From space, our planet has long been seen as a system in a delicate balance. However, a new NASA project now reveals a change: Earth is darkening.
According to data collected for over two decades by the NASA’s CERES (Clouds and the Earth’s Radiant Energy System) project, Earth is now absorbing more solar radiation instead of reflecting it.
But the real surprise is that this change is not uniform, as the project discovered an inversion in the energy balance of the planet.
Initial CERES data showed that the south was gaining an extra 0.20 watts per square meter (W/m²) each decade. However, since 2020, that trend has sharply reversed.
Now, the land is darkening more on the other side. Currently, the northern hemisphere is trapping more energy, with a surplus of 0.54 W/m² more than the south each decade.
This figure, although small, represents a huge energy imbalance on a planetary scale that accumulates year after year.
Unveiled enigmas: What is “albedo symmetry”?
This discovery breaks the assumption that Earth had a mysterious “perfect symmetry“, an enigma that has puzzled scientists for decades.
Despite their huge differences, the northern and southern hemispheres reflected exactly the same amount of solar light. This is known as “albedo symmetry“.
This balance was a mystery. This is because the northern hemisphere, with much more landmass, should have been different from the south. The latter is dominated by dark oceans that absorb more heat.
Scientists theorized that other factors, such as clouds and industry-generated pollution, were creating a delicate and perhaps artificial balance.
However, precise satellite data from the last two decades show that this balance is breaking. Furthermore, Earth is darkening more on one side: what does this mean.
Why did the luminous “symmetry” change and Earth darkens more in the north
Although hard to believe, specialists believe that one of the causes of this change is explained by an environmental victory. Ironically, the reduction of air pollution in industrialized countries could explain this novelty.
Despite being harmful, the tiny particles generated by pollution (known as aerosols) are very reflective and helped bounce solar light back into space.
With the decrease in pollution in regions like China, the United States, and Europe, less solar light is reflected. This causes the surface to absorb more energy.
This is explained by Norman G. Loeb, principal investigator of the CERES project at NASA: “It highlights the decrease in aerosols in the northern hemisphere due to the reduction of pollution in China, the United States, and Europe”.
Additionally, the specialist adds a second factor: “The increase in melting of snow and ice, which was faster in the northern hemisphere than in the south”.
As snow and ice (highly reflective surfaces) are replaced by the dark water of the ocean, the planet loses part of its reflective shield. This effect is much less pronounced in the south. This is because Antarctica is also losing ice, but at a much slower rate, retaining much of its albedo.
The northern hemisphere is darkening: implications
So, what does this change in the luminous balance of Earth imply? Despite arising from good news -less pollution from aerosols– it is still believed that this imbalance is accelerating global warming in the northern hemisphere.
The surplus of 0.54 W/m² of energy that the north is absorbing above the south is causing global warming to become more pronounced and accelerated in the north.
This change is already having observable effects, such as alterations in precipitation patterns and in atmospheric and oceanic circulation.
It is even causing a shift northward of the Intertropical Convergence Zone. This is “a belt around
