An international climate policy expert at The Australian National University (ANU) has called on G20 leaders to take concrete steps to reduce fossil-fuel subsidies and reform global energy governance.
Dr Christian Downie said the G20 has been struggling to deal with fossil fuel subsidies, despite pledging to phase them out in 2009.
"Billions and billions of dollars are spent by national governments every year subsidising fossil fuels when climate scientists tell us we need to be rapidly reducing global emissions," Dr Downie said.
"We can no longer afford to be subsidising those fuels that are damaging our atmosphere and our oceans."
World leaders are gathering in Germany for the 2017 G20 summit in Hamburg, which is the first global summit since the United States withdrew from the Paris agreement on climate change.
He said action on fossil-fuel subsidies was hampered by countries such as OPEC member Saudi Arabia, the United States and Australia.
Dr Downie, a Fellow at the School of Regulation and Global Governance at the ANU College of Asia Pacific, said German Chancellor Angela Merkel has put climate and energy high on the G20 agenda.
"Chancellor Merkel, a scientist by training, will be keen to show the world that Germany continues to lead on climate change given the withdrawal of the United States from the Paris climate agreement in June," Dr Downie said.
Dr Downie is also calling for reform of the international energy architecture as agreed under Australia's G20 presidency in 2014.
He said the main global body, the International Energy Agency (IEA), which was set up in the 1970s in wake of the oil shocks to represent energy consumers is now out of date.
"Today, four of the top 10 energy consuming nations with 40 percent of the world's population-China, India, Brazil, and Russia-are not members of the IEA. This must change," he said.
"While the IEA has traditionally been focused on oil markets, in recent years it has turned its attention to renewable energy, but it needs to go a lot further.
"If it doesn't, we'll continue to see its role in this space challenged by other organisations like the International Renewable Energy Agency. It was set up under German leadership a few years ago in part, it would seem, to address the view that the IEA has not done enough in the climate energy space."