International efforts, such as the Paris Agreement, aim to reduce greenhouse gas emissions. But experts say countries aren’t doing enough to limit dangerous global warming.

The U.S. government responds to scores of disasters each year in coordination with foreign, state, and local partners, but more frequent and severe storms, fires, and floods are straining resources.

The General Assembly hosts a much-watched debate of world leaders annually. Its 2023 meeting is expected to emphasize climate change, the United Nations’ Sustainable Development Goals, and the war in…