Image source, EPAImage caption, Protesters around the globe have been demanding firmer commitments from world leaders on climate change
Activists and politicians have cautiously welcomed an unexpected US-China declaration vowing to boost climate cooperation in the next decade.
The EU and UN described the move as encouraging and an important step, but Greenpeace said both countries needed to show more commitment.
The US and China are the world's two biggest CO2 emitters.
They said they would work together to achieve the 1.5C temperature goal set out in the 2015 Paris Agreement.
The announcement by the two global rivals was made on Wednesday at the ongoing COP26 climate summit in Glasgow. US President Joe Biden and his Chinese counterpart Xi Jinping are now expected to hold a virtual meeting as early as next week.
Scientists say that limiting global temperature rises to 1.5C will help humanity avoid the worst climate impacts. This is compared with pre-industrial temperatures.
In 2015, world leaders pledged in Paris to try to keep the world from warming by more than between 1.5C to 2C through sweeping emissions cuts.
- Read more about the COP26 summit here
- Simple guide to climate change
Reacting to the US-China declaration, Genevieve Maricle, director of US climate policy action at pressure group WWF, said: "This announcement comes at a critical moment at COP26 and offers new hope that, with the support and backing of two of the world's most critical voices, we may be able to limit climate change to 1.5 degrees.
"But we must also be clear eyed about what is still required if the two countries are to deliver the emission reductions necessary in the next nine years. 1.5C-alignment will require a whole-of-economy response."
Greenpeace International Executive Director Jennifer Morgan also welcomed the declaration, but warned that both countries needed to show greater commitment to reaching climate goals.
UN Secretary General Antonio Guterres said the announcement was "an important step in the right direction".
EU climate policy chief Frans Timmermans said it was "really encouraging" to see China and the US working together.
"It shows also that the US and China know this subject transcends other issues. And it certainly helps us here at COP to come to an agreement", he added.
Meanwhile Kevin Rudd, former Australian prime minister and now president of the Asia Society, which works on global climate change agreements, told the BBC that the agreement was "not a gamechanger" but still a big step forward.
"The current state of geopolitics between China and the United States is… awful, so the fact that you can extract this climate-specific collaboration agreement between Washington and Beijing right now is an important piece of momentum," he said.
The US-China declaration calls for increased efforts to close the "significant gap" that remains to achieve that 1.5C target.
There were steps agreed on a range of issues including methane emissions, the transition to clean energy and de-carbonisation.
China's top climate negotiator Xie Zhenhua told reporters that on climate change "there is more agreement between China and US than divergence".
China refused to join an agreement earlier this week to limit methane – a harmful greenhouse gas, but has instead pledged to develop a "national plan" to address the issue.
Image source, ReutersImage caption, China's chief climate negotiator Xie Zhenhua said the US and China had held more than 30 virtual meetings
Mr Xie was followed by John Kerry, the US climate envoy, who said that while US and China had many differences, co-operation on climate was vital.
"Every step matters right now and we have a long journey ahead of us," he said.
China is the world's largest emitter of carbon dioxide, followed by the US. In September Mr Xi announced that China would aim for carbon neutrality by 2060, with a plan to hit peak emissions before 2030.
The US is aiming for net-zero by 2050.
In other developments at the COP26 climate summit on Wednesday:
- A draft of a final COP26 deal was announced, with countries being urged to strengthen carbon-cutting targets by the end of 2022. The document also urges more help for vulnerable nations – but the text has been criticised by many for not being ambitious enough
- UK Prime Minister Boris Johnson urged other national leaders to give their negotiators more leverage to reach a final deal. Speaking at a news conference, he insisted the ambition of keeping global temperature rises below 1.5C was not yet dead
- The sentiment was echoed by COP26 President Alok Sharma, who said, "We all know what is at stake in these negotiations and indeed the urgency of our task." He also suggested "near-final texts" on an agreement could be published overnight before groups convene again tomorrow ahead of the intended final day of the conference on Friday
- The focus of COP26 on Wednesday was travel. Dozens of countries have promised to phase out petrol and diesel-powered cars but the US, China and Germany haven't signed up. A number of major manufacturers – including Ford and Mercedes – have pledged commitments too.
COP26 climate summit – The basics
- Climate change is one of the world's most pressing problems. Governments must promise more ambitious cuts in warming gases if we are to prevent greater global temperature rises.
- The summit in Glasgow is where change could happen. You need to watch for the promises made by the world's biggest polluters, like the US and China, and whether poorer countries are getting the support they need.
- All our lives will change. Decisions made here could impact our jobs, how we heat our homes, what we eat and how we travel.
What will climate change look like for you?
Will the UK meet its climate targets?
How extreme weather is linked to climate change
What is COP26?
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