The idea of letting warming approach 2 degrees increasingly seems disastrous in this context.
Parts of the planet, like the Arctic, have already warmed beyond 1.5 degrees and are seeing alarming changes.
Major die-offs have hit coral reefs around the globe, suggesting an irreplaceable planetary feature could soon be lost.
And that was before the United States, the world's second-largest emitter, decided to try to back out.
This is why scenarios for holding warming to 1.5 degrees require rapid and deep changes to how we get energy.
And that's just the point - 1.5 degrees is still possible, but only if the world goes through a staggering transformation.
Such technologies do not exist at anything close to the scale that would be required. »