Global Warming

Earth is Dimming due to Climate Change

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.

Specifically, there has been a reduction of bright, reflective low-lying clouds over the eastern Pacific Ocean in the most recent years. 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.

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.

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