Broken glass yields clues to climate change

Jasper Kok in the University Corporation for Atmospheric Research News: Clues to future climate may be found in the way that an ordinary drinking glass shatters. A study appearing this week in Proceedings of the National Academy of Sciences finds that microscopic particles of dust, emitted into the atmosphere when dirt breaks apart, follow similar fragment patterns to broken glass and other brittle objects. The research, by National Center for Atmospheric Research (NCAR) scientist Jasper Kok, suggests there are several times more dust particles in the atmosphere than previously thought, since shattered dirt appears to produce an unexpectedly high number of large dust fragments.

The finding has implications for understanding future climate change because dust plays a significant role in controlling the amount of solar energy in the atmosphere. Depending on their size and other characteristics, some dust particles reflect solar energy and cool the planet, while others trap energy as heat. “As small as they are, conglomerates of dust particles in soils behave the same way on impact as a glass dropped on a kitchen floor,” Kok says. “Knowing this pattern can help us put together a clearer picture of what our future climate will look like.”

…Kok’s research indicates that the ratio of silt particles to clay particles is two to eight times greater than represented in climate models. Since climate scientists carefully calibrate the models to simulate the actual number of clay particles in the atmosphere, the paper suggests that models most likely err when it comes to the number of silt particles. Most of these larger particles swirl in the atmosphere within about 1,000 miles of desert regions, so adjusting their quantity in computer models should generate better projections of future climate in desert regions, such as the southwestern United States and northern Africa.

…The study results also suggest that marine ecosystems, which draw down carbon dioxide from the atmosphere, may receive substantially more iron from airborne particles than previously estimated. The iron enhances biological activity, benefiting ocean food chains, including plants that take up carbon during photosynthesis….

Dust particles in the atmosphere range from about 0.1 microns to 50 microns in diameter (microns are also known as micrometers, abbreviated as µm). The size of dust particles determines how they affect climate and weather, influencing the amount of solar energy in the global atmosphere as well as the formation of clouds and precipitation in more dust-prone regions. The NASA satellite image in this illustration shows a 1992 dust storm over the Red Sea and Saudi Arabia. (Composite illustration ©UCAR. This image is freely available for media use. Please credit the University Corporation for Atmospheric Research