UNITED NATIONS — The United Nations Climate Action Summit on Monday was meant to highlight concrete promises by presidents, prime ministers and corporate executives to wean the global economy from fossil fuels to avoid the worst effects of global warming.

But despite the protests in the streets, China on Monday made no new promises to take stronger climate action. The United States, having vowed to pull out of the Paris Agreement, the pact among nations to jointly fight climate change, said nothing at all. A host of countries made only incremental promises.

The contrast between the slow pace of action and the urgency of the problem was underscored by the Swedish climate activist Greta Thunberg, 16, who excoriated world leaders for their “business as usual” approach. “The eyes of all future generations are upon you,” she said, her voice quavering with rage. “If you choose to fail us, I say we will never forgive you.”

There were some concrete measures. By the end of the day, 65 countries had announced efforts to achieve net-zero emissions by 2050, several asset fund managers said they would aim to get to a net-zero portfolio of investments by the same year, and dozens of businesses said they would aim to abide by the Paris Agreement targets .