Drafts of the G20's final communique showed little progress in terms of new commitments to curb pollution ahead of COP26 climate talks in Glasgow.
G20 leaders will gather for a second day of their Rome summit, with all eyes on whether they can deliver a meaningful commitment on climate change ahead of crucial UN talks.
The first day of the Rome summit on Saturday - the leaders' first face-to-face gathering since the start of the Covid pandemic - focused mainly on health and the economy, while climate and the environment is front and centre of Sunday's agenda.
Climate scientists and activists are likely to be disappointed unless late breakthroughs are made, with drafts of the G20's final communique showing little progress in terms of new commitments to curb pollution.
The G20 bloc, which includes Brazil, China, India, Germany and the United States, accounts for an estimated 80 percent of the global greenhouse gas emissions which scientists say must be steeply reduced to avoid climate catastrophe.
For that reason, this weekend's gathering is seen as an important stepping stone to the UN's "COP26" climate summit attended by almost 200 countries, in Glasgow, Scotland, where most of the G20 leaders will fly directly from Rome.
A fifth draft of the G20's final statement on Saturday did not toughen the language on climate action compared with previous versions, and in some key areas, such as the need to achieve net zero emissions by 2050, it softened it.
This mid-century target date is a goal that United Nations experts say is needed to cap global warming at 1.5 degrees Celsius seen as the limit to avoid a dramatic acceleration of extreme events such as droughts, storms and floods.