I saw firsthand how hard France worked to make the Paris Agreement happen – the UK must do the same at Cop26

Avoiding the worst impacts of the climate crisis is important enough. But that isn’t the only reason why the Glasgow summit matters to the UK

Take it from me, climate diplomacy is not easy and there is a lot at stake. Leading the UK delegation at the 2015 UN climate talks in Paris, I saw firsthand the profound efforts of the French hosts – before and during the summit – that culminated in the historic Paris Agreement.

Taking on the role as hosts of the next climate summit, Cop26 in Glasgow, the UK assumes a position of considerable trust. Avoiding the worst impacts of the climate crisis is important enough, as a goal of climate diplomacy. But that isn’t the only reason it matters to the UK.

Glasgow marks the point that world leaders must commit to greater climate ambition, to keep the Paris Agreement’s goal of halting warming at 1.5C within reach. How we steward these talks will be subject to intense scrutiny, and will define international perceptions of the UK for years to come.

Success at Cop climate summits is by no means assured. The last meeting in Madrid fell short, and the 2009 Copenhagen summit spectacularly failed to live up to expectations. The winds are favourable for Glasgow – we could not have imagined back in 2015 just how far we would have come. Global geopolitics are going with the grain of climate action, technologies have come on in leaps and bounds as costs have fallen, and many of the world’s biggest companies are committed to transformative change.

But this is not enough. Success still requires diplomatic heavy lifting between now and November. Whilst that is undoubtedly already underway, this week’s leaders’ summit on climate convened by the US will fire the starting pistol on the race in earnest.

The US, under President Obama, helped drive success in Paris and, after five years of climate inaction under Trump, Joe Biden campaigned and won on the most ambitious climate agenda in US history. As we anticipate a bold new US pledge ahead of the summit, it would be hard to overstate the significance of the return of the US to global climate leadership.

Bringing big emitting, leading and climate vulnerable nations together on Earth Day, President Biden will be balancing some difficult tensions between attendees, including China’s Xi Jinping, Brazil’s Jair Bolsanaro, and Russia’s Vladmir Putin. Leveraging that enhanced US climate action commitment though, we can hope to see movement from others such as Canada, Japan and South Korea.

But also on the agenda is support for poorer nations. They simply cannot afford to pick up the bill for the climate crisis - which is damaging their agriculture and infrastructure. Nor can they afford to take the necessary steps to cut their own emissions. This is all compounded by spiralling debt in fragile economies that have crashed during Covid. Six years before Paris, richer countries committed to giving $100bn £71.8bn) a year in climate finance by 2020. Well into 2021, that has not been delivered; the trust of poorer nations will be lost if it is not delivered soon. There won’t be an agreement in Glasgow without this trust, making finance critical in the negotiations.

The US summit will not resolve everything; nor will each of the other important 2021 gatherings, including the G7 and G20. But leaders must work hard to build momentum towards and, crucially, beyond the Cop in Glasgow.

That is, first and foremost, the job of the Cop host. Former prime minister of France, Laurent Fabius – with the considerable weight of the French foreign ministry behind him – was a force of nature, mobilising the power of his role to achieve the Paris Agreement.

I very much hope that the UK has learned from this. Alok Sharma is working hard as Cop president designate and I was glad to see his role made full-time as I suggested last year. But he needs his senior ministerial colleagues to bring to bear the formidable weight of the UK’s civil and diplomatic services to the task. Chancellor Rishi Sunak has a critical role working with his peers in wealthy nations to resolve access to finance and debt relief for less developed countries, as well as at home to deliver the investment needed to realise the UK’s hugely welcome and world-leading recent climate pledges.

And, although a leader on climate finance, let’s be honest that the UK’s job is made harder by the government’s decision to cut its overseas development aid last year. This undermines UK authority – both in pressing donor countries to loosen their purse strings, and with developing countries who see funds cut off just as they most need them.

The UK parliament has a role here to support that global scrutiny. The vast majority of people in the UK understand the urgency to act on climate and will expect their MPs to hold the government to account on missteps like the aid decision. All senior ministers will have to face the house to explain their role in making this critical summit, the biggest ever hosted by the UK, a success.

Ultimately, success at Cop26 will be defined, as it was in Paris, by those who are most ambitious. By definition, that means those with most at stake – the world’s most vulnerable countries, who contribute least to the problem, but bear the brunt of impacts and costs.

The UK can succeed, and having the US back makes a big difference. But success is far from in the bag. That is ultimately why Sharma needs the prime minister, foreign secretary and chancellor to join him in bringing their A-game if the UK is to walk away from the Glasgow Cop with its head held high.

Amber Rudd is a former secretary of state for energy and climate change. She was also the UK lead at Cop21