G20 exclusive: Barack Obama to promise as much as $3bn to the Green Climate Fund which was attacked by Tony Abbott

Barack Obama will make a substantial pledge to a fund to help poor countries fight climate change, again putting the US at odds with Australia, which has argued against diplomatic efforts for G20 leaders to promise more contributions to the fund.

America plans to pledge at least US$2.5bn (AUS$2.88bn) and as much as US$3bn over the next four years to the Green Climate Fund, according to those briefed by administration officials. The fund aims to help poorer countries cut their emissions and prepare for the impact of climate change, and is seen as critical to securing developing-nation support for a successful deal on reducing emissions at the UN meeting in Paris next year.

Tony Abbott had previously insisted Australia would not make any contributions to the fund, although it is understood the Department of Foreign Affairs and Trade, which leads Australia’s negotiating position in international climate talks, has been considering whether Canberra should make a pledge. Sources said no final decision had been made.

Asked about the fund before last year’s UN climate meeting in Warsaw, the prime minister said: “We’re not going to be making any contributions to that.” It was reported that at one of its first cabinet meetings the Abbott government decided it would make no contributions to the fund.

Abbott disparaged the fund at the time, comparing it to a domestic fund championed by the former Greens leader Bob Brown, which he wants to abolish.

He told the Australian newspaper: “One thing the current government will never do is say one thing at home and a different thing abroad. We are committed to dismantling the Bob Brown bank [the Clean Energy Finance Corporation] at home so it would be impossible for us to support a Bob Brown bank on an international scale.”

Federal ministers raised strong objections to Australia’s commitment to the Green Climate Fund during the cabinet discussion before Warsaw, a meeting to which Australia controversially declined to send the environment minister, Greg Hunt, or any ministerial representative. Foreign minister Julie Bishop will attend this year’s meeting in Lima later this month.

In opposition Bishop raised strong concerns that money from the foreign aid budget was being directed towards the climate change fund. “Climate change funding should not be disguised as foreign aid funding,” she said, accusing the former government of introducing the now-repealed carbon tax to pay for contributions to the fund.

“This is a tax to gather revenue to redistribute it around the economy and to buy themselves some brownie points at the United Nations,” she said in 2011.

The government also pointedly dissented from support for the fund in a communique from last November’s Commonwealth Heads of Government meeting – a stance backed by Canada.

The US’s financial commitment will be unveiled as world leaders gather for the G20 summit in Brisbane. Australia has been fiercely resisting climate change discussions at the summit and does not want it distracting from its desired focus on “economic growth and jobs”. But the government was caught off guard when Obama and his Chinese counterpart Xi Jinping unveiled climate pledges on the eve of the summit.

The pledge to the Green Climate Fund is seen as critical to UN negotiations for a global climate deal. Developing countries have said they cannot sign on to emissions cuts at the Lima meeting without the funds.

Analysts said the $2.5bn figure under discussion before the Brisbane summit was just about enough to demonstrate that the US was willing to put up the cash.

“I think it’s a good signal for unlocking the negotiations for Paris in 2015,” said Alex Doukas, an international climate policy analyst at the World Resources Institute. Congress will still have to authorise the funds. But some analysts argue that it will be difficult for Republicans to cut out climate finance entirely.

The pledge from Obama could also help spur Britain and other countries to pay into a fund that so far has raised just under $3bn, well short of its initial $10bn target.

Jake Schmidt, who follows international climate negotiations for the Natural Resources Defence Council, said: “[Obama] is trying to use the G20 as a way to put pressure bilaterally and otherwise for countries to put their targets and their financing on the table.”

There were early signs the strategy was paying off. The Japanese prime minister, Shinzo Abe, was expected to announce a pledge of up to $1.5bn to the fund at the Brisbane summit, press reports said.

More than $2.8bn had been pledged before the US commitment – including $1bn by France and almost $1bn by Germany. More pledges are expected at a special conference in Berlin on 20 November.

Heather Coleman, a climate analyst at Oxfam, said the US-China deal earlier in the week had helped lay the groundwork for Obama to offer a pledge on climate finance.

“Now that we have demonstrated that China is willing to move forward it does make it more palatable for the US to put more money on the table for international climate finance which everyone knows is the essential key to unlocking negotiations. Without finance you just don’t get a global climate deal,” she said.