The Conference of Parties COP26 climate talks have agreed to get countries to strengthen their emissions-cutting targets for 2030 by the end of next year in a bid to limit dangerous warming.
Ministers and negotiators at the UN summit in Glasgow have also sent a signal on the shift away from the world's dirtiest fuel, with a deal calling for efforts to escalate the "phase down" of unabated coal, as well as the phasing out of inefficient fossil fuel subsidies.
The Glasgow Pact was watered down at the last minute - following a push by India and China - from escalating the "phase out" of unabated coal, to "phase down", prompting angry responses from European and vulnerable countries.
But it is the first explicit mentions of fossil fuels in a UN climate agreement that was the result of two weeks of tortuous negotiations that had to be extended for an extra day.
The deal aims to keep limiting global warming to 1.5C above pre-industrial levels "alive" or within reach, in the face of a huge gap between the action countries are taking and what is needed to meet the goal.
In the wake of the agreement being gavelled through - more than 24 hours after the official finishing time of the conference, there were warnings that the 1.5C goal was "on life support".
As the final deal was clinched, a tearful Alok Sharma, Britain's president of the COP26 summit, said: "I apologise for the way this process has unfolded. I am deeply sorry," before banging down his gavel.
Later, he told reporters that he wished he had been able to preserve the originally agreed language on phasing out coal power in the Glasgow climate deal.
"Nevertheless, we do have language on coal, on phase down, and I don't think anyone at the start of this process would have necessarily expected that would have been retained."
Minister for the Environment Eamon Ryan said that while the deal "gives us a chance of keeping 1.5 degrees alive", the last minute agreement on coal as "deeply disappointing".
He added: "The last minute deal on coal was deeply disappointing but we had to agree a deal. We can no longer delay. It brings momentum at home and has to deliver climate justice for the world."
Agreement has been reached at #COP26 in Glasgow. It gives us a chance of keeping 1.5 degrees alive. The last minute deal on coal was deeply disappointing but we had to agree a deal. We can no longer delay. It brings momentum at home & has to deliver climate justice for the world. pic.twitter.com/TI8E9ayMxu— Eamon Ryan (@EamonRyan) November 13, 2021
Climate activist Greta Thunberg dismissed the final agreement as "blah, blah, blah".
Antonio Guterres, Secretary General of the UN, said the outcome of COP26 was a "compromise" that reflected the interests, contradictions and state of political will in the world today.
"It's an important step, but it's not enough. It's time to go into emergency mode. The climate battle is the fight of our lives and that fight must be won."
The #COP26 outcome is a compromise, reflecting the interests, contradictions & state of political will in the world today.— António Guterres (@antonioguterres) November 13, 2021
It's an important step, but it's not enough.
It's time to go into emergency mode.
The climate battle is the fight of our lives & that fight must be won. pic.twitter.com/NluZWgOJ9p
He warned: "Our fragile planet is hanging by a thread. We are still knocking on the door of climate catastrophe."
The President of the EU Commission has described COP26 as "a step in the right direction". Ursula von der Leyen added: "1.5 degrees Celsius remains within reach; but the work is far from done."
EU Executive vice president Frans Timmermans said he was "disappointed" that the language on coal had been diluted.
"It is no secret to this gathering that the European Union would have wanted to go even further than the initial text in the cover agreement on coal," he admitted.
British Prime Minister Boris Johnson has tweeted about the "serious breakthroughs" made at Cop26 in Glasgow.
He said: "We've made serious breakthroughs @COP26. We've kept 1.5 alive and made huge progress on coal, cars, cash and trees.
"And while there is still so much that needs to be done to save our planet, we'll look back at COP26 as the moment humanity finally got real about climate change."
Amanda Mukwashi, chief executive of Christian Aid, said: "We were told that COP26 was the last best chance to keep 1.5C alive, but it's been placed on life support.
"Rich nations have kicked the can down the road and with it the promise of the urgent climate action people on the front line of this crisis need."
Alok Sharma had earlier told the delegates from nearly 200 countries faced a "moment of truth for our planet, for our children and our grandchildren. So much rests on decisions taken collectively".
Much-threatened island states including Fiji, the Marshall Islands and Tuvalu all signalled their support, despite pushing for much more financial support as they risk being swallowed by rising seas.
India's environment minister Bhupender Yadav earlier told delegates that developing countries had the "right to their fair share of the global carbon budget and are entitled to the responsible use of fossil fuels".
Greenpeace International chief Jennifer Morgan told AFP that the language on fossil fuels "is far from what is needed but sends a signal - I dare countries to take that out of the text right now".
"The US has to support the most vulnerable on the issue of loss and damage. They cannot avoid this issue any longer. Nor can the European Union," she added.
"I would call on President (Joe) Biden to do what's right, and support the most vulnerable in helping them deal with their losses."
We need your consent to load this rte-player contentWe use rte-player to manage extra content that can set cookies on your device and collect data about your activity. Please review their details and accept them to load the content.Manage Preferences
Although host Britain said it wanted COP26 to keep the 1.5C temperature cap in reach, a UN scientific assessment last week said countries' latest climate plans put Earth on course to heat 2.7C.
Today's text noted "with deep regret" that wealthy nations had also failed to stump up a separate annual sum of $100 billion they promised over a decade ago. It urged countries to pay up "urgently and through 2025".
It also promised to double finance to help developing countries adapt to rising temperatures by the same date.
But developing nations said it was unfair for the summit to produce an unbalanced agreement heavily weighted toward "mitigation" - how economies can ditch fossil fuels and reach net-zero emissions by 2050.
They wanted specific instruction on how they can meet the bill of decarbonising while also adapting to the natural disasters supercharged by global warming.
The two weeks in Glasgow saw a number of high-profile announcements from world leaders, such as a commitment to slash methane emissions by 30% by 2030.
It also witnessed mass protests against what activists said was a dangerous lack of urgency.
Additional reporting: Conor Macauley