A new NASA-backed study has found that the Northern Hemisphere is getting darker than the Southern Hemisphere, and this could have serious consequences for global climate. Using data from the CERES (Clouds and the Earth’s Radiant Energy System) satellite, scientists found that the Northern Hemisphere is losing more radiant energy than the Southern Hemisphere, meaning it’s absorbing more sunlight and reflecting less. From space, it would appear noticeably dimmer.

This imbalance affects Earth’s “radiation budget,” the amount of light the planet absorbs and radiates back into space. Normally, the oceans help balance this by transporting heat between the hemispheres, but in the past two decades, this ability has weakened.

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One of the main factors is the reduction in albedo, or the reflectivity of the Earth’s surface. The rapid melting of Arctic ice is replacing reflective ice and snow with more heat-absorbing land and water, accelerating the warming of the poles, which is now four times faster than in other parts of the globe.

Another source of reflectivity is clouds, which have been declining, especially low-lying ones. Ironically, this can be linked to the reduction in pollution in the Northern Hemisphere: polluting particles (aerosols) served as the “seeds” for cloud formation, and their absence means fewer clouds. In 2024, NOAA reported that reduced emissions from shipping are also reducing “ship marks,” reflective clouds that help cool the Earth.

Meanwhile, the Southern Hemisphere has been exposed to natural injections of aerosols, such as the fires in Australia and the eruption of the Hunga Tonga volcano. The difference between the hemispheres is increasing by 0.34 watts per square meter every decade, enough to significantly affect climate models and make it difficult to predict the planet’s future.