The strange symmetry between Earth’s Northern and Southern Hemispheres appears to be breaking… The Northern Hemisphere is absorbing more sunlight than the South.
Many years ago, scientists noticed something strange: Earth’s Northern and Southern Hemispheres reflect almost the same amount of sunlight back into space.
The reason the symmetry is strange is because the Northern Hemisphere has more land, cities, pollution, and industrial aerosols. All of these things should lead to a higher albedo—more sunlight reflected than absorbed. On the other hand, the Southern Hemisphere is mostly ocean, which is darker and absorbs more sunlight.
However, in a recent study in Proceedings of the National Academy of Sciences of the United States of America (PNAS), satellite data revealed that That symmetry is breaking.
As detailed by , scientists analyzed 24 years (between 2001 and 2024) of observations from the mission Clouds and the Earth’s Radiant Energy System (CERES) and NASA.
It turned out that the Northern Hemisphere is getting darker faster than the Southern Hemisphere. In other words, it is absorbing more sunlight.
That change can alter weather patternsprecipitation and global climate in the coming decades.
Breaking it down, the team found that the Northern Hemisphere is absorbing about 0.34 watts more solar energy per square meter per decade than the Southern Hemisphere.
“It may not seem like a big difference, but across the planet, it’s a huge number,” he explained to Live Science. Zhangqing Lia climate scientist at the University of Maryland who was not part of the study.
To understand what was causing this imbalance, scientists applied a technique called partial radiative perturbation (PRP) analysis. The PRP method separates the influence of factors such as clouds, aerosols, surface brightness and water vapor in calculating the amount of sunlight each hemisphere absorbs.
The results showed three main reasons for the dimming of the Northern Hemisphere: melting snow and ice, decreasing air pollution and increasing water vapor.
“It made perfect sense,” he said. Norman Loeba climate scientist at NASA’s Langley Research Center who led the study.
“The surface of the Northern Hemisphere is becoming darker because the snow and ice are melting. This exposes the land and ocean underneath. And pollution has decreased in places like China, the United States and Europe. It means there are fewer aerosols in the air to reflect sunlight. In the Southern Hemisphere, it is the opposite”, he explained.
“As the north is warming faster, it also retains more water vapor. water vapor does not reflect sunlight, it absorbs it. That’s another reason why the Northern Hemisphere is receiving more heat,” he added.
