Lauren Gold in Cornell University Chronicle: … The amount of dust in the Earth's atmosphere has doubled over the last century, according to a new study; and the dramatic increase is influencing climate and ecology around the world. The study, led by Natalie Mahowald, associate professor of earth and atmospheric sciences, used available data and computer modeling to estimate the amount of desert dust, or soil particles in the atmosphere, throughout the 20th century. It's the first study to trace the fluctuation of a natural (not human-caused) aerosol around the globe over the course of a century.….Desert dust and climate influence each other directly and indirectly through a host of intertwined systems. Dust limits the amount of solar radiation that reaches the Earth, for example, a factor that could mask the warming effects of increasing atmospheric carbon dioxide. It also can influence clouds and precipitation, leading to droughts; which, in turn, leads to desertification and more dust. Ocean chemistry is also intricately involved. Dust is a major source of iron, which is vital for plankton and other organisms that draw carbon out of the atmosphere.
…Among their results, the researchers found that regional changes in temperature and precipitation caused a global reduction in terrestrial carbon uptake of 6 parts per million (ppm) over the 20th century. The model also showed that dust deposited in oceans increased carbon uptake from the atmosphere by 6 percent, or 4 ppm, over the same time period.
While the majority of research related to aerosol impacts on climate is focused on anthropogenic aerosols (those directly emitted by humans through combustion), Mahowald said, the study highlights the important role of natural aerosols as well. "Now we finally have some information on how the desert dust is fluctuating. This has a really big impact for the understanding of climate sensitivity," she said….
Graphic from the Cornell website
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