The amount of sunlight reaching the Earth’s surface has been variable for decades now, and a new study supports the idea that human activity is to blame.
In the late 1980s, researchers first noticed a steady decline or ‘diminution’ in the Earth’s brightness in various parts of the world, including a nearly 30 percent drop in sunlight from the sun. 1950s over a specific area in the Soviet Union.
Just a few decades later, after the banning of the most harmful aerosols and the dissolution of the Soviet Union, the movement suddenly shifted from a “global mitigation” effect to a clear one.
There has long been a suspicion that a granular substance, such as aerosol sulfate, will form in the atmosphere that will block sunlight from entering. Evidence has shown that this type of pollution reflects almost all the radiation it encounters in the atmosphere, as well as being exposed to or absorbing light.
Whether or not these grains are responsible for decades of global mitigation remains controversial, and some argue that natural variables, such as the inclusion of clouds of sunlight, are factors greater than pollution in the amount of light that reaches the Earth.
This new study attempted to account for changes in sunlight under cloudy clear conditions and found that man-made pollution is, in fact, a major cause of mitigation.
Wild and his colleagues used historical data collected between 1947 and 2017 with Potsdam’s solar radiation record. The Potsdam record is considered one of the longest and best maintained continuous measurements of solar radiation on the Earth’s surface.
Even when skies are clear from the clouds, the analysis reveals that there can be strong relaxing and clear movements, similar to cloudy skies.
“Our analysis shows that strong decadal differences (dimming and illumination) not only appear when considering clouds, but also become apparent under cloudless conditions when eliminate the effects of clouds, ”the authors write in their published paper.
With clouds regulated, the authors argue that changes in aerosolization must be a major change in global warming and illumination.
“Although we had already accepted it, we have not been able to confirm it directly so far,” said climate scientist and lead author of the study Martin Wild.
It would be nice to think that global mitigation is no longer a problem, but just because the world is shining, does not mean that we have the future.
Recently, some internationally banned aerosols have begun to rise in secret, and even if we find those under control scientists are concerned that historical mitigation has already helped by hiding some of the effects of global warming.
It is not necessary for more sunlight to pour into the planet, they warn; it could make ‘Earth’s hothouse’ warmer.
That is partly why some experts are exploring ways to promote global mitigation through solar geoengineering, while others think that is far too risky.
A recent study, for example, linked heavy mining practices to regional mitigation, and found that it had reduced tree growth since the 1970s.
Forests are one of the most important carbon sinks on Earth, and if the growth of trees with less sunlight slows down to such an extent, we could be seriously burning ourselves in the foot.
Clearly there is no easy solution, but this new research suggests that we took the problem for granted.
The study was published in the Geophysical Research Letters.