BERLIN (AP) — Geopolitical tensions including the current crisis between Russia and Ukraine could hamper international efforts to curb global warming at a crucial time, U.S. climate envoy John Kerry said Friday.

Speaking at the annual Munich Security Conference, the former Secretary of State warned that the rise in the cost of energy stoked by the crisis may make consumers and governments wary of taking tough measures needed to reduce greenhouse gas emissions.

“It’s not going to be positive because it’s going to distract rather enormously,” Kerry said of the current tensions.

“The prices of fuel will inevitably rise even more,” he said. “It will push people towards the path of least resistance, which we are already too much locked into, and that will bring about the path of greatest destruction.”

Kerry, who has led the Biden administration’s international climate diplomacy efforts, noted that without Russia, China and other major emerging economies reducing their emissions of planet-warming gas, global goals to limit temperature rise by the end of the century can’t be met.

“It is dictated by simple mathematics and physics,” he said.

Scientists have said emissions need to drop drastically this decade to prevent the worst impacts of climate change, a warning that Kerry echoed during his comments in Munich.

“This is really the critical year during which we will either prove we’re serious and we’re going to try to do what we have to do in 10 years, or we can’t do it,” he said. “In which case we will be spending trillions of dollars cleaning up the mess and trying to cope with the crisis.”