this post was submitted on 08 Dec 2023
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Climate - truthful information about climate, related activism and politics.

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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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[–] silence7@slrpnk.net 3 points 11 months ago (1 children)

Most of the exact boundaries for ecological tipping points aren't known with an 0.1ºC precision. I don't think we're going to get something like what you are asking for, just knowledge that each incremental increase in temperature is another step into a minefield.

[–] benjhm@sopuli.xyz 1 points 11 months ago (1 children)

True, but in principle we (i.e. big teams) could make impacts functions for each case and combine by integrating over risk (within which, value judgements also make a big difference - but that's something to learn too). To fit those functions we needed more studies by ESMs with smaller differences at the low end - if you don't study it, you won't know it (hence my point years ago - those models are slow, and big committee-run processes even worse).

[–] silence7@slrpnk.net 1 points 11 months ago (1 children)

Sure, it would be nice to know, but I don't see knowing as likely to change policy in any kind of meaningful way. That's going to take changing who holds power, not incremental knowledge.

[–] benjhm@sopuli.xyz 3 points 11 months ago* (last edited 11 months ago) (1 children)

I agree about that too - and think about how to model these power dynamics. Maybe you're suggesting (by this + posting the original) that we influence politics more by emphasising the crisis, regardless of the shape of that curve of increasing impacts. Such logic could also justify why they like to run high scenarios in ESMs. This doesn't convince people like me, but I know my way of thinking is not so typical, so maybe you are right.
Otoh there are some influential people, especially those who trust black boxes of economic optimisation models (there's another recent thread about that), for whom the lack of such info could effectively provide an excuse for delayed action.

[–] silence7@slrpnk.net 1 points 11 months ago

My impression is a lot of the high-emissions scenarios being used lets you demonstrate that there is an impact easily, even if the actual date of that impact looks to be somewhat later than under the most likely emissions scenarios.

And yes, the economic models are particularly awful; DICE has a bunch of assumptions in it about economic impact not affecting sectors which operate indoors and about damage being in the form of a fraction of GDP for that sector. eg: if agriculture is 3% of the economy by value, and it goes to zero, the overall impact is a 3% cut to economic output, even though no food means no economy.