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Humans have caused 1.5 °C of long-term global warming according to new estimates

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399 points gmays | 1 comments | 17 Nov 24 18:49 UTC | HN request time: 0.206s | source
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patrickhogan1 ◴[17 Nov 24 19:41 UTC] No.42166488[source]▶
Long-term should be defined. We can cool the planet the same amount long-term. Why is it taken as a given that any warming is irreversible when we have historical natural patterns showing global cooling (ice age)?
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1. mzhaase ◴[17 Nov 24 23:44 UTC] No.42168382[source]▶
There are changes that are irreversible in human time. For example the Greenland Glaciers were formed during an ice age but stable in pre industrial climate. Too much thawing would cause the entire tectonic plate to rise, raising the top of the glacier into a region of warm air that will melt it even if pre industrial temperatures are achieved again.

Greenland Glaciers have the surface area of Texas while being multiple kilometres thick. It alone is enough to cause sea-level rise of multiple metres. Also, melt water ingress into the Labrador sea might stop AMOC downwelling and could stop the gulf stream. All this would be irreversible during many human lifetimes.