United Nations Secretary General Antonio Guterres told countries gathered at the start of the COP27 summit in Egypt on Monday they face a stark choice: work together now to cut emissions or condemn future generations to climate catastrophe.

The speech was intended to set an urgent tone as governments sit down for two weeks of talks on how to avert the worst impacts of climate change, even as they are distracted by Russia’s war in Ukraine, rampant consumer inflation and energy shortages.

"Humanity has a choice: cooperate or perish,” Guterres told delegates gathered in the seaside resort town of Sharm el-Sheikh. Leaders from countries from Britain to Saudi Arabia were scheduled to speak later in the day.

Guterres called for a pact between the world's richest and poorest countries to accelerate the transition from fossil fuels and speed up delivery of the funding needed to ensure poorer countries can reduce emissions and cope with the unavoidable impacts of warming that has already occurred.

“The two largest economies – the United States and China – have a particular responsibility to join efforts to make this pact a reality,” he said.

Guterres asked countries to agree to phase out the use of coal, one of the most carbon-intense fuels, by 2040 globally, with members of the Organisation for Economic Cooperation and Development hitting that mark by 2030.

Despite decades of climate talks - the Egypt COP is the 27th Conference of the Parties - progress has been insufficient to save the planet from excessive warming as countries are too slow or reluctant to act, he noted.

“Greenhouse gas emissions keep growing. Global temperatures keep rising. And our planet is fast approaching tipping points that will make climate chaos irreversible,” he said. “We are on a highway to climate hell with our foot on the accelerator.”

Signatories to the 2015 Paris climate agreement pledged to achieve a long-term goal of keeping global temperatures from rising more than 1.5 °C above pre-industrial levels.

Scientists have set this as the ceiling for avoiding catastrophic climate change.

Guterres said that to keep any hope alive of meeting that goal means achieving global net zero emissions by 2050.

"It is either a Climate Solidarity Pact – or a Collective Suicide Pact," he said.