Warmer oceans seem to be generating fewer bright clouds, in turn less sunlight is reflected back into space – a feedback.

Measurements of data spanning two decades, of the reflectance or albedo of Earth based on the earthshine that illuminates the Moon show that Earth is now reflecting about half a watt less light per square meter compared to 1998, a decrease of a 0.5 percent in Earth’s reflectance. In total, our planet reflects about 30 percent of the sunlight that reaches it.

Science Alert: The brightness of Earth depends on both the amount of sunlight reaching it and the reflectiveness of the planet. This study showed the two factors were not in tandem, so something on Earth is causing the dimming, especially in recent years.

Satellite measurements looked at by the research team suggest that a reduction in bright, reflective, low-lying clouds over the eastern Pacific Ocean has been a major contributor to the reduction in Earth’s brightness shown in the data.

And it’s all likely to be connected to climate change. In the same areas where bright clouds are thinning, ocean surface temperatures are rising, possibly caused by the reversal of a climatic condition called the Pacific Decadal Oscillation.

“[Earth’s albedo] is an essential determinant of the earth’s climate, since, in the broadest sense, changes in climate arise from the simultaneous evolution of the solar intensity, the Earth’s albedo, and greenhouse insulation,” write the researchers in their published paper.

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“Stringent data quality standards were applied to generate monthly and annual means,” conclude the researchers. “These vary significantly on monthly, annual, and decadal scales with the net being a gradual decline over the two decades, which accelerated in the most recent years.”

Related

• • The Dimming of Planet Earth
  • Teaser image via Pixabay.