The COP26 climate talks have finally reached agreement after running over by an extra day in Glasgow - but many leaders have hit out over "watering down" of measures.
The 197 nations taking part agreed to strengthen their emissions-cutting targets for 2030 by the end of next year following breakthrough talks.
They also agreed to accelerate efforts to "phase down" unabated coal and phasing out inefficient fossil fuel subsidies.
But environmental campaigners say the measures do not go far enough, with Greenpeace labelling the deal "weak" and activist Greta Thunberg saying "real work" would be done "outside these walls".
The Glasgow Pact was watered down at the last minute - following a push by India and China - downgrading the "phase out" of unabated coal, to "phase down".
This prompted angry responses from European and vulnerable countries.
COP President Alok Sharma, who appeared close to tears while delivering a closing address, said he understood disappointment around the deal.
He told delegates: "We met here under extraordinary circumstances and the negotiations have been far from easy. I can tell you that definitely."
The deal is, however, the first explicit mentions of fossil fuels in a UN climate agreement and has been hailed as a "building block" by the UN Secretary General.
The pact aims to keep limiting global warming to 1.5C above pre-industrial levels "alive" or within reach.
Delivering a scathing verdict, Ms Thunberg wrote on Twitter: "The #COP26 is over. Here’s a brief summary: Blah, blah, blah. But the real work continues outside these halls. And we will never give up, ever."
Labour leader Sir Keir Starmer said of the agreement at Cop26, that "there has been modest progress toward the challenges we face - which is important".
He added: "But we have seen too many promises for tomorrow, not the action that the climate emergency demands today. Boris Johnson bears some responsibility for that.
"Glasgow has been a missed opportunity - a summit too often of climate delay not climate delivery".
He accused the Prime Minister of not treating the summit with the seriousness it deserved, or building the trust that was critical to its success.
As details of the agreement were released, Greenpeace International Executive Director Jennifer Morgan said: “It’s meek, it’s weak and the 1.5C goal is only just alive, but a signal has been sent that the era of coal is ending. And that matters.
“While the deal recognises the need for deep emissions cuts this decade, those commitments have been punted to next year. Young people who’ve come of age in the climate crisis won’t tolerate many more outcomes like this. Why should they when they’re fighting for their futures?
“Glasgow was meant to deliver on firmly closing the gap to 1.5C and that didn’t happen, but in 2022 nations will now have to come back with stronger targets.
"The only reason we got what we did is because young people, Indigenous leaders, activists and countries on the climate frontline forced concessions that were grudgingly given. Without them, these climate talks would have flopped completely."
She added: "Our once stable climate is now breaking down around us, you see it every day in wildfires, hurricanes, droughts and melting ice. Time’s up, we’ve run out of road, and as a matter of self-survival we need to urgently mobilise to create irrepressible pressure that finally ends the era of all fossil fuels.”
Mr Sharma defended the progress made, saying it promoted "inclusive climate action".
He continued: "(The decisions) promote inclusive climate action, recognising the important role played by civil society, indigenous peoples, local communities, youth and other stakeholders.
"They compliment the impressive commitments and actions of all those who joined us in Glasgow, driving progress on coal, cars, cash and trees."
He added that he had been "struck by the determination" of delegates and said: "Each and every one of you and the nations you represent has stepped up here in Glasgow, agreeing to do what it takes to keep 1.5 alive. For that I am infinitely grateful."
UN secretary general Antonio Guterres said the approved texts from Cop26 were a compromise that took important steps - but added that the political will among leaders "was not enough to overcome some deep contradictions".
He warned: "Our fragile planet is hanging by a thread. We are still knocking on the door of climate catastrophe."
He called for an end to fossil fuels subsidies, a phase out of coal, a price on carbon, building resilience of vulnerable communities against the impacts of climate change and to make good on the long-promised 100 billion US dollar climate finance commitment to support developing countries.
He said: "We did not achieve these goals at this conference. But we have some building blocks for progress."
Earlier Emily Wright, a representative from Save the Children International, said: "I think the fact that they didn't close it at 6 o'clock, 8 o'clock last night shows that they might be committed to a sort of deal that works for everybody."
Naja Moretro, the head of the Norwegian Church Aid Youth Organisation, had a different view: "The texts have been getting weaker and weaker when it comes to clear language."
Mr Sharma opened up an informal plenary to take stock of the latest proposals, saying the conference had reached the "moment of truth for the planet, for our children, for our grandchildren".
In a potentially positive sign, China negotiator Zhao Yingmin told the plenary that the current draft of the deal is not perfect but that his team has no intention to reopen it.
But representatives of Tanzania and Guinea said they were disappointed that the draft did not do more to ensure poor, climate-vulnerable nations like theirs were getting adequate financial help to deal with global warming issues.
EU climate chief Frans Timmermans drew a rousing round of applause for his comments to the plenary, in which he asked countries to unite around the deal for the sake of "our children, our grandchildren."
"They will not forgive us if we fail them today," he said.
He opened his comments by saying the conference risked "stumbling in this marathon" a few steps before the finish if country delegations demanded new changes to the texts.
Mr Sharma said he understood the concerns of various parties, but warned against upsetting the current "delicate balance".
He said: "There is a fine and fragile green thread which is weaved around this balanced package. And I do think that if any of us tug, it will unravel all too easily."
He added: "I do think these texts are fully consistent with the goals of the Paris Agreement and the ultimate objective of the convention.
"So I do hope that we can leave this conference united, having delivered something significant for our people and planet - together as one."
US climate envoy John Kerry said he believed the deal "raises ambition on a global basis."
It came after heated protests in the summit venue and a desperate last-minute plea from islanders - who said they are “literally sinking” into the sea.
A draft text on Friday morning reaffirmed the goal to hold global warming “well below” 2C, and “pursue efforts” to keep it below 1.5C.
But with humans already causing 1.1C of warming to date, the world was on track for a 2.7C rise this century before COP.
And green campaigners were left furious after a draft watered down a pledge on fossil fuels - sparking fears it would be removed altogether by the final version.
Nations were going to "accelerate the phasing-out of coal and subsidies for fossil fuels". But this was weakened by specifying "unabated coal" and "inefficient subsidies".
A text “urging” countries to revisit and strengthen their targets next year was watered down into “requesting” they do.
The UK’s COP26 President Alok Sharma urged “a final injection of that can-do spirit" to get a deal over the line as a Friday evening deadline came and went.
Recent drafts added more on finance for poorer countries to adapt with climate change - and came after key side deals at the summit on coal and deforestation.
Nations are pledging $100bn a year for poorer countries by 2023, three years later than planned.
Leaders were also due to reconvene in 2023 - an admission this two-week summit of 197 nations was not enough on its own.
Mr Sharma said: "This is our collective moment in history, this is our chance to forge a cleaner, healthier, more prosperous world.”
Boris Johnson added: “We're in the final furlong - it's in the final furlong where the horses change places.”
But hundreds of furious activists from around the world marched through the sprawling COP26 venue, singing and chanting led by a group of indigenous activists.
They carried banners and red ribbons to represent the red lines crossed by negotiators - and two people were led away by police.
Mary Church, of Friends of the Earth Scotland, expressed “deep frustration" with the climate summit.
She said: "We are hurtling ever closer to reaching the critical 1.5C threshold.
"Climate change already impacts and threatens billions of lives."
And Tuvalu's representative received long applause in the main hall after saying: "Our land is fast disappearing, Tuvalu is literally sinking. We must take action now.
"This must be the defining moment - we must not fail.”
Boris Johnson - who was slammed for making only a day trip to the summit on Wednesday when talks faltered - implored world leaders: “If they can have the courage to do this deal, to agree the cover decision that's on the table today then we will have a road map that will enable us to go forward and start to remove the threat of anthropogenic climate change.
"We won't clinch it all at Cop but we can start."
But Shadow business secretary Ed Miliband said: “It will represent modest progress, but on climate modest progress isn't enough".
And John Kerry, the United States' climate envoy, described spending money on fossil fuel subsidies as "insanity".
Mr Kerry said: "Those subsidies have to go. We're the largest oil and gas producer in the world and we have some of those subsidies and President Biden has put in legislation to get rid of them.”
