According to a new study published in the journal Geophysical Research Letters, warming ocean waters have caused a drop in the brightness of the earth.
Researchers measure the earth’s albedo by observing the light reflected from earth that illuminates the surface of the moon as well as with satellite measurements. The earth reflects about 30% of the sunlight that shines on it. The data shows that the earth now reflects about half a percent less light than it did 20 years ago, with most of the drop occurring in the last three years. That number had been fairly constant for most of the past 20 years.
According to the researchers at the New Jersey Institute of Technology, New York University, and a Spanish astrophysical agency, the apparent cause of the albedo drop has been a reduction of bright, reflective low-lying clouds over the eastern Pacific Ocean in most recent years. That is the same area off the west coasts of North and South America where increases in sea surface temperature have been observed because of the reversal of a climate condition called the Pacific Decadal Oscillation, which is likely a result of global climate change.
The dimming of the earth implies that more solar energy is being absorbed rather than reflected, which may contribute further to global warming.
These results are somewhat surprising. Scientists had postulated that the warming of the earth could lead to more clouds and therefore a higher albedo – more reflection of the sun’s light. If that were the case, it would help to moderate warming and balance the climate system. These new results indicate that the opposite is true.
Photo, posted August 18, 2021, courtesy of Arek Socha/GPA Photo Archive via Flickr.