Please source your concerns from climate scientists, not professors of philosophy who say things like, '“There is a genuine possibility that within the coming century, we will hit temperatures that are deeply incompatible with the continued existence of human life,” he says.'

He's just plain wrong. Deemed an expert (by the article author) or no, MIT or no, that's just not what the research says, even if you add every highly improbable tipping-point effect together.

Read the IPCC AR6 WGII materials, for instance. The most wildly pessimistic predictions are very far from temperatures that are "deeply incompatible with the continued existence of human life". Setiya is claiming an existential threat. But climate scientists are not.

Climate change is an existential threat for low-lying island nations like the Maldives and Tuvalu. But it's not for humanity. "Setiya says that climate change remains an existential threat to a host of human cultures, traditions, and languages," the article says--yes, this is true, but this doesn't make it an existential threat overall.

Now you can use a nonstandard definition of existential--this is misleading but might be true in a sense. But it's better to let the experts define existential:

“The archetype of an existential risk is human extinction,” said Simon Beard, a researcher at the Center for the Study of Existential Risk at the University of Cambridge. “So literally all the humans dying.” (source: https://grist.org/climate/is-the-climate-crisis-an-existential-threat-scientists-weigh-in/)

'“I don’t think it’s an existential threat to humanity or ‘life on Earth,’” Daniel Swain, a climate scientist at the University of California, Los Angeles, told Grist. [...] “I do think climate change poses an existential threat to specific demographics of people and to specific species and ecosystems,” Swain said. “And that really should concern us greatly.”' (Emphasis mine.)

Note that Grist is not an idle observer here--their whole thing is to raise awareness of climate change and how it interacts with everything, with articles like "How climate change spurs megadroughts."

It's not just the climate scientists and (careful) climate advocacy groups saying this. FactCheck.org dinged Sanders specifically on his unqualified usage of "existential": https://www.factcheck.org/2019/10/factchecking-the-october-democratic-debate/.

We have lots of words to use to give an accurate perception of the dangers of climate change: serious, severe, catastrophic, calamitous, etc.; plenty of phrases too. But there are other words that go beyond what is appropriate to use for climate change unless used with qualification: existential (threat), annihilation, obliteration.

We needn't converse any longer--I've made my point plenty well enough by now, I think. Feel free to reply with the last word, which I will only correct if it contains an absolutely egregious falsehood that I think is also nonobvious enough that it might fool someone else who deserves to know better. Otherwise, I think the nature of the disagreement and the evidence for different positions is pretty plain by now.

Point is, climate change is extremely serious, but not existential (in the unqualified, conventional use of the term). Given the profusion of accurate terms to use, there is no reason to misuse "existential" to mean "really bad but not threatening existence", and given our predictions for changes, there is no reason to think it threatens existence overall.