Following the tragic events which unfolded in Paris on Friday evening, our thoughts and prayers at the present time are with everyone in Paris, and indeed the whole of France.

With a sharp focus now on security concerns, the French capital will continue to dominate the headlines, as many world leaders finalise their travels plans and head for the French capital later this month for the COP 21 climate talks in Paris.

Now only days away, these COP meetings – an acronym referring to the conference of the parties to the UN Framework Convention on Climate Change, or UNFCCC – take place each year, with the ambition of securing a global deal to address man-made climate change. The ambition for such a deal tends to focus around two main aims; concrete commitments from all nations to deliver meaningful reductions in carbon emissions, both from developing economies as well as developed countries, complemented by finance to assist vulnerable countries in adapting to the impacts of climate change.

Participating in a renewable energy conference in Brussels on Thursday last week, I heard from senior officials at the European Commission, as well as Ambassadors and Permanent Representatives to the EU from France, Germany and the US, who were there to share their hopes and aspirations for COP 21.

The overwhelming mood is one of cautious optimism. It seems lessons have been learned from the fiasco of the Copenhagen COP a few years ago, when expectations were last so high that a global deal was within reach, only to be dashed as the talks broke down amidst recriminations.

As COP chair for the next 12 months, the French team have certainly been very busy laying the ground for a deal.

Last week, four “pre-COP” working groups, tasked with tackling some of the key themes of a deal, were hard at work navigating the possible “landing zones” of an agreement. And this agreement already exists in skeletal form, having been whittled down to a just about manageable 31 pages, albeit littered with square brackets.

Needless to say, the form this agreement will take is set to be crucial, in more ways than one.

First, it’s clear that the scale of ambition when it comes to emission reductions is not yet where it needs to be. One of the requirements of last year’s talks was for all countries to submit their individual commitments, in the form of “Intended Nationally Determined Contributions”, or INDCs. With a few exceptions, these are now in, representing over 90% of global emissions.

However, the broad consensus from the scientific community appears to be that the combination of these efforts will see a global temperature rise confined to between 2.7 to 3 degrees. This is well above the 2% limit after which any beneficial effects of climate change are expected to become outweighed by the downsides (- although some scientists are now telling us that we may already have reached this threshold).

And countries can afford to be more ambitious, since there is increasing evidence that reductions in emissions need not be at the expense of economic growth. The performance of the EU itself is a case in point – since 1990, the EU economy has grown by 46% whilst its greenhouse gas emissions have contracted by 23%, a message that many businesses have already grasped as they adapt their growth strategies to encompass sustainability.

Second, and more so now than ever, negotiators are going to be acutely conscious of how any deal plays politically back home. In particular, with President Obama firmly in legacy mode, all eyes are on the US which, to much fanfare, announced its own carbon reduction commitment last year in an announcement jointly choreographed with China. With its federal system and complex law making processes, it is up for debate whether the US can stomach an agreement with legally binding targets. The gulf between Democrats and Republicans on this topic is huge, and the US administration has a tricky job in navigating any deal past a hostile Senate, never mind ensuring that the deal is sufficiently set in stone that any future Republican President can’t turn his or her back on it once in office.

Under US law, treaties require ratification from two thirds of the Senate, in contrast to so-called executive agreements, which require a two thirds majority approval from both the Senate and the House of Representatives although some may be effective solely on the signature of the President. This is not straightforward, so expect some testy arguments around the extent to which some parts of any agreement may or may not be legally binding, and what it’s actually called.

That said, as one of the Ambassadors reminded us in Brussels last week, regardless of what a deal in Paris might look like, it won’t be the end of the matter, just the start of the final sprint.

Andrew Whitehead is Senior Partner at law firm Shakespeare Martineau and leads the firm’s Energy & Climate Change practice.