A draft agreement at the COP26 climate summit has watered down commitments to end the use of coal and other fossil fuels, as countries race to reach a deal after two weeks of talks.
While the language around fossil fuels has been softened, the inclusion of the commitment in a final deal would be seen as a landmark moment.
A deal must be agreed by the end of the summit, which is in its final hours.
The UN meeting is seen as crucial for limiting the effects of global warming.
The draft agreement, which was published early on Friday following all-night talks, also asks for much tighter deadlines for governments to reveal their plans to reduce greenhouse gas emissions.
And it also strengthens support for poorer countries fighting climate change.
Negotiations over a final deal could stretch late into Friday, or potentially even longer.
On Friday,UN Chief Antonio Guterres said Cop26 would probably not achieve its aims and the goal of limiting global warming to 1.5C is on “life support”.
Scientists say that limiting warming to 1.5C compared to pre-industrial levels will protect us from the most dangerous impacts of climate change – it is a key part of the Paris agreement that most countries signed up to.
Meeting the goal requires global emissions to be cut by 45% by 2030 and to zero overall by 2050.
One example of the impact of global temperature rise above 2C is the death of virtually all coral reefs, scientists say.
Prof Jim Watson at University College London said the draft agreement had encouraging elements, but that overall it was “nowhere near ambitious enough”.
A previous version of the agreement called upon parties to “accelerate the phasing-out of coal and subsidies for fossil fuels”.
But this has been changed to call for “accelerating the phaseout of unabated coal power and of inefficient subsidies for fossil fuels”.
Unabated coal is coal produced without the use of technology to capture the emitted carbon.
But the draft requests that countries submit their plans – known as nationally determined contributions (NDCs) – to reduce greenhouse gas emissions and adapt to climate change by next year’s climate summit. Previous agreements asked countries to submit these NDCs every five years.
“It could be better, it should be better, and we have one day left to make it a lot, lot better,” says Jennifer Morgan of Greenpeace International.
“The key line on phasing out coal and fossil fuel subsidies has been critically weakened, but it’s still there and needs to be strengthened again before this summit closes.
“But there’s wording in here worth holding on to and the UK presidency needs to fight tooth and nail to keep the most ambitious elements in the deal,” she says.
This latest draft of the decision has gained in strength in many areas – but as in every negotiation, there are some losses too.