There’s a strange circularity to writing about climate change. Every few months or so, a new report comes out from an esteemed scientific body; each time, the conclusions are grim: the planet continues to warm steadily; each time, there are more severe observed effects at lower levels of warming than scientists had previously predicted. Every time one of the well-meaning scientists who wrote the report says something like “the final tick box is political will.” Another says something like “it’s a line in the sand and what it says to our species is that this is the moment and we must act now.” Every time we don’t. Instead everyone freaks out for a few days, and then something else happens that everyone freaks out about instead (myself included). Meanwhile, the cliff grows closer and closer.

Yesterday was one of those days: a new United Nations Intergovernmental Panel on Climate Change (IPCC) report — the gold standard of climate research, produced by an international body of scientists aggregating thousands of scientific studies — estimated that by 2040 the earth will have warmed 1.5º C (2.7º F) from the “pre-industrial levels,” with world-changing effects.

A 1.5º rise is typically considered the threshold of caution, and 2º the threshold of safety, though even that is increasingly in doubt: many of the effects scientists once thought would only kick in at 2º or higher now look likely to begin much sooner. The oceans will get more acidic and coral will die. Hundreds of millions of poor people will get poorer. Millions of people will be forced to leave their homes and migrate in search of new ones. There’s still time to keep warming to 2º, or even 1.5º — but it will take major action on a very short timescale. The news was bad but familiar.

But something else happened yesterday: the economist William Nordhaus won the Sveriges Riksbank Prize in Economic Sciences — aka the “Nobel Prize in Economics.” Nordhaus is known for his work on environmental economics and specifically the economics of climate change, on which he’s written widely. But Nordhaus is no climate hero — he’s consistently downplayed the risks that climate change poses and chastised other scholars for alarmism. In particular, Nordhaus has been an advocate for using a high “discount rate” in climate economics. Discount rates are an economic tool used to value the future; a high rate values the future less than the present.

To explain why this matters, I have to turn to an internal debate among economists. (Bear with me.) In 2006, the British economist Nicholas Stern produced a major report on climate change at the behest of the British government, known as the “Stern Review on the Economics of Climate Change.” Stern argued in favor of decisive, immediate action to reduce carbon emissions as soon as possible. He proposed a very low discount rate — one that suggested that the high costs of action in the present were worth it. “The benefits of strong, early action on climate change,” Stern wrote, “far outweigh the costs of not acting.”

Nordhaus criticized Stern for overreacting. Stern’s discount rate, he said, was radically low. Instead, Nordhaus suggested that the future should be discounted more heavily — that is, that the costs of action in the present should be weighted more heavily than future benefits. It would be better for everyone, present and future, to gradually impose the costs of climate mitigation and keep growing the economy in the meantime: future generations would be richer, and therefore better able to adapt to climate change. Nordhaus had been making this argument for years. Stern’s report was so important precisely because it broke with the pro-gradualist consensus that Nordhaus had built.

Nordhaus’s position, by contrast, was perfectly in keeping with the principles of mainstream economics. There, a relatively high discount rate reflects the expectation of robust economic growth. Since the economy could be much bigger in 2050, the reasoning goes, it is more expensive to spend on climate action now than it would be then.

Most economists at the time saw climate change as a distant problem — something that would affect people centuries into the future, people several generations removed from the present. Projects to reduce carbon emissions were judged on their rate of return — if they underperformed relative to the market, it would be better to simply invest the money, which would make future generations richer and therefore better able to adapt. By this logic, spending money to address climate change might actually harm future generations by failing to maximize growth.

If this sounds crazy, well, it is. The tools at economists’ disposal were growth and efficiency, and with them they hammered away at every new problem. (Just yesterday Nordhaus told his undergraduate economics class, “Don’t let anyone distract you from the work at hand, which is economic growth.”) While climate scientists projected a future of severe climate shocks causing social and economic crises, Nordhaus projected smooth curves of gradual, efficient change, wherein business as usual could continue more or less uninterrupted.

Of course, economists aren’t the real reason why we haven’t taken decisive action on climate change. We can still blame fossil-fuel companies, the Republican Party, and Wall Street (i.e., capitalism) for that. And Nordhaus has at least taken environmental harm seriously — for an economist.

But if there was a time when economists did have political sway, it was in those pre-2008 days when economics was still thought of as the master science. And Nordhaus’s admonishments to Stern and climate activists for moving too fast have given cover to those who would slow the pace of climate action. They have legitimized incremental, gradual responses to climate change. They have justified dismissing climate scientists’ warnings as alarmism. They have done what they promised: they have discounted the future.

But just a decade later, we’re running out of future. According to the IPCC report, for global temperatures to rise only 1.5 degrees C, global emissions must drop 45 percent from their 2010 levels in the next twelve years — an extremely heavy lift. (Nordhaus — not a climate scientist — has suggested that 1.5 degrees is overly cautious.) So it was particularly perverse to award a major prize to someone whose work has consistently called for slower, more measured action on a day when climate scientists insisted we need to speed up.

What does that mean for us today? Five years ago I wrote about the problem of a left facing a drastically foreshortened future. Unhappily, most of what I wrote still stands — except today, climate conditions look a lot worse. What’s brighter today, though, is the Left itself: it has grown mightily in the past few years. The clean energy technologies we’ll need are also far cheaper and more sophisticated than projected even a few years ago; with massive public action, it’s more possible to imagine replacing fossil fuels. But the Left that would make the transition happen isn’t yet mighty enough. Despite some important victories, we’re still on the defensive, in the US and around the globe.

What’s changing about the climate news cycle, meanwhile, is that each new report says more blatantly that addressing climate change “will require unprecedented transitions in all aspects of society.” Even the soberest of scientists (not economists!) will now tell you that stopping climate catastrophe requires remaking the global economy and redistributing global wealth. More and more people are coming around to the position that something major has to happen, even if they aren’t entirely clear on the politics.

This is a place where the Left can and must step in: we need to replace the narrowly economistic orientation towards growth that has marked the discount rate debates with a bold vision of a good and livable future — and a political program to match. To start, that means insisting on a publicly funded clean energy transition on a rapid timeline; free public transportation; a major green jobs program oriented towards care and reduced work; public spending on adaptation in vulnerable communities at home and abroad; welcoming migrants and refugees; and more generally, a society where a good life is valued more highly than the market rate of return.

We still have a very long way to go, and the urgency of climate change won’t just cut through all the Gordian knots of politics overnight. But that urgency nevertheless has to spur our political aspirations and expectations.

Nothing we need to do to stop climate catastrophe is politically realistic. But what’s truly unrealistic is thinking that the future is just going to be brighter on its own, that future generations will solve their own problems. There’s no time left for Nordhausian incrementalism. The future — our future — is at stake.