US President Joe Biden told the United Nations General Assembly on Tuesday he would work with Congress to double funds by 2024 to $11.4 billion per year to help developing nations deal with climate change.

The funding would help achieve a global goal set more than a decade ago of $100 billion per year to support climate action in vulnerable countries by 2020.

"The best part is, making these ambitious investments isn't just good climate policy, it's a chance for each of our countries to invest in ourselves and our own future," Mr Biden told the annual gathering of world leaders. Mr Biden made the commitment less than six weeks before the Oct 31-Nov 12 COP26 Climate Change Conference in Glasgow, Scotland.

Core elements of his climate change agenda remain tied to the fate of infrastructure and budget legislation under intense negotiation in Congress, raising the risk that he could arrive at the summit empty handed. The host of the conference, British Prime Minister Boris Johnson, said that meeting the climate finance target is key to building trust between developing and developed nations ahead of new negotiations since developed countries have failed to mobilise the $100 billion per year pledge by the original goal year of 2020. Developing countries have been urging industrialised nations to offer financial assistance to help them both rapidly adopt clean energy technologies enabling them to avoid the use of fossil fuels and bolster their defences against the impacts of climate change from sea level rise to extreme heat. Some environmental groups welcomed the new pledge as a much needed boost for the Paris climate agreement ahead of November's summit in Scotland but others were less impressed by Mr Biden's speech, including Swedish activist Greta Thunberg.

"President Biden's commitment to scaling up international climate finance to $11.4 billion per year by 2024 is a welcome and much-needed sign that the United States is finally taking its global climate responsibilities seriously," said Rachel Cleetus, policy director at the Union of Concerned Scientists. But as the world's second biggest greenhouse gas emitter, other campaigners said the pledge still falls short. "The US is still woefully short of what it owes and this needs to be increased urgently," said Mohamed Adow, director of Power Shift Africa.

Greta Thunberg criticised climate speeches and pledges at the UN as hollow. "It's quite easy to understand why the world's top emitters of CO2 and the biggest producers of fossil fuels want to make it seem like they're taking sufficient climate action with fancy speeches. The fact that they still get away with it is another matter," she wrote on Twitter.

Mr Johnson and European Commission President Ursula van der Leyen called out the United States on Monday for lagging behind on delivering its share. An analysis by the World Resources Institute shows that even with the US increasing its climate aid commitment to $11.4 billion by 2024, it pales in comparison to the $24.5 billion that the EU spent on climate aid in 2019. Another report released last week - ahead of the Joe Biden announcement - by the Organisation for Economic Cooperation and Development said that overall, rich countries fell short of the $100 billion goal, contributing just $79.6 billion in 2019.