s countries prepare to meet in the coming months to accelerate action towards the goals of the Paris Agreement, the situation is getting alarming with every passing day. Scientists have now found that parts of the upper atmosphere are gradually contracting.
The culprit being greenhouse gas emissions and the growing menace of climate change.
In a study published in the journal Science Direct, scientists said that the mesosphere, a layer of the atmosphere that extends 50 to 80 kilometres above the surface, is cooling and contracting. While scientists have long predicted the effects of greenhouse emissions, it is the first time that such trends have been observed over a period of time.
Scientists combined data from three NASA satellites and produced a long-term record of developments spanning over 30 years indicating that the summer mesosphere over Earth’s poles is cooling by four to five degrees Fahrenheit and contracting at a rate of 500 to 650 feet per decade.
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The lead author of the study, Scott Bailey, an atmospheric scientist at Virginia Tech, said, “You need several decades to get a handle on these trends and isolate what’s happening due to greenhouse gas emissions, solar cycle changes, and other effects.”
A major cause of concern is the growing threat to satellites as atmospheric gases cause satellite drag, the friction that tugs satellites out of orbit and helps clear space junk. As the mesosphere contracts, the rest of the upper atmosphere above sinks with it, which can lead to a decline in the drag and increase in space junk.
Why is the mesosphere important?
The mesosphere lies just above the stratosphere, which has the critical ozone layer that protects us from the deadly ultraviolet radiation of the Sun. Studying the mesosphere, therefore, becomes important as it is responsible for changes in atmospheric composition and could provide scientists with clues about how additional greenhouse emissions could change in temperature and water composition of the atmosphere.
The upper boundary of the mesosphere, about 50 miles above Earth, is where the coolest atmospheric temperatures are found. Characterised by their brilliant icy clouds huddled around the North and South Poles, changes in the mesosphere could affect the poles. Scientists have observed an odd change in these clouds as they get brighter, drift farther from the poles, and are appearing earlier than usual.
“The only way you would expect them to change this way is if the temperature is getting colder and water vapour is increasing,” Russell said. Colder temperatures and abundant water vapour are both linked with climate change in the upper atmosphere.