As a result, the international community, academics and conservationists have cautiously welcomed a joint declaration at the Cop26 summit in Glasgow this week, which will aim to accelerate the countries’ measures to tackle the climate crisis over the next decade.
While China and the US haven’t always seen eye to eye, their connection is regarded as one of the most crucial bilateral relationships in the world, playing a significant role in safeguarding global economic and security interests.
In recent years new strains have been placed on the relationship, with flashpoints including Donald Trump’s instigation of a trade war, international alarm over the Uyghur genocide, treatment of Hong Kong and Taiwan, and mounting US concerns over cyber warfare.
Illustrating the febrile nature of the relationship, this week satellite images revealed scale mock-ups of US warships in China possibly for practice for a future naval clash, amid heightened tensions between the nations.
But following meetings in Glasgow between US climate envoy John Kerry and his Chinese counterpart Xie Zhenhua on Wednesday, the two negotiating teams produced what they called a “roadmap” for greater co-operation on the climate crisis.
Mr Xie told reporters at Cop26 that both countries understood the need to work together because the challenge presented by the worsening climate crisis is an “existential and a severe one”.
There was “more agreement between China and the US than divergence,” he added.
“This is a step we can build on,” Mr Kerry said. “Every step matters right now and we have a long journey ahead of us.”
The statements signalled a major uptick in relations between the countries, coming just days after US president Joe Biden had criticised President Xi for his absence in Glasgow. “It’s a gigantic issue and they’ve walked away,” he said.
The accord came as the UN’s secretary general Antonio Guterres warned the summit’s 1.5C warming goal was “on life support” due to lack of commitments from countries to rein in their emissions.
“I welcome today’s agreement between China and the USA to work together to take more ambitious climate action in this decade,” he said.
“Tackling the climate crisis requires international collaboration and solidarity, and this is an important step in the right direction.”
EU climate policy chief Frans Timmermans said it was “really encouraging to see that those countries that were at odds in so many areas have found common ground on what is the biggest challenge humanity faces today”.
“It certainly helps us here at Cop to come to an agreement,” he added.
Boris Johnson, who had returned to Glasgow on Wednesday to kickstart what he described as the “inadequate” wider negotiations at the summit, also indicated his relief that the UK-hosted summit had provided a setting for the China-US pact to emerge – although it was unclear if he knew the pact was coming as he departed Scotland before it was announced.
The British prime minister said: “I welcome the strong show of commitment from China and the US last night to step up climate action this decade and keep 1.5C in reach.”
“This is a boost to negotiations as we go into the final days of Cop26 and continue working to deliver an ambitious outcome for the planet.”
Given the increasing level of sabre-rattling between Beijing and Washington in recent months, experts have said the new commitments are a “striking” development.
Oxford University professor Rosemary Foot, an expert on the US and China’s relationship, told The Independent it was “quite surprising” the deal was announced given the countries’ “overall deterioration in relations”.
She added: "Both sides are trying to give some substance to the idea that their relationship can be both competitive and co-operative. Paris in 2015 was the setting for something similar, but ties are far colder and more complex now."
Professor Amelia Hadfield, the head of politics at the University of Surrey, said the new announcement could be a sign of a greater intention to improve bilateral relations between China and the US.
She said: “The USA and China agreement is striking in that it pushes back against the recent narrative which has built up around great power politics. Over the last few years, it has been felt that the USA has become more confrontational with China, with the recent AUKUS pact a key example of the security and defence challenges facing the Indo-Pacific region.
“Yet, the climate change announcement has shown that we should not expect Cold War-style politics either. Instead, China and the USA can work together on matters, which will require their joint leadership and integration of their respective economies in the global economy.”
Durwood Zaelke, president of the Institute for Governance and Sustainable Development, said the pact was “the breakthrough that should set the tone for wrapping an ambitious Cop”.
Campaigners also welcomed the unanticipated pact, suggesting it could help rebuild the momentum which led to the original Paris deal, in which both Mr Kerry and Mr Xie played a significant role.
The WWF’s Manuel Pulgar-Vidal said: “The unexpected joint statement by the world’s two largest emitters, the US and China, saying they will work together to enhance climate action, reflects a heightened sense of the climate crisis facing us.
“This announcement could be a much-needed political signal that the two largest emitters, responsible for more than 40 per cent of global greenhouse gas emissions, are joining forces to prevent a climate catastrophe. It could mirror their efforts before the Paris Agreement was finalised. Back then, they set up the momentum that eventually led to the agreement of the landmark climate accord.”
Greenpeace International executive director Jennifer Morgan said: “It’s always welcome news when the world’s two biggest emitters co-operate on climate change, and a reset of their relationship on this crucial issue is overdue.
“The climate crisis will only be solved if the US and China move toward the same goal of bringing emissions down in line with a 1.5C trajectory as a matter of urgency.”
The two countries said the pact committed them to a working group for this decade, in which they will “meet regularly” and focus on “concrete actions”.
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