Research conducted over the last two decades has revealed that Earth is losing its shine, which is not good news, and — as usual — it’s probably our fault. Why? Because the planet has most likely lost its lustre due to climate change, and could even exacerbate the effects of future global warming.

The study, first published in the journal Geophysical Research Letters, involved tracking the planet’s glow between 1998 and 2017, incorporating around 1,500 nights’ worth of data gathered at Southern California’s Big Bear Solar Observatory. 

This was partly achieved by observing a phenomenon named “earthshine”, the light that Earth reflects on the dark side of the moon, giving it a pale glow against the darker night sky. These “earthshine” measurements were combined with data about the brightness of the sun, and satellite analysis of Earth’s reflectivity (or albedo) from NASA’s Clouds and the Earth’s Radiant Energy System (CERES) project.

The resulting discovery was that Earth’s brightness has dimmed by about half a per cent since the 90s. Most of the drop occurs in the final three years leading up to 2017 (where the analysis ended), and is followed by an even steeper decline over 2018 and 2019.

0.5 per cent may not sound like a lot, but Philip Goode, a New Jersey Institute of Technology astronomer and lead author of the study, says: “The albedo drop was such a surprise to us when we analyzed the last three years of data after 17 years of nearly flat albedo.”

The research team concluded that changes in the sun’s brightness didn’t correlate with the dimming of Earth, meaning that something on the planet itself must have changed. That something could be a reduction in low-lying clouds over the eastern Pacific, where sea surface temperatures have sharply increased, with “likely connections” to the climate crisis.

“It’s actually quite concerning,” adds Edward Schwieterman, a planetary scientist at the University of California at Riverside. While scientists previously predicted that a warmer planet could lead to more clouds — meaning more of the sun’s heat would be reflected and less trapped by greenhouse gases — “this shows the opposite is true”. 

Basically, the (literally) dark conclusion is that the dimming of Earth could actually make the effects of global warming occur at an even faster rate, with implications for the future of Earth’s climate.