The Pope has warned major oil company heads that there was “no time to lose” to address climate change and urged them to speed up the transition away from fossil fuels.

“This is a challenge of epochal proportions,” said Pope Francis on June 9, as he addressed a summit of energy leaders at the Vatican that included the chief executives of BP, ExxonMobil, Equinor and Eni.

The Pope said it was “disturbing and a cause for real concern” that carbon emissions had continued to rise following the Paris climate agreement that commitments to keeping the rise in global temperatures to less than two degrees Celsius from the pre-industrial era.

“Even more worrying is the continued search for new fossil fuel reserves, whereas the Paris agreement clearly urged keeping most fossil fuels underground,” he added, speaking to an audience that included Lord John Browne, the former head of BP, and Larry Fink, the BlackRock chief.

The unusual gathering of top energy chiefs at the Vatican underscores the growing role that the Roman Catholic Church has played in advocating climate protection—as well as oil and gas companies’ increasing focus on this issue.

Shell vowed last year to cut its carbon footprint in half by 2050, including its own emissions as well as those from the use of its products. This year BP and ExxonMobil announced their low-carbon strategies, which include curbing leaks of methane, a potent greenhouse gas, and reducing emissions from their operations.

Pope Francis said those efforts were “commendable” but might not be enough to “turn the corner in time” to limit global warming.

While the Pope has previously met business leaders one-on-one, including Facebook’s Mark Zuckerberg, these are usually individual audiences rather than big groups.

The energy summit, titled “Energy Transition and Care for Our Common Home”, took place on Friday and Saturday in Rome, and the Pope addressed the group on Saturday morning.

The Pope called on oil and gas companies to find ways to meet the world’s energy needs—and provide energy access to people who do not have it—while simultaneously transitioning to energy sources that are less polluting.

He admonished the gathering to do more, saying: “Civilization requires energy, but energy use must not destroy civilization!”

Claudio Descalzi, chief executive of Eni, echoed the remarks, telling the group the industry faced a “double challenge” of providing access to energy for a growing world population while cutting its carbon footprint.

In developed countries, the shift in energy might be towards lower-carbon sources, Mr Descalzi added, but in lower-income countries “development is triggered firstly by addressing access to energy, which spins off benefits related to industrial growth, economic diversification, health and education”.

Lord Browne said that hearing from the Pope and other Catholic leaders in the Vatican had ensured a thoughtful discussion.

“No-one can be unaffected when by going into those 16th-century surroundings created by Pope Pius IV,” he said. “When you go to the Vatican and see the Pope, it changes the tone of the debate. It makes it much more serious, and much more real.”

As chief executive of BP in 1997, Lord Browne shocked much of oil industry when he said companies should “begin to take precautionary action” against the potential threats from global warming.

Two decades later, he said, the industry was talking “much more seriously” about climate change. The general agreement in the meeting at the Vatican was that “we want to get carbon dioxide and methane emissions down to safe levels, and eventually to zero”, and that technology to do that was available.

Under Pope Francis’ leadership the Catholic church has become more active in climate causes, and in recent weeks dozens of Catholic institutions announced they were divesting fossil fuel investments.

Additional reporting by James Politi in Rome