On Thursday, President Donald Trump officially announced that the United States will backpedal on its commitment to the Paris Agreement to curb carbon emissions as a way to stop planet’s gradual warming. It has provoked widespread condemnation from environmentalists, defiant statements from European leaders, and even the much publicized exit of Elon Musk from White House advisory councils.

The world’s climate activists have been fighting this kind of top-down opposition since the very beginning of this quest. The Paris Agreement wasn’t build overnight and its ongoing legacy can’t be erased that quickly, either.

10. The UN says climate change is a problem (1992)

The United Nations Framework Convention on Climate Change (UNFCCC) was the first really successful attempt to get the entire world on board to deal with climate change. Things felt a bit less urgent all the way back in ‘92, but scientists were already sounding the alarm with their boring “graphs” and “charts.” As a result, though the world did pretend to listen to these calls of alarm, the very general UNFCCC commitment to addressing carbon output doesn’t have much in the way of teeth. As a result of that, it was adopted by pretty much everybody. The UNFCCC does, however, have a provision that it should be revisited over the years. And boy, was it ever.

9. The world decides that two is the magic number (1995)

Meeting in Berlin, the first Conference of Parties (COP-1) to the UNFCCC basically had to decide on some definitions. How much of a reduction in carbon emissions is a big reduction? How much of a rise in global temperatures is considered a threat? COP-1 is where the world first developed the idea of trying to keep the globe from warming by more than two degrees Celsius, specifically. It wasn’t picked because 1.9 degrees is just fine, but the tug-of-war between climate science an economic self-interest settled on two as the number, and so that’s what we have now. Though it didn’t propose much in the way of real regulations, through its long-standing recommendations this may be the most influential of the older climate meetings.

8. The Kyoto Protocol is signed… for the most part (1997)

The Kyoto Protocol was the U.N.’s attempt to make some portion of the UNFCCC legally binding for signatories. It set targets for reductions in climate emissions, and it expected more of more wealthy nations — which makes sense, but remember that wealthy nations are also the ones with the most vested interest in the status quo. Its targets have been described as unambitious by climate activists, and its enforcement weak, yet perhaps because it didn’t shoot for the stars, Kyoto was eventually signed and ratified by virtually every nation on Earth. The glaring exception? The United States, which found even a general commitment to lowering emissions too threatening to industry.

7. Copenhagen negotiations collapse (2009)

The world tried hard to get a climate agreement in Copenhagen in 2009 but, obviously not hard enough. This meeting has been criticized for employing a top-down approach, and dictating terms to poorer countries, leading them to walk way in frustration. The backlash against this failure helped to spur the more democratic approach in Paris, years later, but in the short term Copenhagen-born public cynicism slowed the environmentalist movement’s progress significantly. It would take years of continued accumulation of data and public outcry over the effects of climate change itself to slowly restart the gears of bureaucracy.

6. A new round of negotiations begins at COP-17 (2011)

This is typical of how international frustration over failures like Copenhagen can lead to later agreements: slowly. With many Kyoto provisions expiring, the U.N. held its COP-17 climate conference in 2011. It was here that the world finally managed to the incredible feat of agreeing… to someday make an agreement. Signing onto something called the Durban Platform, every major polluter said in writing that they would figure out the terms of a legally binding climate treaty by 2015, to go into effect no later than 2020. It also put the target of a two-degree warming maximum into writing.

5. Stalling, anger, and more stalling (2011-2015)

For years, even the idea of negotiations on further binding climate regulations could evoke anger, and self-interested throwing of wrenches into gears. At COP-19, China and the G77 group of developing nations led a total of 132 poorer countries in a mass walk-out on the proceedings. Talks were sometimes opposed on the basis that they were anti-business, other times on the basis that they were anti-poor, and yet others on the basis that they were anti-growth in quickly developing nations — which, if you’re keeping track, covers literally everyone. In the end, this period ended due to the constant, depressing parade of doomsday headlines on the newest findings of climate science.

4. Final Paris negotiations begin (2015)

At COP-21, in 2015, negotiations began on what would become the Paris Agreement. At the Le Bourget airport, notoriously tense negotiations were herded forward by a group of “ambitious” island nations with the most to fear from rising sea levels. Limits were again locked to a particular country’s wealth and realistic ability to change, but this time the world had a much better understanding of just how much climate change itself threatened their interests. Everybody, from China to Russia to the United States itself, finally seemed genuinely interested in finding an accord. And lo’, find one they did.

3. Virtually the entire world signs the Paris Agreement (2015)

Around the world, millions took to the streets to express their support for a strong agreement; the Global Climate March alone accounted for at least 750,000. Obama was also desperate for a left-friendly legacy to help end of his term, and together with public pressure, the U.S. helped push these contentious negotiations through. By the time the dust had settled, the only major nations that had not signed the agreement were Syria and Nicaragua — and Nicaragua’s objection was that the agreement wasn’t strong enough. Around the world, environmentalists did not say, “Mission accomplished,” but they did breathe a slow sigh of relief. This looked like real, meaningful progress — barring something totally unexpected, of course…

2. Trump elected after promising to pull out of Agreement (2016)

Nobody can know how important Trump’s opposition to the Paris agreement really ended up being to his eventual win, but his opposition to environmental regulations has been one of his most consistent qualities as a candidate and politician. Both before and after election, Trump has railed against industrial waste disposal regulations, the protections provided to national parks, and the climate agreements signed during Obama’s tenure. Though many doubted he would follow through on his pledge to remove America from the Paris accords, there was never any real reason to do so; Trump has never given any indication of truly wavering on this one, particular, commitment.

1. Trump pulls the U.S. out of the Paris Agreement (2017)

Finally, Trump followed through. He didn’t follow through on his pledge that nobody would lose their health insurance if he repealed Obamacare, nor on the pledge to label China as a currency manipulator — but he sure has stuck to his guns on Paris. Just what impact this will have is up in the air right now, but it’s pretty easy to imagine some early implications.

At the end of the day, environmentalists have the simple physical reality of climate change on their side, and that’s why the trend will always be toward more action in the long run. The story of global climate agreements is the story of the slow triumph of evidence over ignorance and self-interest. All we learned this week is that the story still is far from over.

Photos via Getty Images / Jack Taylor, Getty Images / Chip Somodevilla, Getty Images / Kevin Frayer