And now: A thread regarding my thoughts on "1.5°C"--not only as a Paris Agreement target, but also re: relevance to recent #climate events & overlaps (or not) w/geophysical realities. (This was originally written as a response to a journalist, who used excerpts in their article.)

First and foremost, it's absolutely true that every tenth of a degree matters; each increment of global warming will bring a relatively larger increase in adverse societal and ecological impacts than the last.

This statement is not so much about rate of warming itself, but a reflection of growing recognition that Earth system (especially the biosphere and cryosphere) can respond non-linearly, and sometimes abruptly or even irreversibly on human timescales, to gradual shifts in climate.

It's also a consequence of hydrological cycle intensification, which actually scales exponentially with warming--and, thus, we should *expect* to see an acceleration inintensity of events like flash floods, droughts, & wildfires so long as warming rate remains steady.

In this sense, each fraction of a degree of warming is (quite literally) worse than the last. That makes what we're facing over the next few decades seem quite daunting.

I have long been of the view, though, that the 1.5°C target was very unlikely to have been successful. It was a highly ambitious target even when it was first announced, given the climate and geopolitical trajectory of the time.