work published in scientific journal Geophysical Research Papers There are suggestions that global warming is contributing to the darkening of the blue planet.
Earth is not as bright as it used to be and is getting dark in recent years, researchers say in a study in the journal Geophysical Research Papers and reported by CNN.
Working at the Big Bear Lake Solar Observatory in California, which specializes in studying the Sun, astronomers have compiled data every night for the past twenty years to study the solar cycle and cloud cover.
half watt low light per square meter
They obtained these results by measuring Earth’s light, which occurs when the dark side of the Moon captures the reflected light from Earth and reflects it back. The magnitude of the illumination varies according to the night and the season of the year.
“When you look at a quarter of the Moon, you can see it all because three quarters are illuminated by that ghostly light,” says Philip Goode, a researcher at the New Jersey Institute of Technology and lead new study author.
After twenty years of measuring the ghostly light, the researchers found that it was fading. “It’s actually sunlight that reflects off Earth, and that’s what causes darkness,” continues Philippe Goode.
Earth now reflects half a watt less light per square meter than it did twenty years ago. This represents a 0.5% reduction in reflectance, or the proportion of light reflected from Earth, during this period. A significant drop as Earth reflects about 30% of the light coming from the Sun.
A remarkable darkening in the last three years
During the first 17 years, the data collected at the American observatory was relatively uniform. It wasn’t until three years ago that researchers noticed that Earth’s brightness had dropped significantly that they thought their conclusions were flawed.
“The reflection was significantly reduced, we thought we had done something wrong,” explains Philipp Goode, “then it turns out the data was correct.”
Clouds less bright due to global warming
Unable to establish a connection between their data and the Sun’s changing brightness due to its solar cycles, the researchers looked at another factor: cloud cover. They saw a decrease in it due to climate change. Since sunlight bounces off the clouds less, it is less likely to be reflected back into space. Therefore the blue planet is less bright.
This reduction in cloud cover, especially observed along the western coasts of North and South America, results from the absorption of light radiation from the Sun by the ocean and therefore the Earth’s surface, thereby increasing its temperature. In other words, global warming only leads to more global warming.
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