It seemed apt that Boris Johnson’s first official outing in Rome as dawn broke was at the Colosseum.

It was a perfect setting for a prime minister with a love of ancient history who likes to speak in Latin. And what better backdrop to talk about the challenge of climate change than a gladiatorial ring?

When it comes to landing concrete plans to limit global warming by the middle of this century and avert climate change catastrophe, this PM and host of the critical Glasgow climate summit is fighting a losing battle.

Please use Chrome browser for a more accessible video player

As world leaders gather in Rome for the G20 summit of industrialised nations that leads straight into the COP26 global climate summit, momentum is stuttering in what was already a hugely difficult task. That is to get countries to outline concrete plans – nationally determined contributions – not only to deliver on the 2015 Paris Accord to limit global warming to below 2 degrees Celsius above pre-industrial levels, but also to keep the goal of 1.5 degrees alive in order to save some of the world’s coral reefs and avert catastrophe for small island states and coastal cities threatened by rising sea levels: as one UK government official pointed out to me, Fiji is already buying up land on adjacent islands.

So much at stake and yet world leaders are struggling to keep on track to deliver success over the coming two weeks. China and India, the world’s first and third largest greenhouse gas emitters in 2019 – between them accounting for over a third of emissions with Beijing by far taking the lion’s share – have refused to commit to reaching net zero by 2050, while China has pushed the peak of its greenhouse emissions back to 2030.

And while the US, the world’s second biggest polluter, has committed to net zero, President Biden has come to Rome without an agreement of his plan with Congress.

And if you wonder how critical China is, here is the context: the UK is responsible for 1% of global emissions, against 27% for China in 2019. Mr Johnson can bring the UK to the table, but without China the hopes of “keeping 1.5C alive” look hopeless.

Queen on ‘very good form’ and country ‘wishes her well’, says Boris Johnson – after doctors advised monarch to rest

COP26: Boris Johnson warns of ‘very difficult’ climate change fight but says ‘whole of humanity is in the ring’

COP26: Boris Johnson invokes fall of the Roman Empire as he warns world faces uphill battle in climate fight

And when I asked the prime minister if he’s fighting a losing battle against the backdrop of that gladiatorial ring, he admitted things were “very difficult” as he – without naming names – called out “political indifference”.

He said: “The whole of humanity, is in the ring. And the foes of humanity are apathy and political indifference and lack of will and people’s excessive caution about what they can achieve. Those are the foes that we all collectively face. And actually, I think that we can still do it. I think there is a chance, if everybody puts their minds to it, that we can get an agreement that will allow us to restrain the growth in temperatures.”

Please use Chrome browser for a more accessible video player

The PM said he still believed – despite failing to get China to sign up to more ambitious targets and no national plan (yet) from President Modi of India – that there was a six in ten chance that COP26 will be a success, as he begins four days of intense diplomacy.

There is private acknowledgement within government that China will go at its own pace and follow its own interests (such as increasing use of coal in the short-term to avert energy supply shortages).

But that President Modi – India emitted 6.3% of all global emissions in 2019 – has agreed to attend the summit is cause for optimism. New commitments from the world’s third biggest greenhouse gases emitter, could give COP26 fresh momentum.

Mr Johnson told me he wanted to see “more progress from lots of countries” and said he impressed upon President Xi in a phone call on Friday the need to move away from coal.

Please use Chrome browser for a more accessible video player

“I said to President Xi is that it is possible to move away faster from coal than China is currently doing. The UK did it. I told President Xi, when I first went to Beijing as Mayor of London we had 40% of our energy came from coal. It is now less than 1%,” he said.

But in a world where those committed to tackling climate change – the UK, the US, the European Union and allies such as France and Germany – the tensions around Brexit threaten, once more, to overshadow this summit as they did at the G7 in Cornwall.

Back then the PM and President Macron had a very public row over the post-Brexit arrangements for trade between Great Britain and Northern Ireland – ‘sausage wars’ as it become known.

Please use Chrome browser for a more accessible video player

At this summit it is fish that are causing serious problems with France and the UK locked in a bitter row over post-Brexit fishing rights.

It is not the backdrop the prime minister would perhaps want to this summit, but he was ready to fan the flames of this escalating trade row in our interview on Saturday morning as he refused to rule out triggering the dispute resolution mechanism as early as next week with the EU to impose sanctions on Paris.

He told me that he was “worried” there might be a breach of the Brexit trade and cooperation agreement, struck last Christmas eve, and that he would not rule out escalating the issue next week.

For him, the row with France over fish is “frankly small beer or trivial by comparison to the threat to humanity.”

Subscribe to ClimateCast on Spotify, Apple Podcasts, or Spreaker.

But for Emmanuel Macron, the disputes over fishing rights and Northern Ireland are more than this, it is a “test of [the British government’s] credibility” in the eyes of the world.

“When you spend years negotiating a treaty and then a few months later you do the opposite of what was decided on the aspects that suit you the least, it is not a big sign of your credibility,” Mr Macron told the Financial Times in an interview on the eve of the Rome summit.

Mr Johnson knows that dealing with climate change can only be done as “team world” with the biggest, most industrialised nations pulling their weight.

But Brexit and its fallout again threatens to overshadow the summit, and that doesn’t just matter for Anglo-Franco relations, it matters for the entire world.

Watch the Daily Climate Show at 6.30pm Monday to Friday on Sky News, the Sky News website and app, on YouTube and Twitter.

The show investigates how global warming is changing our landscape and highlights solutions to the crisis.

Related posts:

PM warns people not to meet friends and family indoors – even if they’ve had COVID jab Labour leader Starmer criticised by his own party for visit to church with homophobic links Labour demands new law on political lobbying after controversy over Cameron’s Greensill links Starmer says he takes ‘full responsibility’ for Hartlepool by-election defeat Climate minister under fire for jetting to 30 countries – including several on red list PM not expecting to isolate after member of his staff tests positive for COVID Minister says he’d be ‘surprised’ if there weren’t any drug users in Houses of Parliament PM: ‘Complete nonsense’ to say govt prioritised animals over people during Afghan evacuation PM minded to move to Plan B of COVID rules this week, Sky News understands ‘Furious’ PM apologises over footage of No 10 staff joking about ‘Christmas party’ Labour say PM’s position ‘completely untenable’ as he prepares for questions over lockdown party PM cancels visit after family member tests positive for COVID