Madrid: UN chief Antonio Guterres on Sunday said he was ‘disappointed’ by the outcome of the marathon climate talks in Madrid which ended with no deal on carbon markets, calling it a “lost opportunity” to fight global warming.

The longest UN climate talks ended here on Sunday with delegates from almost 200 countries, after two weeks of marathon negotiations, failing to come up with more ambitious targets to cut greenhouse gas emissions to fulfil the terms of the 2015 Paris agreement.

Despite holding the longest climate talks ever in 25 nearly annual editions, the negotiators left one of the thorniest issues for next summit in Glasgow – how to deal with carbon emissions.

“I am disappointed with the results of COP25. The international community lost an important opportunity to show increased ambition on mitigation, adaptation and finance to tackle the climate crisis,” Guterres said in a tweet after the plenary concluded.

The major climate summit brought together delegates of nearly 200 countries to finalise implementation of the 2015 Paris agreement to limit the rise in global temperatures to less than two degrees Celsius.

But competing national interests proved insurmountable despite global calls for action in the face of extreme weather phenomena and increasingly dire warnings from climate scientists.

“We must not give up, and I will not give up,” Guterres said.

“I am more determined than ever to work for 2020 to be the year in which all countries commit to do what science tells us is necessary to reach carbon neutrality in 2050 and a no more than 1.5 degree temperature rise,” the UN Secretary-General said.

Few countries came to this year’s talks with updated plans to reach the Paris agreement, even as the EU agreed its long-term target of reaching net zero emissions by 2050. Experts say more ambitious emissions cuts are needed globally if the Paris pledge is to be met.

“I have the hope that we can use this material to reach agreement at COP26,” said COP25 President Carola Schmidt on the draft decision on Article 6 of the Paris agreement.

Under the Article 6 of the Paris agreement signed in 2015, the countries had agreed to set up a global carbon market system to help developing countries decarbonise their economies at lower cost.

However, the countries have tried and failed to agree the rules governing this mechanism.

May Boeve, Executive Director, said “COP25 was a success for the fossil fuel industry – their interest have won, effectively blocking the process and undermining the end result”. is an international environmental organisation addressing the climate crisis.

“As time ran out, the COP looked more and more like a hostage situation inside a burning building – together with most negotiators, people and planet were held captive, as the fossil fuel industry and a few loud governments who have been delivering on their agenda took over the process.

“In the end, after forcing negotiators to keep at it for three days straight, they got what they wanted – a weakened text that kicks most of the big issues down the road to COP26,” Boeve said.

Debate on governance was pushed to the next year. On oceans and land, new UN work to commence on the ocean and climate change to consider how to strengthen mitigation and adaptation action; as well as in land and climate change adaptation related matters, said Jennifer Organ from Greenpeace International.

The governments need to completely rethink how they do this, because the outcome of COP25 is totally unacceptable. This COP exposed the role of polluters in politics and the youth’s deep distrust of government, as climate blockers like Brazil and Saudi Arabia, enabled by an irresponsibly weak Chilean leadership, peddled carbon deals and steamrolled scientists and civil society, she said.

“We need systemic change that people can trust, and the Paris agreement is just one part of the puzzle. Decision-makers now need to go home, regroup and think about how to move forward as we head into a critical 2020,” Organ said.

“I’ve been attending these climate negotiations since they first started in 1991. But never have I seen the almost total disconnect we’ve seen here at COP25 in Madrid between what the science requires and what the climate negotiations are delivering in terms of meaningful action by the youth,” said Alden Meyer, Director of Policy and Strategy, Union of Concerned Scientists.

Growing numbers of people around the world are demanding that their leaders take bold, ambitious action to tackle the climate crisis, he said.