America’s special envoy on climate change John Kerry has told Sky News that strained relations between the US and China have made it harder for him to do his job.

Speaking exclusively to Sky from a climate summit in Milan, Mr Kerry said his ability to persuade China to be more ambitious in reducing its carbon emissions has been affected by the growing geo-political tensions between the two superpowers.

He said: “It’s been more complicated because of other issues.

“Originally… climate was going to be treated on its own, because of its urgent demands.

“But reality has crept in, in the last few months, and so there’s been a slowdown in our ability to be able to move.

“My hope is that we will still be able to find some common ground.

“I will be meeting with my counterpart from China shortly, and we are both hopeful that we can make some progress.”

Mr Kerry has previously said that if China fails to shift its net zero carbon emissions target from 2060 to 2050, then the rest of the world’s efforts to tackle global warming could be in vain.

I ask him what message it will send to the rest of the world if China’s President Xi Jinping does not turn up to COP26 in Glasgow in person.

He says: “I actually haven’t really thought about it very much to be truthful.

“Some 190 some countries will come… and it’s not going to be defined by if President Xi shows up.

“The vast, vast majority of countries in the world are very anxious to be part of a moment where we really turn a corner, and we’re heading in the right direction of the climate crisis.”

And what is his assessment of host of COP26 and UK Prime Minister Boris Johnson, who in a recent speech flippantly and jokingly referred to combating climate change as a “politically correct green act of bunny hugging”?

Does special envoy Kerry fully trust that he is the right person to help lead the global fight against the climate crisis?

He said: “Well, the proof is in the pudding, right?

“I think this is not a matter of trust in the sense that we’re making judgements about whether we trust this or trust that.

“He’s committed to this, and he’s publicly doing major things in order to try to make this work.

“And I’ve been impressed by the statements he’s made to date, committing his government and the world to take action, and I think he’s offering leadership.

“But in the end you know we have to get there, and it’s the doing the actions… that’s what will determine, what should determine, the judgements people will make about Glasgow and what happens there.”

I ask the former US secretary of state if he ever feels anger towards those nations and leaders who are not willing to act.

He says: “I feel frustration in the length of time and the slowness with which, as a world, we have been moving to date.

“People have been put in jeopardy by current practices, and for the last 30 years, we have known how bad it is and still, people are moving too slowly.

“You know I’m not going to get lost and try to just voice anger, I’m going to try day to day to do my best, which is what I’m doing.

“I consider myself lucky to be able to be in the middle of that fight.

He pauses and adds, slightly jokingly, “Sometimes I can reserve the anger and scream in the dark, but I couldn’t do it publicly.”

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

I ask if he views COP26 as an opportunity for redemption for a generation that failed to tackle the climate crisis.

He almost bristles.

“I haven’t thought about it that way, no.

“We were a generation that marched for civil rights and for human rights, for the environment, for women’s rights, and we made a difference.

“So, you know, I’m not here to apologise.

“I’m here to fight for the next step.”

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.