After two weeks of haggling negotiators at the COP24 climate talks in Katowice in Poland entered their last scheduled day with many issues still undecided.

At issue is the precise rule book for how the Paris Climate Change Agreement agreed three years ago will be implemented, including how a country's emissions and commitments are to be measured and interpreted. 

While that may be a relatively straightforward issue for countries within the European Union, it is proving to be a highly controversial and difficult issue when 193 countries are involved.

There are also big arguments to be resolved about where the $100bn per year of climate finance promised by richer developed countries is to come from.

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With the United States pulling out of the Paris accord that issue of climate finance is now proving very difficult to resolve.

The third main issue at stake is how to ensure that nations ratchet up their commitment to take action to reduce their greenhouse gas emissions.

This was made particularly urgent by the publication of the IPCC report on the impact of 1.5 degrees of warming two months ago.

This showed that hundreds of millions of people and countless species face climate devastation if global warming is not contained to 1.5 degrees and also that greenhouse gas emissions need to be reduced three times faster than previously expected.

There is a growing expectation that the negotiations in Poland, which are due to finish later today, could yet spill over into the weekend.

Sources close to the COP24 talks said that delegates from nearly 200 nations were still far apart on several issues, from adopting the latest environmental science to how future climate action is funded.

The Conference of the Parties (COP) is the supreme body of the United Nations Framework Convention on Climate Change (UNFCCC).

Ministers must agree on a common rule book to make good on promises made by countries in the landmark 2015 Paris accord, which vowed to limit global temperature rises to below 2C.

But with the starkest warnings yet from scientists highlighting the need to drastically slash fossil fuel emissions within the coming decades in order to meet the safer cap of 1.5C warming, delegates were urged to act now or condemn at-risk nations to disaster.

"We are bearing the torch for those vulnerable to climate change," Hilda Heine, president of the Marshall Islands, told the conference.

"We represent a number of nations, like my own, that face extinction. Species of all kinds also face existential risk."

Dominating proceedings in the mining city of Katowice was debate around a major report by a UN body showing the clearest sign yet of the disaster awaiting mankind if politicians fail to act.

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The Intergovernmental Panel on Climate Change (IPCC) warned there was no hope of meeting the Paris temperature goals unless greenhouse gas emissions were slashed to net zero by mid-century.

Despite the UN climate change convention obliging nations to negotiate on the basis of the "best available science", four nations refused to "welcome" the IPCC findings at the talks.

Most nations want the IPCC science to inform the rule book and form the foundation of countries' future ambitions on climate action.

But the US, Saudi Arabia, Russia and Kuwait were accused of playing for time to boost their fossil fuel-dependent economies.

Host Poland has also come in for criticism from green campaigners for seeking permission to continue using coal for years in spite of overwhelming data that the opposite must happen.

"We do not have the comfort of time, but we have the will and we have power to achieve a compromise," Poland's COP24 president Michal Kurtyka told delegates last night as the final draft decision text was still being tinkered with.

The expectation is that talks will drag on until at least tomorrow, with a number of key issues still unresolved.

Additional reporting: AFP