NASA satellites have found that an important layer of the Earth’s atmosphere — the mesosphere, a 50-100 km high atmospheric layer that protects us from 40,000 tons of meteors each year –is cooling and contracting by 500 to 650 feet each decade. Using data from three NASA satellites, scientists were able to produce a long-term record from 30 years of observation. Upon analysing the data, scientists found that the mesosphere is cooling down by up to 2.7 degrees Celsius per decade.
According to scientists, a contracting mesosphere will shrink the upper atmosphere with it, reducing satellite drag. Satellite drag is friction in the upper atmosphere that pushes satellites out of orbits. Reduced satellite drag would mean more space junk in the upper atmosphere.
The shrinking mesosphere is caused by greenhouse gas emissions and the new findings do not surprise the scientists as they were expecting such an effect of the emissions. “It would have been weirder if our analysis of the data didn’t show this,” said Brentha Thurairajah, one of the authors of the study, in a NASA news release. The study was published on April 20 in the Journal of Atmospheric and Solar-Terrestrial Physics.
According to scientists, Greenhouse gases trap most heat in the troposphere — the lowest layer of the atmosphere — itself and re-emit to Earth. This effect causes the Earth’s surface, sea surface and troposphere to heat up, causing global warming. However, another effect of this is that less heat reaches the mesosphere, and whatever heat touches sparse carbon dioxide molecules in this thin layeris re-emitted to space. This is why, the cooling down of the mesosphere is directly linked with greenhouse gas emissions.
In another recent discovery, environmental scientists had found that the stratosphere, the layer of the atmosphere below the mesosphere, has been shrinking by over 300 feet per decade. Greenhouse gases are the main cause behind the shrinkage of this another crucial layer of our atmosphere. The shrinkage in the stratosphere can cause disturbance in radio communication and global positioning systems.
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