Dry climates prevailed worldwide during Ice Ages because so much of earth’s atmospheric moisture was locked into massive Ice Sheets. Less precipitation meant less vegetative cover, and with fewer plant roots holding soil into place, the strong winds, also caused by Ice Sheet expansion, blew dirt and sand great distances. Some settled into huge sand dunes; other particles were blown all over the planet into the oceans and as far north as Greenland. Scientists take ice cores from the 125,000-year-old glacier in Greenland, and they have a year-by-year diary of past climatic conditions. Rings from summer melting mark the years exactly. Oxygen isotope ratios from air bubbles trapped inside the annual rings help scientists determine past average annual temperatures, but they also can determine how dry the climate was based on the quantity of dust and sand from inside each annual ring. The quantity of dust particles deposited was highest during the dryest years of the Ice Age.
Pleistocene sandstorms were fatal to the animals and plants buried under the dust. Animals that escaped these massive storms still suffered, perhaps fatally from getting the dust in their lungs. These sandstorms benefitted Pacific Ocean ecosystems because iron from sediment blown into the ocean fed phytoplankton, the base of the food chain. Scientists think most of the minerals came from the Gobi Desert which expanded during Ice Ages. Some recent studies suggest dust storms in Europe were even larger when they occurred during late winter and early spring. In North America, especially along the Mississippi River, waterways shrank, and exposed riverine sands blew into large dunes, still visible today.
Sand blown from the Gobi Desert during Ice Ages fertilized the Pacific Ocean.
Windblown sediment from the edge of Ice Age glaciers and exposed riverine sand blew into huge dunes still visible today.
Map showing where windblown sediment deposited from melting glaciers settled. This sediment is known as loess.
This diagram shows how dust particles were deposited into the Greenland Ice Sheet. The ice core rings are an annual diary of climate going back 125,000 years.
These are the types of minerals found in ice cores. Iron-rich minerals fertilized oceans.
The best facsimile of these ancient dust storms from the historical record occurred during the Dust Bowl era of the 1930’s. The ravages of World War I reduced Russian and European production of wheat. American farmers took advantage of the high wheat prices and ploughed over all the prairie grasses in order to plant as much wheat as possible, and at first they thrived because they planted during an unusually wet weather cycle. Starting in 1930 several years of severe drought shriveled all the plants, leaving thousands of square miles bare of any vegetation. High winds blew this dried out soil as far east as the Atlantic Coast. In the dust bowl area including Oklahoma, Texas, New Mexico, Kansas, Nebraska, and Colorado; the dust was so thick it covered houses, cars, and livestock. Many of the farmers left, leading to the famous Okie migration to California. In response to this disaster the government used the Civilian Conservation Corps to plant 200 million trees and created the Great Plains Shelter Belt. The government also advised famers to use better farming techniques such as contour ploughing (perpendicular to hills) and crop rotation to reduce soil erosion. Some programs even pay farmers not to plant–a socialist policy modern conservative farmers still use, demonstrating their political hypocrisy.
Main area of the 1930’s dust bowl disaster.
Poor farming practices led to this scary disaster.
The dust covered everything and caused health problems. The dried-out soil carried diseases and pesticides that made people suffer from long term health problems.
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