Cloud cover changes are a “top-down dynamical driver” of Earth’s climate.

A July 2026 Environmental Research Letters paper authored by Bellocchi et al. attributes ~80% of the rise in Earth’s absorbed solar radiation since 2000 to declining high-reflectivity cloud cover, primarily from circulation-driven contraction of storm-cloud zones.

The study highlights the climate’s “albedo governance,” suggesting a 1% shift in Earth’s albedo corresponds to a 1°C surface temperature change.

With more cloud cover, more solar radiation is reflected and the surface cools. With declining cloud albedo, which has been observed since 1980, less solar radiation is reflected and the surface warms.

Cloud cover changes are driven by natural atmospheric circulation modes and internal variability. This is supported by reconstruction data showing cloud cover decline has for centuries occurred independently from “greenhouse-gas forcing.”

Image Source: Bellochi et al., 2026