Earth dimming due to climate change

Warming oceans and fewer bright clouds

Earth’s reflectiveness is lowering with new reports suggesting that Earth is dimming because of climate change related issues including warming oceans and fewer bright clouds.

According to researchers climate change is increasing the temperatures of oceans and this in turn is causing reducing in bright clouds that reflect the sun light thereby resulting into Earth dimming and not being as reflective as before.

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.

Researchers claim based on their study that our planet 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. The study has been published in the AGU journal Geophysical Research Letters. That’s the equivalent of 0.5% decrease in the Earth’s reflectance. Earth reflects about 30% of the sunlight that shines on it.

Scientists explain that two things affect the net sunlight reaching the Earth: the Sun’s brightness and the planet’s reflectivity. The changes in Earth’s albedo observed by the researchers did not correlate with periodic changes in the Sun’s brightness, so that means changes in Earth’s reflectiveness are caused by something on the Earth.

Specifically, there has been a reduction of bright, reflective low-lying clouds over the eastern Pacific Ocean in the most recent years, according to satellite measurements made as part of NASA’s Clouds and the Earth’s Radiant Energy System (CERES) project.

That’s the same area, off the west coasts of North and South America, where increases in sea surface temperatures have been recorded because of the reversal of a climatic condition called the Pacific Decadal Oscillation, with likely connections to global climate change.

The dimming of the Earth can also be seen in terms of how much more solar energy is being captured by Earth’s climate system. Once this significant additional solar energy is in Earth’s atmosphere and oceans, it may contribute to global warming, as the extra sunlight is of the same magnitude as the total anthropogenic climate forcing over the last two decades.

“It’s actually quite concerning,” said Edward Schwieterman, a planetary scientist at the University of California at Riverside who was not involved in the new study. For some time, many scientists had hoped that a warmer Earth might lead to more clouds and higher albedo, which would then help to moderate warming and balance the climate system, he said. “But this shows the opposite is true.”

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