![]() Specifically, there has been a reduction of bright, reflective low-lying clouds over the eastern Pacific Ocean in the most recent years, according to satellite measurements made as part of NASA’s Clouds and the Earth’s Radiant Energy System (CERES) project. The changes in Earth’s albedo observed by the researchers did not correlate with periodic changes in the Sun’s brightness, so that means changes in Earth’s reflectiveness are caused by something on the Earth. Two things affect the net sunlight reaching the Earth: the Sun’s brightness and the planet’s reflectivity. When the latest data were added to the previous years, the dimming trend became clear. “The albedo drop was such a surprise to us when we analyzed the last three years of data after 17 years of nearly flat albedo,” said Philip Goode, a researcher at New Jersey Institute of Technology and the lead author of the new study, referring to the earthshine data from 1998 to 2017 gathered by the Big Bear Solar Observatory in Southern California. Average error bars for CERES measurements are of the order of 0.2 W/m 2. A best fit line to the CERES data (2001–2019) is shown with a blue dashed line. The CERES annual albedo 2001–2019 are shown in blue. Earthshine annual mean albedo 1998–2017 expressed as watts per square meter (W/m 2).
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