The UN humanitarian chief has urged Israel to open more crossings into Gaza to allow a surge of aid, after Israel warned it would limit supplies into the territory over delays from Hamas in releasing the bodies of deceased hostages.

GENEVA — Heat-trapping carbon dioxide levels in the atmosphere jumped by the highest amount on record last year, soaring to a level not seen in human civilization and “turbo-charging” the earth’s climate and causing more extreme weather, the United Nations weather agency said Wednesday.