Thread by @ClimateBen

'The last time global surface temperature was sustained at or above 2.5°C was over 3 million years ago' in the Pliocene, with CO2 levels like today.

We could reach 2.5°C by 2100 if emissions 'stay close to today's levels over a few more decades'.

May that even risk 3°C-4°C?

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Scientists tell me not to expect 4C by the 2060s (see 2009 article), but they appear to be clear 3.5C-4C by 2081-2100 is entirely plausible.

If emissions don't drop by the 2040s, could we face up to unthinkable 3.5C-4C,not just horrific 2.5C?

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theguardian.com/environment/20…

The best estimates (and very likely ranges) for 2081-2100 in the two scenarios that I believe are widely considered to correspond to our current situation are 2.7C (2.1-3.5C) and 3.6C (2.8-4.6C).

Could another 15-25 years of emissions around today's levels mean 3-4C by 2090?

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1.5C-2.5C is already catastrophic enough to leave 100,000s or millions of species struggling, including humans in my opinion.

I ask whether and under what conditions 3-4C by 2090 would be plausible in light if this conversation from yesterday:



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'We have already observed impacts of climate change on agriculture. We have assessed the amount of climate change we can adapt to. There’s a lot we can’t adapt to even at 2C. At 4C the impacts are very high and we cannot adapt to them'

2C by 2038-2052?

5/theconversation.com/ipcc-expert-wr…

This excellent IPCC AR6 WG1 thread by @valmasdel is extremely helpful. Clear, concise, fascinating, and terrifying.

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How many people have grasped this?

⬇️



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Have media and education systems made the ideas in this thread clear to us all? I think not.

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There's every reason to think we can't avoid 2.3-2.8C.

Can this be delayed for many centuries or beyond (which may help species to adapt) or will it hit by 2050-2150 which would be too fast for species to cope?

Most scientists expect 2.3-2.8C by 2100.

9/cbc.ca/news/science/c…

We could still hit 4C-5C. What survives that? See here:



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