Jonathan Webb
Science reporter, BBC News

In multiple small meetings around the sprawling Le Bourget conference site, delegates are debating a draft.

It was released yesterday evening, before the second night in a row of all-night negotiations.

As a reminder, the present document has about 50 square brackets left in it; these indicate places where countries still need to choose between alternative wording.

The draft that landed one day earlier, on Wednesday evening, was still strewn with around 300 brackets; the version before that - released on Saturday - was plagued by more than 900.

Conference president Laurent Fabius, spoken of in almost glowing terms by a wide range of participants and observers here, has promised a final draft at 08:00 GMT tomorrow morning - presumably with no brackets in it at all:

Whether or not this revised deadline is met, the overriding feeling here this week has been that COP21 will indeed produce a deal.

And perhaps the most tangible measure of this momentum is the surprisingly rapid pruning of punctuation.

Brazil's arrival in the "high-ambition coalition" was hailed as a game-changer by other members of the coalition, like the EU, as well as some NGOs like Greanpeace.

But the announcement prompted a rebuke from the Chinese delegation.

Following the press conference, Chinese negotiator Gao Feng told BBC Chinese that China "is not informed about the group" and has never been invited to join.

Mr. Gao said: 

David Shukman
Science editor, BBC News

After being rebuffed by the Saudis in my bid for an interview with them (see earlier post), I have had far better luck with the Chinese.

That marks a staggering shift from China’s attitude to the media back at the Copenhagen summit in 2009. In that chaotic gathering I never got near a spokesperson for China and China itself was blamed by many for blocking any chance of a deal.

This time, we wander over to the Chinese pavilion and meet the smiling figure of Gao Feng, who is no less than the Chinese Foreign Ministry’s special representative on climate change.

We talk about China’s insistence that the distinction is maintained between developing and developed countries.

He then says that China has agreed to reduce its emissions of greenhouse gases. I gently point out that those emissions are set to rise for at least the next 15 years.

Mr Gao hits back by saying that China is leading the push for renewables.

The exchange is fascinating. What a change.

Responding to Brazil’s announcement that it is joining the High Ambition Coalition, Martin Kaiser, head of international climate politics at Greenpeace, said: “This move by Brazil could change the whole dynamic in the last closing hours of this conference.

“We welcome that the High Ambition Coalition is championing the issues which are critical to the agreement - a temperature limit of 1.5C, a strong long-term goal of decarbonisation, five-year cycles for reviewing climate actions and clear transparency rules.

“Missing from the coalition were any of the major emerging economies.  With this move, Brazil can become a bridge builder to the others."   

President Obama spoke to his Chinese counterpart Xi Jinping by phone on Friday with both leaders saying they are committed to an "ambitious" deal. 

The US president has certainly been keeping the phone lines busy as he's also spoken to India's Prime Minister Narendra Modi, French President Hollande and Brazil's Dilma Rouseff this week. 

"Both leaders agreed that the Paris conference presents a crucial opportunity to galvanize global efforts to meet the climate change challenge," a White House statement said.

"They committed that their negotiating teams in Paris would continue to work closely together and with others to realize the vision of an ambitious climate agreement."

It is particularly significant to see Brazil join ranks with the "high-ambition coalition" because in talks like these, the huge South American power is a member of the BASIC group of large and rapidly developing economies (the others being India, China and South Africa).

This group has tended to see continued development as a more critical issue than reducing emissions.

Miguel Arias Canete, EU climate change chief, tweeted:

The "High Ambition Coalition" here at the COP21 climate summit has now been joined by Brazil.

This alliance took shape a little earlier this week, initially launched by the EU and 79 other parties including many developing nations - and joined by the US and others on Wednesday.

These countries want a tough overall goal, mentioning a temperature-rise limit of 1.5C in the agreement text, and a strict system for assessing whether countries stick to - and increase - their pledges.

Speaking to a huddle of journalists outside his delegation's office a little earlier, one of China's negotiators Gao Feng made it clear that demarcating rich and poor countries was still the biggest issue for his team:

Asked where the push-back was coming from, Mr Gao named wealthy countries like the US, the EU, Japan, Australia and New Zealand.

Last night's talks were tense and difficult, Mr Gao said, adding that the current text is not "the kind of language" his team wants to take home.

In front of the flag-emblazoned pillars at the site entrance, the message of the day was "Adieu fossil fuels".

The message, organised by campaign group Avaaz, was delivered in capital letters by a group of children.

Image source, Avaaz

Meanwhile, a procession of activists got out their hardhats and rope in the Climate Generations exhibition zone.

They were calling attention to "Mountain Day" here at COP21 - highlighting the sensitivity of mountainous regions to climate change.

Rebecca Morelle
Science correspondent, BBC News

Paul Bledsoe, former White House climate advisor under Bill Clinton, said he thought that "verification" and "transparency" almost certainly would have been discussed in the phone call between President Obama and China's Leader Xi Jinping.

Essentially this is the issue of tracking whether a country is doing what it says it is doing when it comes to its emissions.

This though - Mr Bledsoe says - means opening up your books, something that he says until now China has been very reluctant to do.

The Chinese news agency Xinhua reports that President Xi Jinping and his US counterpart Barack Obama held a telephone conversation this morning "to exchange views on the Paris climate conference, China-US relations and other major international issues of common concern".

As discussions continue in Paris, Obama reportedly said the US was willing to "maintain close coordination with China" to promote success at the climate conference. 

Xi said that his and Obama's cooperation to date had "sent a positive signal to the international community" and that as negotiations conclude, China and the United States "need to strengthen coordination and work together with all parties" to drive home a satisfactory agreement.

Image source, AP

Scientists at the very busy briefing we mentioned earlier expressed concern about the draft agreement that was released last night.

Kevin Anderson from the Tyndall Centre for Climate Change in the UK said it was even weaker than the document that emerged from Copenhagen - the notorious 2009 round of these talks, which still haunts proceedings.

Prof Anderson said:

Steffen Kallbekken, director of Norway's Centre for International Climate and Energy Policy, reiterated that the myriad individual pledges of nations - known as intended nationally determined contributions or INDCs - currently aren't good enough.

Hans Joachim Shellnhuber, founding director of the Potsdam Institute for Climate Impact Research, said:

Joeri Rogelj, a research scholar at the Energy Program of the International Institute for Applied Systems Analysis, in Austria, also wants the text to be stronger - and stricter:

David Shukman
Science editor, BBC News

In almost every discussion about the progress of the talks, one country keeps being mentioned as holding things up: the oil-rich kingdom of Saudi Arabia.

So this morning I headed to the lavish pavilion of the Gulf Cooperation Council to ask for an interview. Impressively large screens show images of solar panels in the desert.

My reception was very friendly and polite. But I have just heard by email that “we cannot arrange for media interviews right now”.

In a long statement, a spokesperson suggests support for action on climate change but only up to a point. Any attempt to meet a global temperature target must “allow ecosystems to adapt naturally to climate change” and “ensure that food production is not threatened”.

The response says that while a 2C target can be met, the goal of limiting warming to 1.5C is not based on “robust information and the support of science”.

And the Saudi statement has another argument against a 1.5C target as well: “…what we want is to avoid a target that puts developing countries at a disadvantage by placing an extra burden on their economies”.

The Saudis have a certain reputation from previous gatherings of this kind for last-minute objections.

What will they do this time? We’ll soon find out, but not in the form of an interview.

Joel Budd, a journalist for The Economist, told BBC News that the goal to limit global temperature to below 2C was "not realistic".

"If we keep emitting greenhouse gases at exactly the rate that we're emitting them at the moment then we have 30 years before we have put enough into the atmosphere to eventually warm the world by two degrees.

"Only 30 years... So it's very, very hard to see how we don't get to two degrees.

"One and a half degrees I think is more than unrealistic - it's verging on the comical."

An activist from Greenpeace suspended himself from the Arc de Triomphe...

...and the police appear to be intervening.

While we wait for more news, brush up on how the countries involved in these negotiations group themselves into powerful blocs - with help from our environment correspondent, here in Paris:

Speaking to the media just after Ban Ki-moon (see previous post), COP21's French chair Laurent Fabius promised a text of the Paris agreement - which he "thinks will be adopted" - by 09:00 Paris time (08:00 GMT) tomorrow morning.

UN Secretary General Ban Ki-moon has just spoken to the media in the last few minutes.

He said: "This negotiation is most complicated, most difficult, but, most important for humanity.

"There are still several outstanding issues like differentiation, ambitions and climate financing etc.

"But during many years of negotiations they have identified all the issues, very good solutions have already been presented. This morning we have a much clearer streamlined text.

"Many brackets have been dropped and there are a few brackets remaining.

"We have very limited hours remaining. I am urging the negotiators to make their decision based on global vision.

"This is not a moment [for] talking about national perspectives."

Paul Bledsoe - former Clinton White House climate adviser - says one of the key issues remains reporting and verification of emissions by individual nations.

Speaking to the BBC in Paris he said:

Mr Bledsoe added that while some common ground has been found on sharing the responsibility for climate change, the US will be "a little disappointed" that a target of reviewing national climate plans every five years will not be mandatory for all countries.