[esarbe]

You might be underestimating the social upheaval that will result from wast regions of the earth becoming uninhabitable and the effect of the population movements from desperate people trying to get away starvation.

You might also be underestimating the consequences of ecosystem collapse. Since 1970 we've already lost about 60% of biomass of insects, birds and mammals. The impact of rapid climate change will put additional pressure on already vulnerable species.

I have little doubt that widespread ecosystem collapse will be the death nail for our global human civilization.

[RandomLensman]

So you are an expert in these things that you don't trust other experts? Catastrophic collapse is not really something generally assumed on the 2-3 degree warming path.

[gameoverhumans]

> So you are an expert in these things that you don't trust other experts

I don't see how the grandparent comment implied a lack of trust in other experts, nor did they imply themselves to be experts.

> Catastrophic collapse is not really something generally assumed on the 2-3 degree warming path.

Actually, the IPCC, which tends to be rather optimistic on how bad things could be (or already are), predicts pretty significant socioeconomic problems arising from 2-3 degrees warming: https://en.wikipedia.org/wiki/Shared_Socioeconomic_Pathways

It doesn't take much imagination to come up with ways that "Social cohesion degrades and conflict and unrest become increasingly common" leads to "nation states with nukes and experiencing extreme scarcity and high social unrest declare war on each other"...

[RandomLensman]

Your imagination might not be a good guide to take you from degrading social cohesion to something like nuclear war.

Even in general, socio-economic models are not of the same quality as the physics models (and no-one is making that claim anyway). The SSPs are more like share narratives rather than forecasts.

[gameoverhumans]

Okay so we've established that neither my imagination, nor the labors of the Intergovernmental Panel on Climate Change are any good for determining how likely we are on course for nuclear war.

You know that humans do have nukes, right? And a long history of killing each other over pretty much anything? (from land rights to idealogies and everything in between).

So in your estimation, who would be a good source to determine how/whether humans get to a point where nuclear war is a likely scenario?

[RandomLensman]

I explained to you what the SSPs are.

Why the obsession with nuclear war and trying to get totally imprecise scenarios there? They serve very little purpose other than building scary narratives. Some people's job is to worry about them, but that doesn't mean they are central to what we should do.

When a hurricane strikes, things are usually not just Lord Of The Flies - the idea of collapse into violent chaos is a popular one but doesn't really happen much.

[esarbe]

I'm not sure what you are talking about re "experts" - I'm very much basing my statements on the conclusion drawn by experts.

I don't think that there's any expert out there that will deny that 3°C warming will lead to massive population movements.[0] Experts also conclude that there's already significant damage to ecosystems that will only increase with that kind of global warming[1].

But that's a little besides the point.

In the Paris climate agreement of 2015 we agreed to limit global warming to 1.5°C. Barely 8 years later we've blown through that limit and there is no credible effort to reduce or even stop the warming.

Models parametrized so that they predict a 2-3°C increase until the end of the century have already been invalidated since all of them expected 1.5°C to be breached by 2030 earliest - we're seven years ahead of schedule.

Right now we're on a track that even our modern neutered climate models predict will lead to a +5°C before the end of the century.

[0] https://www.ipcc.ch/report/sixth-assessment-report-working-g...

[1] https://www.nature.com/articles/s41586-020-2189-9

[RandomLensman]

1.5C is gone - no point clinging to it. However, there is a lot if effort going into decarbonization. Where we are exactly is unclear, but claiming we are on track to 5C isn't really supported by that many (having past models being invalidated doesn't mean certain future overshoot, how much of invested changes are captured, etc.).

Also, the ecosystem discussion is somewhat orthogonal as we don't now what all is critical to human survival.

[esarbe]

> 1.5C is gone - no point clinging to it.

And soon 2.0C will be gone - no point clinging to it, right?

> However, there is a lot if effort going into decarbonization.

I don't see a lot of effort going into decarbonization. We still have about 7% of global GDP going into subsidies for fossil fuels. That's a lot of effort against decarbonization [0].

There is little actual progress being made[1]. Whatever reduction we had can be directly attributed to the economic upheaval created by the Covid pandemic.

> having past models being invalidated doesn't mean certain future overshoot

Given that our actions in the last 20 years pretty much track the "business as usual" scenario and given that we can eliminate all models that predict a warming of 1.5°C to arise any later than 2024, we're pretty much only left with models that give us a warming of 5°C until 2100[2]. Please note that even that is in the lower bound; the IPC 8.5 has a lower bound of 1.4°C in the 2040 - we've blown past that already. It's only getting worse.

> Also, the ecosystem discussion is somewhat orthogonal as we don't now what all is critical to human survival.

I'm not sure if you are joking or what. Our dependency on an intact ecosystem is absolute - we cannot exist without it. The "services" that the biosystems around us provide is invaluable and we utterly depend on them. Trying to quantify how much of it you can destroy for the sake of industry and profit is akin to asking how much of your liver you can sell away for cocaine.

[0] https://www.imf.org/en/Topics/climate-change/energy-subsidie...

[1] https://ourworldindata.org/co2-emissions

[2] https://en.wikipedia.org/wiki/Representative_Concentration_P...