The nations of the world have agreed that allowing global average temperature to rise more than 2 degrees from preindustrial levels would be a disaster — that 2 degrees should be avoided at all costs, and that prudence suggests aiming for closer to 1.5 degrees.

Those targets, agreed upon in December in Paris, are now almost certainly out of reach. The fight to prevent dangerous climate change was lost last night with the election of Donald Trump.

I’m seeing a lot of whistling past the graveyard about this. "The main forces determining emission levels of heat-trapping carbon dioxide will be just as much out of President Trump’s hands as they were out of President Obama’s," writes New York Times columnist Andy Revkin. There’s only so much damage Trump can do, right? This is bigger than him. Right?

Sorry, but I don’t think so.

In the long-term, obviously, the forces shaping climate are bigger than any one president or administration. But we are past the point when long-term perspectives should comfort us. Limiting global temperature to 2 degrees would require large-scale, coordinated action now. And Trump means that isn’t going to happen.

So we won’t stop at 1.5 degrees. We won’t stop at 2 degrees. We’ll be lucky to stop at 3 or 4 degrees.

The story of US leadership on climate is dead

The truth is, hitting the 2-degree target (much less 1.5 degrees) was always a long shot. It would require all the world’s countries to effectively turn on a dime and send their emissions plunging at never-before-seen rates.

It was implausible, but at least there was a story to tell. That story began with strong US leadership, which brought China to the table, which in turn cleared the way for Paris. The election of Hillary Clinton would have signaled to the world a determination to meet or exceed the targets the US promised in Paris, along with four years of efforts to create bilateral or multilateral partnerships that pushed progress faster.

With steady leadership, the US and China would exceed their short-term goals. Other countries would have their willpower fortified and steadily ratchet up their commitments. All this coordinated action would result in a wave of clean energy innovation, which would push prices down lower, which would accelerate the transition.

The promise of US leadership was never about tons of US emissions; they are only 15 percent of the world’s total. (Though, as Chris Mooney notes, pledged US reductions accounted for about 20 percent of total reductions pledged in Paris.) It was about the US acting as a catalyst that sparked a virtuous, self-reinforcing cycle of escalating ambition, eventually building up the momentum necessary for a chance at 2 degrees.

That story is gone now. Dead. The US will not provide leadership — it will be an active, and very powerful, impediment. Under unified Republican leadership, progress on lowering emissions in the US will halt and reverse and US participation in international efforts to combat climate change will cease. (I will have more to say on the scope of the coming Republican policy disaster in another post.)

2020 is the only object for optimism

Yes, there will still be plenty of action to cheer. California and other West Coast states will continue to move forward, as will New York and a few more. Cost reductions in clean energy will continue, though they will likely slow down. The broad, tidal forces pushing for decarbonization will continue. But speed is of the essence, and the best chance for speed is now gone.

For all its troubles, the US is an indispensable leader of the free world. Its official posture is now going to be hostile to climate action.

Under those circumstances, the story about the world unifying to take bold, dramatic action on climate change, beyond what was pledged in Paris, has gone from unlikely to utter fantasy. The best climate activists can hope for is that Trump loses in 2020 in a giant Democratic wave that involves redoubled commitment to climate action.

But even in that wildly optimistic case, the chance of limiting temperature to 1.5 or 2 degrees is, for all intents and purposes, gone. There’s going to be severe, dangerous climate change. Millions of people will suffer.

The larger climate struggle is not over, of course. It never will be — 3 degrees is much worse than 2 and 4 much worse than 3. The fight goes on. But it is time to honestly acknowledge our failure and grapple with its consequences.

We won’t avoid dangerous climate change. That’s what the US decided last night. There’s no point pretending otherwise.