Today marks the 10th anniversary of the Paris climate treaty, one of the landmark days in climate-action history. Attending the conference as a journalist, I watched and listened and wondered whether 194 countries could ever agree on anything at all, and the night before they did, people who I thought were more sophisticated than me assured me they couldn’t. Then they did. There are a lot of ways to tell the story of what it means and where we are now, but any version of it needs respect for the complexities, because there are a lot of latitudes between the poles of total victory and total defeat.
I had been dreading the treaty anniversary as an occasion to note that we have not done nearly enough, but in July I thought we might be able celebrate it. Because, on 23 July, the international court of justice handed down an epochal ruling that gives that treaty enforceable consequences it never had before. It declares that all nations have a legal obligation to act in response to the climate crisis, and, as Greenpeace International put it, “obligates states to regulate businesses on the harm caused by their emissions regardless of where the harm takes place. Significantly, the court found that the right to a clean, healthy and sustainable environment is fundamental for all other human rights, and that intergenerational equity should guide the interpretation of all climate obligations.” The Paris treaty was cited repeatedly as groundwork for this decision.
Ralph Regenvanu, Vanuatu’s special envoy for climate, said of the decision: “I choose my words carefully when I say that this may well be the most consequential case in the history of humanity.” Costa Rica’s Christiana Figueres, who presided over the negotiations that created that Paris climate treaty declared, with jubilation, on her podcast: “The reason why I am truly tearful is this is without a doubt, the most far-reaching, the most comprehensive and the most consequential legal opinion we’ve ever had.”
This case that ended in the world’s highest court began with 27 law students in the University of the South Pacific who in 2019, asked themselves what they could do about climate – and it’s not hard to imagine a “what can we do, we’re only students” or “what can we do, we’re from tiny remote nations” stance. Instead, they set out to take a case all the way to the international court of justice in The Hague, unimpeded by the conventional wisdom that they were nobody from nowhere. They needed a law firm, and they chose Blue Ocean Law firm, sticking with the Pacific island nations, with indigenous leadership, with the impacted global south. And they needed a country to be plaintiff and the island nation of Vanuatu stepped up. The unanimous court decision in favor of the litigants matters most of all in how it is implemented, either through direct cases or through its impact on nations that take notice and reduce their climate devastation before they’re brought to court.
It’s not widely known that most countries and negotiators went into the conference expecting to set a “reasonable” two-degree threshold global temperature rise we should not cross. As my friend Renato Redentor Constantino, a climate organizer in the Philippines, wrote:“The powerful exerted tremendous effort to keep a tiny number, 1.5, out of United Nations documents. 1.5 degrees centigrade represents what science advises as the maximum allowable rise in average global temperature relative to preindustrial temperature levels. It was the representatives of the mostly global-south nations of the Climate Vulnerable Forum who fought to change the threshold from 2 degrees to 1.5.”
I remember them chanting “1.5 to stay alive”, because two degrees was a death sentence for too many places and people. The officially powerless swayed the officially powerful, and 1.5 degrees was written into the treaty and has became a familiar number in climate conversations ever since. Even though we’ve crashed into that 1.5 threshold, far better that it be set there than at 2 degrees, in which case we might well be complacent in the face of even more destructive temperature rise.
It takes far more than storytelling to get where we need to go, but how we tell the stories is crucial. I asked the climate policy expert Leah Stokes of UC Santa Barbara about the impact of Paris and she told me: “When small island nations pushed for 1.5 degrees as the target, they also requested the IPCC [intergovernmental panel on climate change] write a special report on what policy would be required to get there. That report came out in October 2018, and rocked around the world with headlines like ‘we have 12 years’. It changed the entire policy conversation to be focused on cutting pollution in half by 2030. Then, when it came time to design a climate package, Biden made it clear that his plan was to try to meet that target. You can draw a line between small islands’ fierce advocacy through to the passage of the largest climate law in American history.”
That’s how change often works, how an achievement ripples outward, how the indirect consequences matter as well as the direct ones. The Biden administration tried to meet the 1.5 degree target with the most ambitious US climate legislation ever, the Build Back Better Act that passed Congress after much pressure and conflict as the Inflation Reduction Act. Rumors of the Inflation Reduction Act’s death are exaggerated; some pieces of its funding and implementation are still in effect, and it prompted other nations to pursue more ambitious legislation. In the US, state and local climate efforts, have not been stopped by the Trump administration. Globally not nearly enough has been done to stop deforestation, slash fossil-fuel subsidies, and redesign how we live, move, and consume.
The renewables revolution is a bright spot. It’s often overlooked because it’s incremental, technical, economic, and dispersed, and even its major milestones don’t receive nearly the recognition they should. When the Paris treaty was signed, renewables were overall more expensive than fossil fuel, and were not widely implemented. But the drop in cost and spread of solar has outstripped virtually all predictions. The energy-policy group Ember reports: “Record solar power growth and stagnating fossil fuels in 2025 show how clean power has become the driving force in the power sector. Historically a growth segment, fossil power now appears to be entering a period of stagnation and managed decline.” The International Energy Agency notes another 2025 landmark: “The electricity sector is now the largest energy employer, surpassing fuel supply for the first time, as the age of electricity gathers pace.”
Anyone who in 2015 accurately prophesied what the energy landscape would look like in 2025 would have been thought to be ridiculous, delusional, or crazy (just like anyone who said in, say, 1995 that the UK would close its last coal-fired plant in 2024 would have been). 2025 is the year that renewables outstripped coal as an energy source. Ancillary developments like battery storage technology and design improvements and innovations have led to widespread renewables adoption from Denmark (which gets only 10% of its electricity from fossil fuels) to Texas to Pakistan (where small-scale solar panels from China have led something of an energy revolution). Solar power is now so cheap and abundant in Australia that electricity is going to be free for three hours in the middle of the day.
Problems that the enemies of climate action liked to cite, such as the intermittency of sun and wind, have been addressed with battery storage. California now often produces more than 100% of its electricity needs through renewables, led by solar, in the daytime. The excess goes into the batteries so that the state literally runs on sunshine at night. California uses 44% less natural gas to produce electricity than it did two years ago. China is reducing its emissions because it’s speedily transitioning to renewables; earlier this fall, in the United Nations, for the first time it made an actual commitment to reduction targets; and for the last eighteen months its CO2 emissions have been flat or falling.
Is this good enough? Far from it, but we are, as they say, “bending the curve”: before Paris the world was headed for 4 degrees of warming; it’s now headed for 2.5 degrees, which should only be acceptable as a sign that we have bent it and must bend more and faster. In the best-case scenario, the world’s leaders and powers would have taken the early warnings about climate change seriously and we’d be on the far side of a global energy transition, redesign of how we live, and protection of oceans, rainforests, and other crucial climate ecosystems. But thanks to valiant efforts by the climate movement and individual leaders and nations, we’re not in the worst-case scenario either. Landmarks like the Paris treaty and the Vanuatu victory matter, as do the energy milestones, and there’s plenty left to fight for. For decades and maybe centuries it has has been too late to save everything, but it will never be too late to save anything.
This article was amended on 12 December 2025 to clarify that 2025 is the year renewables, not just wind and sun, outstripped coal as an energy source.
