Upper Atmosphere Cooling Rapidly; Stratosphere Lost 1% Of Its Depth (1,300 Feet) Since 1980
Ed. - Read the whole article if you can - this has the potential to open multiple cans of worms from space junk to sudden stratospheric warming to the return of ozone destruction.
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Satellite data have recently revealed that between 2002 and 2019, the mesosphere and lower thermosphere cooled by 3.1 degrees F (1.7 degrees C ). Mlynczak estimates that the doubling of CO2 levels thought likely by later this century will cause a cooling in these zones of around 13.5 degrees F (7.5 degrees C), which is between two and three times faster than the average warming expected at ground level.
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This month, he used new data on cooling in the middle and upper stratosphere to recalculate the strength of the statistical “signal” of the human fingerprint in climate change. He found that it was greatly strengthened, in particular because of the additional benefit provided by the lower level of background “noise” in the upper atmosphere from natural temperature variability. Santer found that the signal-to noise ratio for human influence grew fivefold, providing “incontrovertible evidence of human effects of the thermal structure of the Earth’s atmosphere.” We are “fundamentally changing” that thermal structure, he says. “These results make me very worried.”
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The depth of the stratosphere has diminished by about 1 percent, or 1,300 feet, since 1980, according to an analysis of NASA data by Petr Pisoft, an atmospheric physicist at Charles University in Prague. Above the stratosphere, Mlynczak found that the mesosphere and lower thermosphere contracted by almost 4,400 feet between 2002 and 2019. Part of this shrinking was due to a short-term decline in solar activity that has since ended, but 1,120 feet of it was due to cooling caused by the extra CO2, he calculates.
This contraction means the upper atmosphere is becoming less dense, which in turn reduces drag on satellites and other objects in low orbit — by around a third by 2070, calculates Ingrid Cnossen, a research fellow at the British Antarctic Survey. On the face of it, this is good news for satellite operators. Their payloads should stay operational for longer before falling back to Earth. But the problem is the other objects that share these altitudes. The growing amount of space junk — bits of equipment of various sorts left behind in orbit — are also sticking around longer, increasing the risk of collisions with currently operational satellites.
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https://e360.yale.edu/features/climate-change-upper-atmosphere-cooling