Right, I'm on holiday, so was spending time w/ family, and didn't have time to go through the 4? 5? whatever reasons this statement is wrongety-wrong-wrong-wrong. So that's a bit unfair, but the world isn't fair. Twitter isn't fair. I'm probably not fair. 2/

I'm going to make up for it by explaining all 4? 5? separate reasons the quoted statement is wrong. Let's go. Reason #1: a global mean temp differential, by itself, says nothing about safety. It's the values it covers which makes it unsafe. Warming changes these values. 3/

Reason #2: the mean temperature value itself is not the main source of danger. It's the variability around the mean which brings that temperature mean into deadly territory. So a "safe" mean value leads to mass death via the distribution. Graph from 4/
https://twitter.com/robhon_/status/1312429132668522496

This is not a hypothetical shift. These deaths from increasing heat waves are already being observed, with countries like India hit hardest. So it's super disingenuous to say that "human physiology can cope". It's literally dancing on ppl's graves. 5/ https://indianexpress.com/article/lifestyle/health/heat-related-deaths-among-elderly-lancet-countdown-report-7080744/

Reason #3: Temperature is amplified by humidity via the wet-bulb effect. The human metabolism cannot survive any amount of time beyond certain temperature humidity conditions. Figure from Mora et al 2018. Entire parts of the planet become uninhabitable. 6/
http://www.natureasia.com/en/research/highlight/11960

Reason #4: Temperature is only one limited category of climate impacts. Saying climate change is safe because temperature differences are manageable is like saying going through a wood chipper is safe because you're used to filing your nails. Does not compute. 7/

We're talking droughts, floods, crop failures, tornado fires that make their own weather, mega-storms repeatedly pummelling areas that had never experienced storms before (like Mozambique), sea level rise devastating Bangladesh & other low lying areas 8/ https://twitter.com/MikeHudema/status/1213076165348470784

disease and parasite spread, crushing biodiversity loss, ocean acidification AND warming and on and on. And it's happening now. Everyone please follow @ri_montu for reports and photographs from Bangladesh. Don't look away. 9/ https://twitter.com/ri_montu/status/1340857710460301312

Where was I? Oh yes, reason #5. It's not just temperature averages. It's not just temperature ranges. It's not just the whole gamut of biblical disasters that global warming brings with it. It's the systemic impacts that climate change enacts via ecosystems. 10/

You seriously want to say we'll survive 3°C warming because 3 is a small number on your thermostat? Then surely you can write a rebuttal to this article showing that close to half of all plant & insect species, as well as 1/4 of vertebrates, are at risk of extinction at 3°C. 11/

Link to article here . Newsflash: we depend on other species and ecosystems to live. We depend on plants & insects especially. A few of us might be able to ride out this kind of mass extinction, but it's hard to see how many billion of us could. 12/ https://science.sciencemag.org/content/360/6390/791/tab-article-info

It's certainly not the kind of irreversible cataclysm you'd want to send humanity through because "4°C is a small number" ffs. And reason #6, because all of our socio-economic systems and infrastructure depend on stability, including climatic stability. 13/

No one serious believes that the economic, political and military crises that will accompany the climate crisis will be harmless, or are harmless already. 14/

For all this talk about "humans can cope and adapt", the best and safest way out of this is to reduce emissions immediately, and very fast. Anyone saying otherwise is a dangerous fool, and I will call them that. Damsel out. End.

Mic drop slightly marred by the fact that this thread was supposed to start with this tweet, but I failed basic twitter threading, so there ya go. This is what started it all ... https://twitter.com/JKSteinberger/status/1344264877397975040