By redoubling their climate efforts, he said, cities, states and corporations could achieve, or even surpass, the pledge of the administration of former President Barack Obama to reduce America’s planet-warming greenhouse gas emissions 26 percent by 2025, from their levels in 2005.

It was unclear how, exactly, that submission to the United Nations would take place. Christiana Figueres, a former top United Nations climate official, said there was currently no formal mechanism for entities that were not countries to be full parties to the Paris accord.

Ms. Figueres, who described the Trump administration’s decision to withdraw as a “vacuous political melodrama,” said the American government was required to continue reporting its emissions to the United Nations because a formal withdrawal would not take place for several years.

But Ms. Figueres, the executive secretary of the United Nations Framework Convention on Climate Change until last year, said the Bloomberg group’s submission could be included in future reports the United Nations compiled on the progress made by the signatories of the Paris deal.