming transformed a natural drought into
an extreme disaster—and may do so again
Climate scientists using computer models to simulate the 1930s Dust Bowl that devastated the U.S. Great Plains region have found that dust caused by farming activities probably amplified a natural drop in rainfall, turning a normal drying cycle into a widespread agricultural collapse. The Columbia University researchers state that the findings raise concerns that ongoing pressures on farmland from population growth and climate change could worsen the current global food crises by leading to similar extreme events in other vulnerable 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 Pacific—so-called La Niña 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.
The La Niña of the 1930s was different—and so extreme—because it was coupled with the arrival of farmers into 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, leading to increased levels of dust.