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Global Warming Felt By Space Junk and Satellites
An anonymous reader writes in with a story about another side effect of increased carbon dioxide in the atmosphere. "Rising carbon dioxide levels at the edge of space are apparently reducing the pull that Earth's atmosphere has on satellites and space junk, researchers say. The findings suggest that man made increases in carbon dioxide might be having effects on the Earth that are larger than expected, scientists added... in the highest reaches of the atmosphere, carbon dioxide can actually have a cooling effect. The main effects of carbon dioxide up there come from its collisions with oxygen atoms. These impacts excite carbon dioxide molecules, making them radiate heat. The density of carbon dioxide is too thin above altitudes of about 30 miles (50 kilometers) for the molecules to recapture this heat. Cooling the upper atmosphere causes it to contract, exerting less drag on satellites."
Because there's no extra heat coming in from the sun (indeed, slightly less), but because the CO2 is trapping heat in the lower atmosphere, the heat input to the upper atmosphere is reduced.
And what happens when heat input is reduced?
Cooling.
What happens in the lower atmoshere, where the heat input is increased?
Warming.
Indeed, one of the fingerprints that shows it ISN'T the sun doing it is the cooling upper atmosphere: in a warming sun, the entire atmosphere is being warmed because the heat input and throughput is increased.
Whereas the fingerprint of a greenhouse effect is that there is no extra input, but the throughput has changed.
In other words, this is yet more evidence of AGW.
HCFCs replaced CFCs because they don't react with ozone so don't destroy the ozone layer.
HCFCs do react with ozone and more so than CFCs. But since they're more reactive, they're more likely to decompose before they get to ozone-destroying altitudes.