UN Secretary-General António Guterres issued the unnerving alert to audiences at the COP27 climate conference in Egypt, telling delegates that “we are in the fight of our lives, and we are losing.”

“The clock is ticking,” he said. “Greenhouse gas emissions keep growing, global temperatures keep rising, and our planet is fast approaching the tipping point that will make climate chaos irreversible. We are on a highway to climate hell with our foot still on the accelerator.”

The UN chief acknowledged that conflicts including the war in Ukraine have had “dramatic” global impacts, but he said it was “unacceptable, outrageous, and self-defeating” for lawmakers to put climate change “on the back burner.”

“Today’s crises cannot be an excuse for backsliding or greenwashing,” he told attendees at the summit. “Human activity is the cause of the climate problem, so human action must be the solution.”

Noting that “in just days” the human population would cross the threshold of 8 billion people, Guterres said the looming milestone “puts into perspective what this climate conference is all about.”

“How will we answer when baby 8 billion is old enough to ask, ‘What did you do for our world and for our planet when you had the chance?’” he questioned. “The answer is in our hands.”

Guterres’s dire warnings on Monday came as world leaders gathered in the Egyptian city of Sharm el-Sheikh for the UN’s annual COP conference, and a day after provisional findings from a UN study revealed that the last eight years have been the warmest on record.

As the preliminary report was released on Sunday, Guterres described it as a “chronicle of climate chaos” that detailed the catastrophic speed of climate change.

COP27 has been described by organizers as “a defining moment in the fight against climate change.”

The conference opened on Sunday with the key aim of ensuring “full implementation” of the Paris Agreement—a landmark treaty adopted by 196 parties in 2015 that aims to keep global temperatures from exceeding 2 degrees Celsius above pre-industrial levels.  

While the absolute limit signatories are aiming for is 2 degrees Celsius, the treaty has a target of limiting warming to 1.5 degrees Celsius above pre-industrial temperatures.

A separate UN report released ahead of COP27 said global efforts remained insufficient to meet the goal of 1.5 degrees by the end of the century, and that the climate pledges of 193 parties to the Paris Agreement could actually be putting the world on track for 2.5 degrees Celsius of warming.

The organization said on Sunday that since COP26 in Glasgow last year, only 29 out of 194 countries had come forward with tightened national plans.

Elsewhere on Sunday, the WHO issued a “grim reminder” that the climate crisis was making people sick and jeopardizing lives, calling on leaders to “put health at the heart of [COP27] negotiations.” Between 2030 and 2050, the organization said, climate change is expected to cause approximately 250,000 additional deaths every year.

According to the latest statistics from Our World in Data, China, the U.S., and India are the world’s biggest polluters, being the countries responsible for the biggest proportion of global greenhouse gas emissions in 2019.

The organization’s figures also show that in 2020, China was responsible for a third of global CO2 emissions, while the U.S. was responsible for 13.5%.