- Researchers use decades of measurements of soil and clouds
- Earthshine is the light reflected from Earth to illuminate the surface of the Moon.
- This allows the team to see how much solar radiation is reflected off Earth.
- He found a marked drop in the Earth’s reflected light in his measurements.
- This means more solar radiation is penetrating the Earth and can warm the air.
A new study warns that Earth is shrinking because warmer oceans are causing less luminous clouds to reflect sunlight into space, trapping more energy in our planet.
Decades of measurements of Earth’s brightness – the light reflected from Earth that illuminates the surface of the Moon – allowed the team at the New Jersey Institute of Technology to get a better picture of the effects of climate change.
They also used satellite measurements to find that ‘a significant drop in Earth’s reflectivity’, or albedo, has occurred over the past two decades.
According to researchers, Earth is now reflecting about half a watt less light per square meter than it was 20 years ago.
The team said that half the drop in light occurred over the past three years, after 17 years of flat albedo, mainly due to low clouds over the Pacific Ocean.
Scientists had hoped that a warmer Earth caused by climate change would create more clouds, and a higher albedo to reduce warming, but the opposite appears to be happening, which could accelerate climate change. Is.
A study warns that Earth is shrinking because warmer oceans are causing less luminous clouds to reflect sunlight into space, trapping more energy in our planet.
Decades of measurement of Earth’s luminosity (the blue dot) – the light reflected from Earth that illuminates the Moon’s surface – allowed the New Jersey Institute of Technology team to get a better picture of the effects of climate change
What is Albedo?
Albedo is a measure of the reflectance of solar radiation from Earth.
It is taken on a scale of zero to one, where one is white and zero is black.
A black body absorbs all incident radiation, and this includes things like water, crops, and forests.
At the other end of the scale, a white body reflects solar radiation into space, including snow and clouds.
Albedo is important in climatology, astronomy and environmental management.
Earth’s average albedo is 30 to 35 percent, which fluctuates depending on the level of the Sun’s activity.
It can also vary widely at the local level depending on the cloud cover.
Climate change is causing some atmospheric changes, reducing cloud cover in some areas and reducing albedo.
This means that more of the Sun’s energy is penetrating the Earth and as a result the oceans can warm and exceed the higher average global temperature.
If it does, it will act faster and make climate change worse.
The team found that Earth’s reflectivity had decreased by about 0.5 percent over the past three years—which now reflects 29.5 percent of all sunlight.
“The albedo drop was a surprise to us when we analyzed the data for the past three years after 17 years of nearly flat albedo,” said lead author Philippe Goode.
He was referring to Earthshine data from 1998 to 2017 gathered by the Big Bear Solar Observatory in Southern California.
When the latest data was added in previous years, the dimming trend became apparent to the team.
Two things affect the net sunlight reaching Earth: the Sun’s luminosity and the planet’s reflectivity.
The changes in Earth’s albedo observed by the researchers were not related to periodic changes in the Sun’s brightness, meaning that changes in Earth’s reflectivity are caused by something on Earth.
When other observations looked for obvious changes that could result in this change in albedo, the team turned to NASA satellites.
Satellite measurements carried out as part of NASA’s Clouds and Earth’s Radiant Energy System (CERES) project revealed a lack of bright, reflective low-lying clouds over the eastern Pacific Ocean in recent years.
This is the same area, off the western coasts of North and South America, where sea surface temperatures have increased.
This increase is due to a reversal of a climate condition called the Pacific Decadal Oscillation, with a possible connection to global climate change.
Earth’s turbidity can also be seen in terms of how much solar energy is being captured by Earth’s climate system.
He said that once this significant additional solar energy gets into Earth’s atmosphere and oceans, it could contribute to global warming, as the excess sunlight in the form of total human-caused climate change over the past two decades. The magnitude is the same.
This matches the findings of a NASA study published in June, which found that Earth’s energy imbalance had doubled from 2005 to 2019.
This means more energy is being absorbed from the Sun than is reflected back into space, throwing Earth’s energy ‘out of balance’ and heating the planet.
Researchers say that the Earth’s positive energy imbalance is due to increasing atmospheric pollution in the form of greenhouse gases such as carbon dioxide (CO2), methane (CH4) and ozone (O3).
The team said half the drop in light occurred over the past three years, after 17 years of flat albedo – mainly due to low clouds over the Pacific Ocean.
These pollutants block the Earth’s heat from being released into space, increase the absorption of sunlight and trap heat within the atmosphere.
Until the rate of warming slows down, more changes in the climate should be expected than are already happening, experts have warned.
“It’s actually quite worrying,” said Edward Schwetterman, 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 have more clouds and higher albedo, which then…