A Costa Rican diplomat and former vice-president whose parents were refugees from the Holocaust has become the surprise frontrunner to lead the United Nations as its first female secretary general.Rebeca Grynspan, whose parents emigrated to Central America from Poland – and whose maternal grandparents were killed by the Nazis – is the current head of the UN conference on trade and development (UNCTAD), a body that has exhaustively tallied the economic damage inflicted by Israel’s occupation of the Palestinian territories.The current secretary general, António Guterres, will complete his second term on 31 December 2026 and under an informal system of...