The chief of the World Health Organization said the expanding monkeypox outbreak in more than 70 countries is an “extraordinary” situation that now qualifies as a global emergency, a declaration Saturday that could spur further investment in treating the once-rare disease and worsen the scramble for scarce vaccines. WHO Director-General Tedros Adhanom Ghebreyesus made the decision to issue the declaration despite a lack of consensus among members of WHO’s emergency committee. It was the first time the chief of the U.N. health agency has taken such an action.