For nearly two decades, satellites have monitored how sunlight and heat move through Earth’s atmosphere. Now, new NASA research suggests the planet is becoming darker — with the Northern Hemisphere absorbing more energy than the Southern.
The study, based on 24 years of data from NASA’s Clouds and the Earth’s Radiant Energy System (CERES), found that the Northern Hemisphere gained 0.34 watts per square metre more solar energy per decade than the South.
While that may sound small, scientists say it’s significant enough to disrupt global wind patterns, ocean currents and temperatures.
Dr Norman G. Loeb, lead author and climate scientist at NASA’s Langley Research Center, said both hemispheres are reflecting less sunlight, “but the effect is stronger in the North.”
The darkening is driven by the loss of reflective surfaces — melting Arctic ice and snow expose darker ground and ocean, which absorb more heat.
Reduced aerosol pollution has also played a role. While cleaner air benefits health, it reflects less sunlight back into space, further intensifying the imbalance.
Natural events in the South, like Australia’s bushfires and the Hunga Tonga eruption, briefly increased reflection, but not enough to offset the Northern Hemisphere’s gains.
This asymmetry could alter weather systems and strengthen warming in Europe, North America and Asia. “Even modest differences in energy balance can have profound implications,” the researchers warn, noting that clouds are failing to fully compensate for the imbalance.
Scientists are now extending satellite monitoring to understand whether this shift is temporary or marks a long-term change in Earth’s energy system — one that could reshape climate models and intensify regional warming across the globe.
