Mario Draghi has warned the leaders of the world’s 20 largest economies that “going it alone is simply not an option,” as they gathered in Rome to start a two-day race to reach a deal on global climate change targets.

The Rome G20 summit will set the tone for the COP26 meeting in Glasgow next week, with significant divisions remaining between countries over how far they are willing to acknowledge the threat of climate change and what further commitments they will make to fight it.

“Multilateralism is the best answer to the problems we face today. In many ways it is the only possible answer,” Draghi, Italy’s prime minister and host of the G20 this year, said in his opening comments on Saturday.

“From the pandemic, to climate change, to fair and equitable taxation, going it all alone is simply not an option. We must do all we can to overcome our differences”.

Hope for what can be achieved in Rome was tempered by the absence of several leaders from the first face-to-face G20 meeting in two years, with China’s president Xi Jinping and Russia’s Vladimir Putin, among those participating in the talks via videoconference.

Ministers from China, Russia, Japan, South Africa and Mexico had to pose for the opening “family photograph” in place of their leaders.

The countries that make up the G20 are responsible for an estimated 80 per cent of global carbon emissions and no progress on multilateral solutions to global warming is possible without them.

One of the most contentious issues this weekend is whether to include a pledge to quit coal in the final communique, a move opposed by some coal-dependent countries such as India, Russia and Australia.

Leaders are also discussing how to increase funding for climate issues. One option on the table is ringfencing a portion of the IMF special drawing rights for climate or coal-related projects.

The IMF issued $650bn in SDRs, a money-like instrument, to help with the pandemic recovery, with the richer countries saying they will reallocate their SDRs to poorer countries but that they have not yet decided how.

As the negotiations over the communique dragged on into Saturday, the paragraphs on climate had not yet been agreed. “The climate and energy text is the only part of the communique that is still wide open,” said a source close to the talks.

Securing the support of India’s prime minister Narendra Modi is seen as critical for the G20 outcome on coal, which is a high priority for the Italian hosts. India has not submitted any new climate pledges ahead of COP26, and remains firmly wedded to coal.

Earlier in the day, Boris Johnson, the British prime minister who will host COP26 in Glasgow, warned that it would be “very, very tough to get the agreement we need”.

Ahead of Saturday’s talks France’s Emmanuel Macron told the Financial Times that he hoped the G20 would agree to “accelerate the exit from coal power” and for rich countries to commit more financially to help developing countries meet their climate goals.

A final communique that will show the extent of the G20’s revised climate commitments will be released on Sunday afternoon.

The Rome summit has also provided world leaders with the opportunity to hold important bilateral meetings.

US president Joe Biden yesterday met Macron for the first time since a diplomatic spat between Paris and New York over a cancelled French submarine contract.

The leaders of the US, France, the UK and Germany were scheduled to hold a four-way meeting to discuss Iran on Saturday and later Italy’s president Sergio Mattarella will host a gala dinner for leaders and their partners.