Mr Abbott gave an impassioned defence of coal and, reportedly, argued against inserting a line in the communique recommending the abolition of fossil fuel subsidies, an objective of the G20 for many years. Coal-fired power stations are the biggest contributor to rising global carbon emissions that are warming the planet. Mr Obama is understood to have spoken forcefully against Mr Abbott's position on fossil fuel subsidies. The final communique calls on G20 members to "rationalise and phase out inefficient fossil fuel subsidies". Mr Abbott had support from Saudi Arabia and Canada, but countries led by the US and Europe remained steadfast. "The most difficult discussion was on climate change," an EU official told reporters on condition of anonymity, Reuters reported.

"This was really trench warfare, this was really step by step by step. In the end we have references to most of the things we wanted." The communique included references to taking practical measures to combat global warming and an explicit endorsement of the climate fund. As revealed by Fairfax Media, the communique includes a line: "We reaffirm our support for mobilising finance for adaptation and mitigation such as the Green Climate Fund." The inclusion of a detailed passage on climate change comes despite the issue not being on the formal agenda of the G20 summit and Mr Abbott's insistence that the focus of discussions should be on economic reform. Mr Abbott has said previously he opposed any financial contribution to the climate fund, which was reportedly described in a Cabinet document as a measure that amounted to "socialism masquerading as environmentalism".

The Green Climate Fund aims to assist poor nations combat climate change and relies primarily on funding from governments and private firms in industrialised countries. US president Barack Obama announced the US would devote $US3 billion to the fund, before he made a rallying call on Saturday for global action to curb greenhouse gas emissions. Japan pledged it would contribute $US1.5 billion to the climate fund on Sunday, taking the total commitment of nations so far to about $US8 billion. The fund wants to raise $US10-15 billion by the end of the month. Last week, the US and China jointly unveiled an historic commitment, albeit non-binding, to curb carbon emissions that scientists say are primarily responsible for raising the globe's temperature. While Treasurer Joe Hockey said the first draft of the communique mentioned the dangers of climate change, it is likely the reference will be far more extensive than Australia originally wanted. The EU official also said China had also been persuaded to back a key anti-corruption measure for members to co-operate to uncover the beneficial ownership of companies and bank accounts, Reuters reported.