The Dynamics Of Dust: Uncovering Its Role In Current And Future Climate Breakdown
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The major impacts of a warming climate are well known: hotter temperatures, more — and more intense — storms, melting glaciers and sea ice, drier climates in many regions and wetter weather in others. But some researchers say one major element of climate change is being overlooked: dust. Dust plays a fundamental role in the world’s ecological processes, and the dynamics of dust are changing as the climate changes.
Although the issue is poorly studied, it’s clear that dust dynamics are shifting in two main ways. Humans are the main cause of an increasing amount of dust in the atmosphere. As farming, grazing, and other development in places such as the Horn of Africa or the U.S. Southwest spread deeper into arid regions, vegetation is destroyed, exposing the soil to wind erosion. In addition, increasing drought due to a warming climate is a major cause of the dust problem, as it kills vegetation and uncaps the soil, allowing it to become windborne.
This has both positive and negative effects. More dust, for example, means more nutrients and minerals, such as iron, are being transported long distances, which stimulates the growth of oceanic plankton — an essential link in the marine food chain. But increasing quantities of dust could cause serious problems for parts of the world, from decreased water flow in some mountain regions to increased human exposure to dust-borne pathogens, a growing health concern.
In the United States, the 2017 National Climate Assessment found that warmer temperatures are reducing soil moisture in parts of the West, and also predicts more drought in the coming years. These factors kill vegetation that keeps soil in place and have already led to more dust storms. And winds that blow in from the Pacific Ocean are increasing as ocean temperatures heat up. That, in turn, draws in drier north winds that suck moisture out of the soil in the southwestern U.S. The frequency of dust storms there has more than doubled since the 1990s — from 20 per year to 48 in the 2000s — and will likely continue to increase, according to one study. On the other side of the world, weather patterns in some regions have shifted in a different way. Rainfall in the Sahara has increased because of warmer ocean temperatures, which has meant less dust blowing westward across the Atlantic Ocean. Dust storms have also declined in the deserts of China and South America and are projected to be lower in the Great Plains of the U.S. — all because of an increase in precipitation that stimulates plant growth, which caps the soil.
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http://e360.yale.edu/features/climate-connection-unraveling-the-surprising-ecology-of-dust