The warming of the waters of the World Ocean has led to a decrease in the brightness of the Earth.

Scientists are concerned about an unexpected fact: the warming of the waters of the World Ocean has led to a decrease in the brightness of the Earth.

Experts have studied measurements of the Earth’s radiance – the light reflected from our planet, which illuminates the surface of the Moon – as well as various data from satellites and learned something strange, writes Phys.org.

The earth now reflects about half a watt less light per square meter than it did 20 years ago. This is equivalent to a 0.5% decrease in the planet’s reflectivity. Moreover, most of the decline has occurred in the last three years. In general, the Earth now reflects about 30% of the incident sunlight.

“The fall in albedo was a huge surprise for us! We analyzed data from the last three years after 17 years of almost constant albedo, ”said Philip Goode, a scientist at the New Jersey Institute of Technology and lead author of the new study. The Earth’s “dimming” trend became apparent after experts added new data to the Earth’s radiance measurements from 1998 to 2017, collected by the Big Bear Solar Observatory in Southern California.


Average annual albedo of the Earth’s radiance 1998–2017. expressed in watts per square meter (W / m2) and shown in black. Results 2001–2019 shown in blue. The average measurement error is about 0.2 W / m2. Photo: Goode et al. (2021), Geophysical Research Letters

Pure sunlight reaching the Earth is influenced by two things: the brightness of the Sun and the reflectivity of the planet. The changes in the Earth’s albedo observed by the researchers did not correlate with periodic changes in the brightness of the Sun. This means that changes in the reflectivity of the Earth are caused by something on our planet, and not from the outside.


See how the Earth twinkles with its lights in this photo from space. Source: ESA / NASA

In particular, satellite measurements from NASA’s Clouds and Earth Radiant Energy System (CERES) project have shown a reduction in bright reflective low-lying clouds over the eastern Pacific in recent years. This area is located off the western coast of the Americas. Previously, there was also an increase in water surface temperature due to a change in climatic conditions, called the Pacific Decadal Oscillation. It, in turn, is associated with the problem of global warming.

Darkening of the Earth can also be viewed in terms of how much more solar energy is captured by the Earth’s climate system. When this significant additional solar energy enters the Earth’s atmosphere and oceans, it can contribute to global warming, since the additional sunlight has the same magnitude as the total anthropogenic impact on climate over the past two decades.

“It’s actually quite disturbing,” says Edward Schwieterman, a planetary scientist at the University of California, Riverside. Previously, many scientists had hoped that a warmer Earth could lead to more clouds and higher albedo, which would then help mitigate warming and balance the climate system. But, judging by the data of experts, the opposite process is taking place.

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