Warm ocean waters causing Earth's brightness to drop, says study

A new study has found that Earth's brightness is dimming due to warming ocean waters, courtesy of global warming. The study revealed that our planet is reflecting around 0.5 watt less light per square meter than it did 20 years ago.

The study was published in the journal Geophysical Research Letters and for the calculations, used decades of measurements of earthshine. Earthshine is the light that reflects from the Earth, which illuminates the moon.

In addition to earthshine, researchers also examined satellite measurements which proved that there is a major drop in Earth's reflectance/albedo, in the past 20 years. A major drop occurred in the last three years of earthshine data.

Researchers said that this is equal to a 0.5% decrease in the Earth's reflectance. Notably, Earth reflects around 30% of the sunlight that shines on it.

Philip Goode, a researcher at the New Jersey Institute of Technology and the lead author of the study said, "The albedo drop was such a surprise to us when we analysed the last three years of data after 17 years of nearly flat albedo."

Philip Goode was talking about the earthshine data from 1998 to 2017 which was collected by the Big Bear Solar Observatory in Southern California.

When this data was added to that of the previous years, researchers noted the dimming trend.

For the unversed, two things affect the net sunlight reaching the Earth: the Sun's brightness and the planet's reflectivity. However, the Earth's reflectance, at this time, was far from periodic changes in the Sun's brightness.

It was noted that there has been a change in the bright, reflective low-lying clouds over the eastern Pacific Ocean recently.

"It's actually quite concerning," said Edward Schwieterman, a planetary scientist at the University of California at Riverside.