A commitment from the Group of Seven wealthy countries to phase out fossil fuels faster has been welcomed as a potential step towards a global deal for all countries to do the same, but is facing criticism for not matching the pledge with firm action.
G7 countries' climate ministers on Sunday agreed - for the first time - to speed up their phaseout of the fossil fuel consumption causing climate change, although they did not set a firm date for doing this.
In a joint statement at their meeting in Sapporo, Japan, the ministers agreed "to accelerate the phase-out of unabated fossil fuels so as to achieve net zero in energy systems by 2050 at the latest".
"This is an important step forward, after the failure of COP27 on this point at the end of last year," said French Energy Transition Minister Agnès Pannier-Runacher.
At last year's COP27 UN climate summit, countries failed to agree a deal on phasing down fossil fuel energy. A proposal by India to do this won support from more than 80 governments, but was opposed by Saudi Arabia and other oil- and gas-rich countries.
Some, including the 27-country European Union, are hoping to revive the idea ahead of this year's U.N. climate summit, which begins on 30 November in Dubai.
While not legally binding, the idea behind a global deal to gradually quit fossil fuels would be to create a powerful "north star" to guide future climate negotiations, government policies and investments towards clean energy and industries.
"If you could get a consensus decision that this is the direction of travel, that would be huge," Alden Meyer, senior associate at climate think-tank E3G, told Reuters.
But Meyer, who has attended UN climate negotiations since they began in 1991, warned of significant hurdles to clinching the pledge. It took more than two decades of UN climate negotiations before countries even mentioned fossil fuels in a summit statement - which was in 2021 - amid pushback from fossil fuel-producing countries and industries.
Insufficient financial support from wealthy countries to help developing countries switch to clean energy could also weaken the G7's leverage in bringing other countries on board with a commitment to eventually quit oil and gas.
Wealthy countries have still not met a promise to deliver $100 billion per year, starting in 2020, to help poorer countries cut emissions and cope with climate change. That amount falls far short of their actual needs, but has become symbolic of wealthy countries' failure to deliver promised climate funds.
Meyer said a G7 leaders meeting next month could offer an opportunity to back up their call for a fossil fuel phaseout with strong commitments to financially help developing nations to transition.
"That could go a long way to greasing the skids for a political deal on a managed transition away from fossil fuels," he said.
The need to back the fossil fuel phaseout pledge with cash was echoed by Gillian Nelson, policy director at the non-profit We Mean Business coalition, which works with companies and investors on climate action.
Nelson said G7 governments spent roughly $33 billion a year on fossil fuel subsidies that could be redirected to help unleash private cash for clean energy.
"The most efficient way to ensure a smooth and just transition to a clean energy system is to redirect these subsidies now," she said.
Stepping stones that could be used to build momentum for a fossil fuel commitment ahead of COP28 include a June summit hosted by France, aimed at scaling up finance for developing countries, and a September G20 leaders meeting hosted by India - author of the proposal at last year's climate summit to phase down fossil fuels.
Egypt's foreign minister Sameh Shoukry, president of last year's UN climate summit, has said consultations will continue ahead of COP28 on whether to call for a phaseout of fossil fuels.
"I think there's a general recognition of the importance of reducing reliance on fossil fuels," Shoukry said last month after a meeting of ministers in Copenhagen, where attendees included the United Arab Emirates' incoming COP28 summit president, Sultan Al-Jaber.
Pushing through a deal on phasing out fossil fuels would depend on the UAE rallying political support - including among other oil and gas producing nations like Saudi Arabia, which opposed the proposal at last year's summit, said Luca Bergamaschi, co-founder of Italian climate think tank ECCO.
But Bergamaschi said that widespread support was unlikely to be won without the G7 - since the most developed economies must offer developing countries a map to achieving the goal by offering financial support and scaling up clean energy.
"Where the G7 should show much more leadership is how, in practice, you are going to do that?" he said