Earth Is Dimming – It’s Due to Climate Change
This image of Earth was compiled using tens of thousands of images from the Copernicus Sentinel-2 mission. Thanks to the satellite era, we are better placed to understand the complexities of our planet, particularly with respect to global change. Credit: Contains modified Copernicus Sentinel data (2019–20), processed by ESA and cloud layer from NASA
Warming oceans cause fewer bright clouds to reflect sunlight into space, admitting even more energy into earth’s climate system.
Warming ocean waters have caused a drop in the brightness of the Earth, according to a new study.
Researchers used decades of measurements of earthshine — the light reflected from Earth that illuminates the surface of the Moon — as well as satellite measurements to find that there has been a significant drop in Earth’s reflectance, or albedo, over the past two decades.
The Earth is now reflecting about half a watt less light per square meter than it was 20 years ago, with most of the drop occurring in the last three years of earthshine data, according to the new study in the AGU journal Geophysical Research Letters, which publishes high-impact, short-format reports with immediate implications spanning all Earth and space sciences.
That’s the equivalent of 0.5% decrease in the Earth’s reflectance. Earth reflects about 30% of the sunlight that shines on it.
Earthshine annual mean albedo 1998–2017 expressed as watts per square meter (W/m2). The CERES annual albedo 2001–2019 are 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 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 Earth Is Dimming – It’s Due to Climate Change