Diplomats from around the world have agreed a major climate deal after two weeks of United Nations talks in Poland.

But climate campaigners warned the deal – effectively a set of rules for how to govern the 2015 Paris climate accord – agreed between almost 200 countries lacked ambition or a clear promise of enhanced climate action.

Activists cautiously welcomed elements of the plan, saying “important progress” had been made on ensuring that efforts to tackle climate change by individual nations can be measured and compared.

But environmental groups were also highly critical of the agreement, warning it lacked ambition and clarity on key issues, including financing for climate projects for developing countries.

The COP24 deal, which is aimed at providing firm guidelines for countries on how to transparently report their greenhouse gas emissions and their efforts to reduce them, was confirmed on Saturday evening after talks overran from Friday.

The agreement establishes rules to govern the 2015 Paris climate accord, which includes a goal of capping global temperature increases at no more than 1.5C.

However scientists say emissions of gases such as carbon dioxide need to drop sharply by 2030 to prevent potentially catastrophic global warming.

And the meeting postponed decisions on pledging more ambitious action to fight global warming and on regulating the market for international carbon emissions trading.

Jennifer Morgan, executive director at Greenpeace International, said: “A year of climate disasters and a dire warning from the world’s top scientists should have led to so much more.

“Instead, governments let people down again as they ignored the science and the plight of the vulnerable.

“Recognising the urgency of raised ambition and adopting a set of rules for climate action is not nearly enough when whole nations face extinction.”

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Ms Morgan added: “Without immediate action, even the strongest rules will not get us anywhere. People expected action and that is what governments did not deliver. This is morally unacceptable.”

The talks in Poland took place against a backdrop of growing concern among scientists that global warming is proceeding faster than governments are responding to it.

“Through this package, you have made a thousand little steps forward together,” said Michal Kurtyka, a senior Polish official chairing the talks.

But Gareth Redmond-King, head of climate change at WWF-UK, said world leaders were in a “state of denial” about the problem.

“They’ve made important progress, but what we’ve seen in Poland reveals a fundamental lack of understanding by some countries of our current crisis,” he added.

“Luckily, the Paris Agreement is proving to be resilient to the storms of global geopolitics. Now we need all countries to commit to raising climate ambition before 2020, because everyone’s future is at stake.”

A recent report by the Intergovernmental Panel on Climate Change, or IPCC, concluded that while it’s possible to cap global warming at 1.5C by the end of the century compared to pre-industrial times, this would require a dramatic overhaul of the global economy, including a shift away from fossil fuels.

Alarmed by efforts to include this in the final text of the meeting, the US, Russia, Saudi Arabia and Kuwait blocked an endorsement of the IPCC report midway through this month’s talks in the Polish city of Katowice.

That prompted an uproar from vulnerable countries like small island nations and environmental groups.

The final text at the UN talks omits a previous reference to specific reductions in greenhouse gas emissions by 2030, and merely welcomes the “timely completion” of the IPCC report, not its conclusions.

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Li Shuo, a senior policy adviser at Greenpeace, said the agreement marked a significant step forward in the fight against climate change.

“If Paris set the destination, the rulebook is the roadmap to get there,” he said. “We’ve now got a solid rulebook with binding common rules to ensure that climate actions can be compared and the concerns of vulnerable countries taken into account.

“These rules now provide a backbone to the Paris Agreement and must be strengthened in coming years.”

Despite Donald Trump’s decision to pull out of the Paris climate accord and promote the use of coal, the US was praised for its efforts to close potential loopholes that could allow countries to dodge their commitments to cut emissions.