Ocean heat hit a record high in 2018; the United Nations said on 28 March 2019, raising urgent new concerns about the threat global warming is posing to marine life. In its latest State of the Climate overview, the World Meteorological Organization (WMO) reaffirmed that the last four years had been the hottest on record -- figures previously announced in provisional drafts of the flagship report." 2018 saw new records for ocean heat content in the upper 700 meters," a WMO statement said. Last year also saw new heat records for the ocean's upper 2,000 meters. Some models predict the temperature of the top 2,000 metres of world's oceans will rise nearly 0.8 degrees Celsius by the end of the century if nothing is done to reduce greenhouse gas emissions, according to Science.  "There is no longer any time for delay," UN Secretary General Antonio Guterres warned, stressing that nations needed to come to his Climate Action Summit in September 2018 with "concrete, realistic plans" to reduce emissions.