Global change in cloud radiative effect revealed in CERES observations

Abstract This study uses data from the Clouds and the Earth’s Radiant Energy System (CERES) to examine global changes in cloud radiative effect (CRE) for 2001–2022. Results show that the 22-year changes in shortwave (SW) CRE are generally opposite to those of longwave (LW) CRE, which shows that the change in net CRE is relatively weakened due to the offset of these two variables. However, significant changes in net CRE are found in some regions. Over the Arctic, the net CRE decreased by –0.8 W m⁻²/decade due to surface darkening caused by loss of snow and ice that outweighed the increase in cloud fraction (SW cooling effect of clouds intensified). Over the northeastern Pacific and northwestern Atlantic Oceans, strong increases in SW CRE occurred with decreasing cloud fraction. However, this did not lead to a significant change in the entire northern hemispheric mid-latitudes because it was offset by the decreased SW and LW CREs over China. Over the Tropics, the net CRE decreased slightly, by –0.1 W m⁻²/decade, due to the dominant decrease in LW CRE at 0–10° N in association with the decreasing cloud fraction and increasing water vapor (decreased LW warming effect of clouds). Over the southwestern Indian Ocean and southern Atlantic Ocean, the net CRE increased due to the decreasing cloud fraction (weakened SW cooling effect of clouds). These multi-decadal changes in CREs are not well-simulated in the current climate models, which may limit the accuracy of regional climate predictions.