"We showed up," says President Biden as he calls out President Xi Jinping and President Vladimir Putin's lack of attendance
The US president said Chinese President Xi Jinping and Russian President Vladimir Putin have lost influence across the world by deciding to "walk away" from the summit in Glasgow where almost 200 countries are present.
Mr Biden told a press conference at the summit: "I indicated that China, Russia and Saudi Arabia not showing up is a problem. We showed up. We showed up.
"By showing up we’ve had a profound impact on the way, I think, the rest of the world is looking at the United States’s leadership role.
"I think it’s been a big mistake quite frankly, with respect to China not showing up. The rest of the world is going to look to China and say what value are they providing?
"They’ve lost an ability to influence people around the world and all the people here at COP, in the same way I would argue with regard to Russia."
Mr Biden said he cannot think of any two days when more progress has been achieved in dealing with global warming than the start of COP26.
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He said the whole world's attention is on the "gigantic issue" of the climate crisis and China and Russia simply "walked away".
"How can you do that and claim to be able to have any leadership now?" He said in reference to President Xi and President Putin.
“How can you do that and claim to be able to have any leadership now?” Asks Joe Biden as he decries China and Russia's decision not to attend COP26.
He added that the Russian tundra - above the Arctic Circle - is "literally burning" and that Mr Putin has "serious, serious climate problems" but he shows a lack of "willingness to do anything".
"I think the fact that America showed up and decided to lead and lay it out clearly what it wished to do," he added.
His comments came after the US led two major agreements in the opening days of the climate talks, including a pledge to end and reverse deforestation by 2030 - something more than 100 countries signed up to.
A second major commitment pledged by more than 80 countries was to reduce harmful methane emissions by 30% by 2030.
Prime Minister Boris Johnson echoed Mr Biden's optimism for the start of the 12 days of negotiations, claiming humanity has pulled one back against global warming at the summit.
Mr Johnson said world leaders had made great progress but accepted there is "a lot more to do", including on China's part.
The PM said the fact the president wasn't present "doesn't mean the Chinese are not engaging" and that "we're seeing some signs of progress".
Mr Johnson told a press briefing: "I think that we need China to make commitments, China has already made a substantial commitment in the sense that they've moved to net zero by the middle of the century, 2060 or before, as Xi Jinping says."