Three main issues are proving hard to crack in the urgent quest for a climate change agreement:
A key demand is to ramp up financing from 2020 and to clearly spell out where the money will come from. The climate draft text still has different options on post-2020 financing, with US$100 billion (S$140 billion) suggested as a floor.
While poorer states want the rich to pledge more cash, rich nations want wealthy developing countries to pledge more as well, broadening the financing pool to reflect rising emissions from the developing world.
SETTING THE 'RED LINE'
The Paris draft text seeks to place a limit on global temperature rise, with wording of keeping warming "below 1.5 deg C above pre-industrial levels" the most ambitious and favoured especially by small island states already affected by rising seas.
Why is the temperature goal important? The world has already warmed about 1 deg C by this year, according to the UN's weather agency. This extra heat in the atmosphere and oceans is creating stronger storms, more intense rainfall and changing weather patterns, triggering heatwaves and droughts. As temperatures rise, these extreme weather swings are expected to get worse, affecting everyone.
Vulnerable countries say that wording of keeping warming to below 2 deg C - currently an option in the text - is too risky and would condemn their nations to an uncertain future.
REVIEWING ACTION PLANS
Most countries have submitted climate action plans. But how to vet and scale these up regularly and fairly? The text has options to review climate plans every five years, which most countries seem to back. This is important because the current climate plans are too weak and put the world on a path to warm by at least 2.7 deg C or more.
Regular reviews and ramping up emission cuts are crucial if the world is to quickly cut carbon pollution blamed for heating up the planet. But the planned review system has run into trouble because poorer nations want wealthier states to take the lead and take on more onerous reporting and verification rules, with easier requirements for poorer states.