According to one study, the Earth has lost some of its brightness over time. The researchers believe that it is because there are fewer clouds that return the light.
Earth returns less light to space because its cloud cover is no longer what it used to be, according to one study.
According to the researchers, this is because cloud cover has been reduced by a fluctuation in ocean temperatures.
Philip Goode, a researcher at the New Jersey Institute of Technology (USA) and lead author of the study, has shared his findings with CNN.
“Off the western coast of America, the low-lying clouds burned up and more sunlight came in, so we saw that Earth’s reflectance had decreased,” he explains.
The study has analyzed a phenomenon called “earthly glow“. In the same way that the moon returns light from the sun, giving it that silvery-gray look in the night sky, the Earth reflects about 30% of the sunlight it receives, making it look like a blue marble from space.
Scientists are able to measure the reflection of the Earth on the dark side of the Moon, which is called terrestrial brightness.
The brightness of the Earth on the Moon has been more or less constant in the last 17 years. “We were a little reluctant to do the data for the last 3 years because it looked the same,” Goode tells CNN.
However, when Goode and his colleagues looked, “the reflectance had dropped significantly,” he shared in a statement to the outlet.
So much so that scientists at the Big Bear Solar Observatory in California, which has been monitoring the Earth’s brightness since the mid-1990s, thought they were wrong.
“We did it several times and it turned out to be correct,” confirms Goode.
Scientists have found that the Earth’s ability to reflect sunlight – a measurable trait called “albedo” – has decreased by 0.5 watts per square meter.
This means that Earth is receiving 0.5% more sunlight compared to levels in the first decade of 2000, as reported by CNN, what is “climatologically significant”say the scientists in the study.
[El albedo anual de CERES 2001-2019, también expresado en W/m2, se muestra en azul. Una línea de mejor ajuste a los datos de CERES (2001-2019) se muestra con una línea discontinua azul. Las barras de error medias de las mediciones de CERES son del orden de 0,2 W/m2]
The results were published in the journal Geophysical Research Letters on August 29.
Scientists attribute the loss of albedo to fewer clouds in the atmosphere that return light to space.
Specifically, they attribute the change to the Pacific Decadal Oscillation, a long-term fluctuation in the Pacific Ocean during which the ocean warms or cools, influencing the jet stream and weather patterns, according to NASA.
A 2016 study found that climate change it is also changing the cloud cover, shifting it towards the poles, which is affecting the albedo of the Earth, as previously reported by Business Insider.
However, scientists have not mentioned climate change in the 2021 study.
Speaking to CNN, Goode has not wanted to venture how the loss of albedo could affect the planet.
But Edward Schwieterman, a planetary scientist at the University of California at Riverside (USA) who was not involved in the study, said in a statement that is “really quite disturbing”.
Scientists expected that global warming would cause more clouds in the atmosphere, which could counteract some of the warming by reflecting more sunlight.
“But this shows otherwise,” he says.
This article was published in Business Insider Spain by Carlos Galán Feced.