Emily Cunningham

But 2C isn't a "likely" scenario—it's a tremendously optimistic scenario. Today we are on track for more than 4C by the end of the century—after which, warming could continue.

Over the last 30 years, the world as a whole has done little to nothing to bend those curves downward. In fact, last year we added carbon to the atmosphere at an unprecedented rate. Every year is worse than the last.

The upper-end of the UN's bell curve of possibilities puts the planet at 8C warmer by the end of the century—a worst-case outcome of a do-nothing carbon trajectory.

4C may seem unthinkable, with such horrifying impacts we would like to believe the chances are vanishingly slim we get there. But while I think we will avoid that amount of warming, it is far from a worst case.

That we often think of it that way is a reflection of just how tilted toward best-case and even beyond-bast-case most scientific research has been over the last few decades, when we did little in response.

Which is why, at this point, unfortunately, our likeliest outcomes are actually quite catastrophic, and catastrophic outcomes actually quite likely. (x/x)

David, I agree with just about everything you wrote in this thread (even retweeting 3 of your points). But I take major issue and strongly disagree with your framing of "likeliest outcomes." @AlexSteffen has a pointed thread on this: