After tense and protracted negotiations, delegates at the UN climate conference COP28 have agreed on a deal that calls on countries to transition away from fossil fuels. It is the first time that nations have agreed to such a transition, and marks a major step forward in climate ambitions. But delegates have warned that parts of the text are still not strong enough and that the real work of reducing greenhouse gas emissions is all still ahead of us.

“While nobody here will see their views completely reflected, the fact is that this document sends a very strong signal to the world,” US climate change envoy John Kerry said in a speech at the close of the conference. “We have to adhere to keeping 1.5 [degrees Celsius of warming] in reach,” he said, referring to the climate target set out in the Paris Agreement in 2015.

Going into the conference, many delegates had hoped that the final deal would ask countries to phase out fossil fuels altogether—perhaps an unlikely prospect given that this COP was hosted by the United Arab Emirates, a major oil-producing state and OPEC member. An earlier draft of the agreement was greeted with widespread disappointment as it contained only a weak reference to “reducing both consumption and production” of fossil fuels and a list of actions countries “could” take to reduce emissions.

The final agreement ramps up the ambition from this earlier draft, specifically calling for “deep, rapid, and sustained reductions in greenhouse gas emissions” that would keep global heating to below the 1.5 degrees Celsius target. The text also calls for a tripling of renewable energy capacity by 2030 and substantial reductions in non-carbon dioxide emissions globally by 2030—gases such as methane, which has a very high global warming potential.

“It’s a brilliant turnaround from the text two days ago, and the negotiators have pulled a rabbit out of the hat,” says Piers Forster, interim chair of the Climate Change Committee in the UK. “By dropping the controversial language on phase out and unabated [fossil fuels], they have been able to include language on the necessary transition away from fossil fuels this decade. This gives all 198 countries the mandate to go home and deliver strong domestic policies to affect the transformative change.”

As the final text has to be agreed by every party at the conference, this agreement is full of compromises that will leave many countries disappointed. “This was the best deal that was politically possible,” says Jennifer Allan, a senior lecturer in international relations at the University of Cardiff who is at COP28. “Countries are relatively equally unhappy.”

“We have come to the conclusion that the course correction that is needed has not been secured. We have made an incremental advancement over business as usual, when what we really need is an exponential step change in our actions,” Samoa representative Anne Rasmussen, speaking on behalf of the Alliance of Small Island States, told the conference after the final decision.

The stakes at this year’s conference were more significant than at most COPs, says Forster. It was the first time that countries came together to publish the global stocktake—an accounting of how much progress countries are making towards the goals of the Paris Agreement and where further action is needed. The global stocktake also helps countries refine their own plans for reducing emissions, which are submitted to the United Nations Framework Convention on Climate Change every five years.

These five-year frameworks and the global stocktakes are a critical part of what is known as the “ratchet mechanism”—the idea that the ambitions stated in the Paris Agreement are ratcheted up over time to bring the world closer to achieving the goal of keeping warming to well below 2 degrees Celsius. The agreement made at COP is not legally binding, but countries should use it to inform their own climate plans and reduce their own emissions in line with the ambition set out in the final text.

“There are gaps—especially on finance for adaptation—and loopholes—but the ultimate direction of travel is clear: the fossil fuel era is ending,” said Alex Scott, programme lead at climate think-tank E3G in an emailed statement.

There have been other more promising outcomes from COP28. The conference opened with the agreement of a loss and damage fund to help developing countries respond to climate harms. The final text of the summit urges developed countries to continue to provide support to address loss and damage in line with decisions made at the summit.

But the real work of reducing emissions, and actually delivering on the aims of these agreements, is still to come. This COP agreement marks a successful last-minute political compromise, but it remains to be seen whether it will deliver the change in emissions and finance that are desperately needed. “This is the best we can do,” says Allan. “The question now is: Is it going to be good enough?”