this post was submitted on 01 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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[–] [email protected] 7 points 1 year ago (2 children)

Already there. Average has been above 1.5°C since August.

[–] [email protected] 3 points 1 year ago* (last edited 1 year ago)

Warming surpassed the 1.5-degree mark for one month or more in 2016, 2017, 2019, 2020, and again in 2023.
Measured across the entire year, 2023 will conclude 1.4 degrees hotter than the preindustrial era, and at least one of the next five years is expected to surpass 1.5 degrees. But it’s unclear at what point the world will have officially breached the Paris target, as the pact offers no clear guidance on this matter.

By Copernicus's metric, we're currently at about 1.25C long-term average and on track to pass 1.5C in about a decade.

[–] [email protected] 2 points 1 year ago

All a bit surreal, because it really isn't a physical threshold - just a diplomatic one, lower than 2ºC (too high to save some islands, deltas, food, ecosystems), and higher than 1ºC (already passed when they wanted a lower target). There was originally some paleoclimatic justification for 2ºC, but not with any precision, these round numbers depend on our definition of degrees as 1% of the range from freezing to boiling water.
Sure the physical climate system includes many tipping points, but their thresholds vary by region and sector and we don't know them with precision. So when you try to integrate risk across projected impacts (result of which depends strongly on value judgements) you get a curve, on which nobody has shown that 1.5 marks a special nonlinearity.
Diplomatic thresholds do matter for our social system, but we should acknowledge these for what they are.
Otherwise it tempts the reaction - ok we failed, world's going to end, let's go have another [conference of the] party.