When 2023 began, it seemed likely to be just one more year in the ongoing collapse of the world’s climate system. We were at the tail end of a long La Niña cold period in the Pacific, which meant that, although global temperatures had been near record levels for the past few years, they hadn’t quite topped 2016, the period of the last strong El Niño, which brought the hottest year to date—not to mention considerable havoc from Australia to Alaska.

Amid signs of that Pacific warm current starting to build anew, climatologists looked ahead to nextyear as the time when all hell might break loose. Experts said it was possible that in 2024 we could go past 1.5 degrees Celsius above pre-industrial temperatures—the mark that we had pledged to try to avoid at the Paris climate summit just eight years ago.

Instead, dire things began happening much, much sooner. This spring, the keepers of various data sets pointed out that sea-surface temperatures around the globe were setting records. In July, a buoy off the Florida Keys recorded what some meteorologists believe is the highest marine temperature ever measured, setting in at 101.1 degrees, which is right about where people keep their hot tubs. That extreme heat soon moved onshore; because the northern hemisphere has more land than the southern, this is always the time of year when consolidated global temperatures reach their height. And on July 3rd scientists reported that, if you averaged in all the earth’s weather stations, ships, ocean buoys, and satellites, as an expert explained to the Washington Post, the planet had recorded the hottest day in the history of measurements. Thermometers stretch back only a few centuries, but scientists are good at assembling proxy markers from glacial cores and lake sediments; they said that this may have been one of the hottest days in at least a hundred and twenty-five thousand years, which takes us about back to the point when people began using shells as decorations. July 4th was hotter, and then July 6th broke the record again. As for the year as a whole, data from the World Meteorological Agency show that, as the U.N. Secretary-General, António Guterres, told the global climate talks in Dubai last week, we can safely say, even with weeks to go, that 2023 will take the title.

The northern hemisphere began, as always, to tilt away from the sun as the year wore on, and the absolute average temperatures began to decline from those all-time peaks. But climatologists have another way of keeping track—they measure deviations from the norm for a particular date, comparing, say, September of 2023 with all the other Septembers for which we have records, and with the baseline for Septembers from the period before the Industrial Revolution had begun to warm the world. And in September we, in fact, went past that 1.5-degree mark. This would be an incredibly grim and remarkable milestone, except that in November, on the Friday before Thanksgiving to be exact, we also went past two degrees Celsius above the pre-industrial baseline. Because the Paris accords—again, signed just eight years ago—committed the world to “holding the increase in the global average temperature to well below 2°C above pre-industrial levels,” this was a signal moment. It didn’t mean that we’d utterly failed—the way these things are officially recorded, it will take several years for meteorologists, averaging annual temperatures over a two-decade span, to conclude that we’ve passed 1.5°C for good—but it was stunning. Almost no one had predicted that it could come this quickly; by autumn, we were living in a world far different than any that human civilization had known. And not a pleasant one: in the United States, insured losses from thunderstorms and related hazards were set to top fifty billion dollars for the first time in a single year, and in Canada wildfires had smashed records (and produced triple the amount of carbon dioxide that all the heating and cooking and flying and driving and cooling that Canadians will do this year).

The damage from climate disasters was obviously infinitely worse in poorer parts of the world—in September, a record rainfall in Libya destroyed two dams and washed more than ten thousand people out to sea—but, as the smoke from the Canadian wildfires drifted down over the political and economic power corridor of Atlantic America, producing some of the worst air ever measured in Washington, D.C., there was the unmistakable stench of political failure. Having ignored the warnings that Jim Hansen, the most farseeing of climatologists, offered in testimony before the Senate thirty-five years ago, we were now seeing in real time what that negligence wrought: the jet stream and the Gulf Stream faltering, and heat waves so enormous and unprecedented that even the otherwise unstoppable Taylor Swift had to postpone a concert in Rio, as the temperature topped a hundred and six degrees. Cruel summer, indeed. Cruel year.

And yet something else happened in 2023. Almost simultaneous with the breakout in temperature, there was a breakout in the installation of renewable energy, especially solar power, around the world. The story of the past thirty-five years was that we’d clearly decided as a society that it wasn’t worth spending enough money to forestall climate change. But the cost of clean energy has dropped so far that it is now possible that saving the planet might be a corollary of saving cash. This ongoing drop in price is more than a decade old, but sometime in the past few years it crossed an invisible line, making it cheaper than hydrocarbons, and this was the year when that reality finally translated into dramatic action on the ground. By midsummer, just as the world was seeing those record temperatures, it was also seeing the installation of about a gigawatt’s worth of solar panels a day—that is, we were installing the equivalent of a nuclear power plant every twenty-four hours, but spread out, instead of in one place.

A large number of those solar installations were going up in China, the world’s primary consumer of energy, but there were also heartening increases in the nations of the European Union (where the invasion of Ukraine has sparked a speedy push to get off Russian hydrocarbons) and in the U.S., where the first tranches of cash from President Biden’s Inflation Reduction Act are starting to spur clean-energy progress on all fronts. Renewable-energy installation has been increasing all decade, but so has fossil-fuel production, leading some to despair that clean energy would never truly undercut coal, oil, and gas. But this year the growth was so dramatic that, by year’s end, data were showing that total greenhouse emissions in the E.U. and U.S. were falling, and that if China’s emissions weren’t already in decline, they are expected to by the first quarter of next year, seven years ahead of schedule. It appears that you simply can’t put up that many solar panels without it beginning to change reality.

This explosive growth in clean energy—if it continues to accelerate exponentially—offers some hope of limiting the ultimate rise in global temperatures, which at the moment continue on a path toward a civilization-challenging rise of 2.5 or three degrees Celsius (or more, as Jim Hansen noted last month). Though rising interest rates have begun to interfere with all kinds of energy development, the price of solar energy continues to drop, and there’s no obvious limiting factor to its spread. (For example, according to an analysis, putting solar panels only in the cornfields currently devoted to growing ethanol could provide enough power for all electricity uses in America.) There are plenty of other technologies we’re spending money on, including small nuclear reactors and giant carbon-sucking machines, that may or may not someday play a role in the climate fight, but, for all the furor they produce, they seem unlikely to make much difference anytime soon. In the next few years, while the planet’s climate system teeters on the edge of breaking, it’s sun, wind, and batteries that matter. They’re cheap, and they’re ready.

But every bit of good news for the planet—such as November’s reporting from Reuters that sixty-eight planned gas plants had been abandoned or postponed around the globe because the cost of giant batteries coupled with renewable energy had rendered them obsolete—is bad news for the fossil-fuel industry. That industry, of course, has the wherewithal to fight back, and it is doing just that—domestically, by trying to undercut public acceptance of E.V.s, and internationally, by locking in export markets for fossil fuels. Last month, the Centre for Climate Reporting and the BBC reported that leaked briefing notes show that the United Arab Emirates had been aiming to use its presidency at this month’s global climate talks to make oil and gas deals around the world; meanwhile, Saudi Arabia is investing to help an American company bring back the supersonic jet, which burns three times as much fuel per seat when compared with normal airplanes, to passenger aviation. The single biggest example, though, is in the Permian Basin of Texas and New Mexico, where, despite declining domestic gas demand, the nation’s oil and gas companies are producing record amounts of it—and hoping to ship more and more of it overseas.

It’s clear that we won’t outright win the climate fight—right now, Somalia is suffering from epic floods, and Mexico City is restricting water use in the face of a tenacious drought. But, as renewable energy expands, the race should grow steadily more competitive, unless, of course, politics intervenes. A Republican victory in November would probably mean retrenchment—Donald Trump is a climate denier who in his first Administration withdrew the United States from the Paris accords, but even Nikki Haley was recently seen rebuking Ron DeSantis for trying to limit fracking in Florida. The world simply can’t afford another four-year time-out from aggressive climate action. This year showed the world on two paths, one utterly disastrous and the other at least a little redemptive; 2024 may decide which one we actually follow.