Today is likely to be a slow day, in news terms.

The negotiations themselves happen behind closed doors but there are lots of journalists and observers keen to hear the latest.

A briefing currently underway here, featuring a panel of scientists giving their views on the latest draft, is absolutely packed.

People are sitting in the aisles and - now - being turned away at the door by security staff.

The UNFCCC tweeted this video of reporters waiting to catch the latest outside one of the plenary halls.

David Shukman
Science editor, BBC News

A quick wander around the delegation offices reveals that many still have not opened for this key day; the negotiators must be sleeping after another session of late-night talks.

The shape of a deal is becoming clearer but some of the toughest issues remain.

Does it have the makings of an historic agreement to shift the course of the global economy onto a low-carbon pathway?

Yes, says Lord Stern, the author of a landmark report into the economics of climate change.

No, says Prof Kevin Anderson of Manchester University – too many of the key measures have been stripped out.

He highlights the absence from the text of aviation and shipping, two fast growing industries that produce greenhouse gases equivalent to the UK and Germany combined.

Whatever emerges, multiple interpretations are inevitable. And the final details are still in play.

Miguel Arias Canete, EU climate commissioner, tweeted this morning:

Roger Harrabin
BBC environment analyst

How strong is this latest draft? And can it stick? Opinions differ.

I’m told by a senior source that Chinese delegates in small group meetings are firmly opposing measures in the text to nod towards a maximum temperature rise of 1.5C.

They are also opposing the plan for the world to become “emissions neutral” in the second half of the century.

My source says Saudi Arabia is making the same points but much more aggressively, threatening small island states that if they win their 1.5C wording, Saudi will ensure that all other references in the text to special help for vulnerable nations will be removed.

I can’t verify this yet – but the source is good.

There’s also pressure to strengthen the document as well as weaken it. Some observers here think the wording about emissions neutrality is too vague.

Lord Stern, author of the influential Stern Review on climate economics, told me the contentious phrase "emissions neutrality" was in fact very clear: Whatever greenhouse gases you emit, you neutralise by forests, or restoring degraded land to store carbon, or by carbon capture and storage.

But this may be premature – there’s still a long way to go in negotiations.

The current draft text agreement says that global temperature rise should be held below 2C - with the ultimate target set at 1.5C.  

Prof Sir Brian Hoskins - who is a meteorologist and climatologist from Imperial College London - tackles this issue on the BBC's Victoria Derbyshire show and explains that although 1.5C is in the draft text, he believes it is an "aspiration".

"People are saying even two degrees is not going to be easy for everyone, so if we could make it 1.5C that would be great.

"The aspiration is there and I welcome that."

Sir Brian said that 1.5C is only "achievable" if we start now. 

"If we say well this is difficult let's leave it five or ten years then come back and reassess... then one-and-a-half degrees would be way out of reach and probably so would two degrees."

The "sticking points" mentioned earlier by the WRI's Jennifer Morgan are the same three that the conference president highlighted when he released Wednesday's draft - and we've had another version since then.

Indeed, before COP21 started, many would have expected these issues to come to the fore in the summit's endgame.

Here's our science reporter Jonathan Webb explaining them yesterday:

Jennifer Morgan - global director of the Climate Program at theWorld Resources Institute, external- told BBC News: "I'm still cautiously optimistic. They negotiated overnight - they made progress.

"But every country just has to go further. They have to reach to the extreme of what they can do here - it's all still within reach."

She said there were three "sticking points". They were:

+ Developed countries need to come forward with something that is fair, and that shows they are going to differentiate, and have developed countries do more.

+They need to come together around a clear long term goal - that will shift investments into clean energy

+And they need to have a solidarity package for the poorest countries to help them deal with the impact of climate change.

The BBC's environment analyst Roger Harrabin has been speaking with the chairman of the Grantham Research Institute on Climate Change and the Environment, external, Lord Stern, about greenhouse gas neutrality.

If you're just joining us and you want a quick recap on what is going on, here are a few easy-to-read pointers:

COP 21 - the 21st session of the Conference of the Parties - is seeing more than 190 nations gather in Paris to discuss a possible new global agreement on climate change, aimed at reducing greenhouse gas emissions to avoid the threat of dangerous warming due to human activities.

Explained: What is climate change?

In video: Why does the Paris conference matter?

Analysis: Latest from BBC environment correspondent Matt McGrath

Negotiators at the Paris climate summit aim to wrap up a global agreement to curb global warming on Saturday - a day later than expected, the hosts France have confirmed.

But nonetheless today is set to be a crucial day in terms of reaching an agreement, as drafts texts continue to be whittled down and a firm agreement edges nearer.

Any deal signed in Paris would come into being in 2020.

Read more here.

This evening's text, which observers expect to be followed by at least one more version, is not due until 21:00 local time (20:00 GMT) at the earliest.

With a very big day ahead on Friday, we are closing the BBC's live page for today.

Come back tomorrow for reactions to the text - and to track developments.

Our coverage will recommence at about 11:00 GMT tomorrow, Friday 11 December.

Will the French hosts' impressive diplomacy and organisation see them meet their Friday evening deadline - or will COP21 follow in the sleepless footsteps of past COPs, long into the weekend?

Whenever it ends, this summit has been notable for a strong, shared determination to see an agreement signed.

We will soon find out what sort of agreement it is.

The so-called "high ambition coalition", a group of countries pushing for tough goals and regular re-assessment in the agreement, continues to add members.

This tweet comes from the foreign minister of the Marshall Islands:

Read environment correspondent Matt McGrath's news story about this alliance:

US joins climate 'ambition coalition'

Roger Harrabin
BBC environment analyst

Much of the pressure for a tough deal at the Paris climate conference has come from coral island states whose governments fear inundation - but the climate chief of the Red Cross/Red Crescent has urged nations not to make climate change worse by maltreating their local environment.

Speaking to me before COP21, Maarten van Aalst said people in many coral states were increasing their own vulnerability by damaging reefs and beaches that protect their homes.

He said reefs were being wrecked by people using dynamite to fish, by pollution, by over-fishing – and sometimes even by people smashing them up for building materials. On many islands, he said, people had taken sand from the beach to raise the height of their homes – but in the process removed the protective shield of the beach to temper the waves.

In drylands of East Africa, Mr van Aalst said populations were too high for the land to support, so they were over-grazed. In other countries trees had been cut down, which encouraged flooding.

Climate change is a huge problem, he said. But people should stop making it worse.

Mr van Aalst was interviewed for my Changing Climate documentary on BBC Radio 4. His comments were aired today on PM.

Delegates walking through the conference this morning were greeted by recorded messages in multiple languages.

Campaign group Avaaz organised the "audio installation" to accompany its petition of 3.6 million names calling for climate action.

Image source, Avaaz

At the front entrance, protesters from Oxfam were camped out in "big heads" representing world leaders.

Image source, EPA

At a lunchtime press conference today, China's Gao Feng was one of several negotiators who spoke to journalists about the previous draft - which has been the subject of tough negotiations today and last night.

He said that "maybe a little longer than 48 hours" of the "most difficult" negotiations still lay ahead.

The "Comité" (see previous post) will now gather at 21:00 Paris time (20:00 GMT), screens around the conference venue have announced.

It is unclear whether the draft text will be released after that meeting, or before it.

The "Comité de Paris", COP21 president Laurent Fabius's initiative for bringing delegations together for a status report, is tentatively scheduled to meet in an hour's time.

A new draft text should be released soon after that - and another long night of negotiations almost certainly lies ahead.

La Seine, one of the site's huge plenary halls, is set aside for this committee gathering, but plenty of other rooms are timetabled for delegates to watch the proceedings...

David Shukman
Science editor, BBC News

The Paris talks have gone private, so keeping track of them has become almost impossible.

Ministers and their negotiators are shuttling between meetings. We catch the odd glimpse of fast-moving posses.

In one corridor I spotted India’s environment minister, surrounded by officials, all of them speaking loudly, but they turned through a door before I could grab a picture. John Kerry has just shot past, someone told me.

The delay in the release of the latest draft is yet another sign that the process is now cutting to the bone of each delegation’s positions. The chatter is about red lines.

And one theme keeps emerging: the challenge of dealing with a rapidly changing world.

For the richest of the countries still classified as ‘developing’ – Singapore is mentioned – the fear is being forced into becoming donors to the most vulnerable nations.

For the poorest nations, the worry is that the agreement will be so riddled with compromises that it will end up virtually meaningless.

For the UK, the voluntary carbon reduction plans will only deliver the cuts needed if they are reviewed and strengthened every five years – others want that put off till 2030.

And everyone is talking of another long night.

The chief United Nations environment officer is still optimistic that a deal will be hammered out soon, the AP news agency reports.

"We're now down to some of the so-called red line issues, some of the defining issues in the convention that have to do with principles," said Achim Steiner, United Nations Environment Program director. 

"I think the fact that we are now essentially left with maybe three or four issues that need to have a political compromise negotiated and formulated should give us courage and hope that we are actually moving to an agreement."

Steiner said he thinks the final issue will be differentiation between rich and poor nations, calling it "one of the defining principles of where the convention began its journey".

Steiner said he is still hoping to end talks Friday night as the French have promised.