Our planet has lost some of its lusters over the past twenty years. Scientists have noticed our world is getting dimmer as time goes on. Climate change may be responsible for this.
Researchers at the New Jersey Institute of Technology (NJIT) analyzed the amount of light reflected into space by the blue planet “earthshine” in a paper published in Geophysical Research Letters. Researchers found that the Earth is not as reflective as it used to be.
Using the Big Bear Solar Observatory in California, researchers measured the Earth’s albedo (the measure of solar radiation diffuse reflected) between 1998 and 2017. The data revealed that the Earth had dimmed by around half a percent since the early 2000s.
“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,” said Philip Goode, lead author of the paper and an astronomer at NJIT.
Earthshine annual mean albedo expressed as watts per square meter (W/m2). Credit: Goode et al. (2021), Geophysical Research Letters
Around 30 percent of all the sunlight that reaches our planet is reflected off the ocean, the clouds, and even the snow back into space. When the crescent moon is waxing, its dark side is visible due to this reflection.
There was no correlation between Earth’s dimming and the Sun’s brightness during the period of observation. It follows that the cause of the change must come from the Earth itself. Some researchers believe warming oceans are part of the cause.
NASA’s CERES project satellites revealed that a lack of low-lying clouds over certain parts of the Pacific could contribute to the Earth’s diminished brightness.