BERLIN — Delivering the latest stark news about climate change on Sunday, a United Nations panel warned that governments are not doing enough to avert profound risks in coming decades. But the experts found a silver lining: Not only is there still time to head off the worst, but the political will to do so seems to be rising around the world.

In a report unveiled here, the Intergovernmental Panel on Climate Change found that decades of foot-dragging by political leaders had propelled humanity into a critical situation, with greenhouse emissions rising faster than ever. Though it remains technically possible to keep planetary warming to a tolerable level, only an intensive push over the next 15 years to bring those emissions under control can achieve the goal, the committee found.

“We cannot afford to lose another decade,” said Ottmar Edenhofer, a German economist and co-chairman of the committee that wrote the report. “If we lose another decade, it becomes extremely costly to achieve climate stabilization.”

The good news is that ambitious action is becoming more affordable, the committee found. It is increasingly clear that measures like tougher building codes and efficiency standards for cars and trucks can save energy and reduce emissions without harming people’s quality of life, the panel found. And the costs of renewable energy like wind and solar power are falling so fast that its deployment on a large scale is becoming practical, the report said.