this post was submitted on 18 Oct 2023
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Discussion of climate, how it is changing, activism around that, the politics, and the energy systems change we need in order to stabilize things.

As a starting point, the burning of fossil fuels, and to a lesser extent deforestation and release of methane are responsible for the warming in recent decades: Graph of temperature as observed with significant warming, and simulated without added greenhouse gases and other anthropogentic changes, which shows no significant warming

How much each change to the atmosphere has warmed the world: IPCC AR6 Figure 2 - Thee bar charts: first chart: how much each gas has warmed the world. About 1C of total warming. Second chart: about 1.5C of total warming from well-mixed greenhouse gases, offset by 0.4C of cooling from aerosols and negligible influence from changes to solar output, volcanoes, and internal variability. Third chart: about 1.25C of warming from CO2, 0.5C from methane, and a bunch more in small quantities from other gases. About 0.5C of cooling with large error bars from SO2.

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What will happen to the Greenland ice sheet if we miss our global warming targets (theconversation.com)
submitted 2 years ago by silence7@slrpnk.net to c/climate@slrpnk.net
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The results are fascinating. If temperatures peak at 2°C or so, and remain there, then the models – as expected – predict substantial ice sheet collapse after several thousands of years.

However, things change if warming is seriously mitigated post-2100. In those models, inertia in the ice sheet’s response – a bit like the time it takes for a ripple to settle down as it passes across a pond – means that an overshoot is at least partly reversible as long as temperatures are quickly brought back down.

The paper is here, and says:

Our results show that the maximum GMT and the time span of overshooting given GMT targets are critical in determining GrIS stability. We find a threshold GMT between 1.7 °C and 2.3 °C above preindustrial levels for an abrupt ice-sheet loss.

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[–] quicklime@lemm.ee 5 points 2 years ago (1 children)

There's no way we will stop in time for +2°C.

[–] silence7@slrpnk.net 7 points 2 years ago (1 children)

That's a human decision, and one that's not yet done. I'll be doing every bit I can for every tenth of a degree.

[–] LibertyLizard@slrpnk.net 2 points 2 years ago

God I love this comment. Well said.

[–] lntl@lemmy.ml 3 points 2 years ago

It'll melt.

[–] benjhm@sopuli.xyz 2 points 2 years ago

Seems like a key new paper, but not surprising to me. It takes a long time to melt ice kilometers thick, so it's the integral of warming that counts. However once its altitude drops below a certain level, the snow on the top becomes rain, and it can only go down.

threshold GMT between 1.7 °C and 2.3 °C

could be not far away now -and note also (abstract):

even temporarily overshooting the temperature threshold, without a transition to a new ice-sheet state, still leads to a peak in SLR of up to several metres