Overview

• The NASA-led analysis, published in PNAS, uses 24 years of CERES observations to show a statistically significant hemispheric asymmetry in reflected solar radiation.
• The divergence is quantified at roughly 0.34 watts per square meter per decade, with overall planetary reflectivity decreasing and the Northern Hemisphere dimming faster than the Southern Hemisphere.
• Authors link the shift to Arctic snow and sea-ice loss, declining reflective aerosols in the north, episodic aerosol boosts in the south from events like Australia’s fires and the Hunga Tonga eruption, and cloud behavior that has not compensated.
• During 2020–2024, the Northern Hemisphere absorbed about 0.54 W/m² more shortwave energy than the Southern Hemisphere, highlighting a recent intensification of the imbalance.
• The study warns the trend could influence major circulation and rainfall patterns, including shifts in the Intertropical Convergence Zone and possible ocean-current changes, while emphasizing uncertainties given the relatively short record.