Scientists find that Climate Change is causing Earth to lose its shine

The far reach effects that climate change has on our planet is something researchers are still uncovering. The crisis is responsible for large swaths of problems our planet is currently experiencing, including loss of sea ice, accelerated sea-level rise, and longer, more intense heat waves. Now, a new study indicates that climate change has caused Earth to dim — literally!

According to the study, our planet’s brightness has decreased and the culprit may be warming oceans.

Researchers used decades of measurements of ‘earthshine’, which is light reflected from Earth onto the surface of the Moon, as well as satellite observations to find that there has been a significant decrease in Earth’s reflection or ‘albedo’, since 1998.

“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,” said Philip Goode, a researcher at New Jersey Institute of Technology and the lead author of the new study, referring to gathered earthshine data.

Earthshine is seen on the darker unlit side of the Moon. The Portion studied by researchers.
Image from NASA captured onboard the ISS. Edited by the Space Explored team

Researchers, including Goode, used albedo data collected at the Big Bear Solar Observatory in California between 1998 and 2017 to calculate an earthshine trend line.

Their research found that our home planet now reflects about half a watt less light per square meter than it did 20 years ago, with the most significant drop being just in the last 3 years, according to the new study published. This equates to an overall reduction of 0.5% in Earth reflectance. Earth reflects about 30% of the sunlight that shines on it.

Earthshine annual mean between 1998–2017 expressed as watts per square meter (W/m2). The CERES annual albedo 2001–2019 is shown in blue. A best-fit line to the CERES data (2001–2019) is shown with a blue dashed line. Average error bars for CERES measurements are of the order of 0.2 W/m2. Credit: Goode et al. (2021), Geophysical Research Letters

The team compared their findings with those of NASA’s Clouds and the Earth’s Radiant Energy System (CERES) project, which features five satellites measuring reflectiveness, and found the reduction in low-lying clouds over the eastern Pacific may have resulted in the albedo drop off. This supports a hypothesis researchers feared. That an increase in ocean surface temperatures is causing a reduction in cloud cover, which has “likely connections” to the climate crisis.

“It’s actually quite concerning,” said Edward Schwieterman, a planetary scientist at the University of California at Riverside who was not involved in the study. For years, climate scientists were hopeful that a warmer planet would lead to more clouds and higher albedo, which would substantially help to reduce the warming of our planet and balance the climate system, he said. “But this shows the opposite is true.”

When oceans are warmer, weaker atmospheric circulation occurs, and these reflective, bright, low-level clouds that are responsible for reflecting light seem to dissipate. This means that more sunlight is being absorbed by Earth and less is being reflected, making our ‘Pale Blue Dot’ dimmer. But with more light (aka solar radiation) hitting our planet’s surface, comes more heat trapped in our atmosphere. The consequences of which open the doors to a dangerous runaway greenhouse effect.

The team noted in their conclusions that their analysis of earthshine can be prone to a lack of sensitivity because of long-term calibration issues and strongly encourage further observations before coming to a complete conclusion.

The AGU study published on Wednesday can be accessed here.

Featured image credit: ESA/Alexander Gerst

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