World leaders are returning to the United Nations in New York this week with a focus on boosting efforts to fight both climate change and the Covid-19 pandemic, which last year forced them to send video statements for the annual gathering.

As the coronavirus still rages amid an inequitable vaccine rollout, about a third of the 193 UN states are planning to again send videos, but presidents, prime ministers and foreign ministers for the remainder are due to travel to the United States...