Earth Is Getting Darker, Literally, and Scientists Are Trying To Find Out Why

An anonymous reader shares a report: It's not the vibes; Earth is literally getting darker. Scientists have discovered that our planet has been reflecting less light in both hemispheres, with a more pronounced darkening in the Northern hemisphere, according to a study published on Monday in Proceedings of the National Academy of Sciences. The new trend upends longstanding symmetry in the surface albedo, or reflectivity, of the Northern and Southern hemispheres. In other words, clouds circulate in a way that equalizes hemispheric differences, such as the uneven distribution of land, so that the albedos roughly match -- though nobody knows why. "There are all kinds of things that people have noticed in observations and simulations that tend to suggest that you have this hemispheric symmetry as a kind of fundamental property of the climate system, but nobody's really come up with a theoretical framework or explanation for it," said Norman Loeb, a physical scientist at NASA's Langley Research Center, who led the new study. "It's always been something that we've observed, but we haven't really explained it fully." To study this mystery, Loeb and his colleagues analyzed 24 years of observations captured since 2000 by the Clouds and the Earth's Radiant Energy System (CERES), a network of instruments placed on several NOAA and NASA satellites. Instead of an explanation for the strange symmetry, the results revealed an emerging asymmetry in hemispheric albedo; though both hemispheres are darkening, the Northern hemisphere shows more pronounced changes which challenges "the hypothesis that hemispheric symmetry in albedo is a fundamental property of Earth," according to the study.

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