Countries haven’t yet locked down a deal for how to cut greenhouse gas emissions as international climate negotiations go into overtime in Poland.

Negotiations for a deal on the rules that will implement the Paris climate agreement are continuing Dec. 15 at a two-week United Nations climate change conference.

Issues including greenhouse gas emissions accounting and commitments to deeper carbon cuts were said to delay the proceedings.

A final decision at the conference, which had been scheduled to end Dec. 14, was delayed into the afternoon and was expected to be delayed into the night.

Observer groups briefing reporters on background Dec. 15 said one of the biggest stumbling blocks was a question about how countries would account for their greenhouse gas emissions and whether they would be allowed to claim a pollution cut while also being able to use the same cut as an emissions credit given to another country.

Another sticking point among negotiators is what they refer to as “loss and damage"—how wealthy nations will assist less-developed countries with the impacts of climate change, the groups said.

The outcome of the conference will determine how countries are able to quell the onset of global warming, which presents an existential crisis for humanity, U.N. Secretary-General Antonio Guterres told delegates at the start of the Poland conference.

The significance of the rules is that they symbolize that countries that signed the Paris pact are committed to act on climate change, Jonathan Pershing, former U.S. State Department special envoy for climate change in the Obama administration, told Bloomberg Environment Dec. 14.

In addition to the rules for the Paris accord, the final package is expected to contain a political statement on “ambition,” a call for countries to cut more climate pollution than they had committed to cut under the Paris pact.

The Paris rules “may be more important as a durable foundation for country engagement that raises ambition,” Elliot Diringer, executive vice president of the Center for Climate and Energy Solutions, told Bloomberg Environment Dec. 14. “A decision with the title ‘rulebook’ that is too light on details—it won’t be a good outcome.”

The Poland conference is known as the 24th Conference of the Parties to the United Nations Framework Convention on Climate Change, or COP24.

The annual climate conference will be held in Chile in 2019.