A fresh UN warning underscores how relentlessly the planet is heating up: global average temperatures are expected to stay at or near record highs this year and through the following four years. Every one of the 11 hottest years ever observed has occurred since 2015, and the UN’s weather and climate agency says that pattern is poised to persist, with another hottest-ever year considered "likely" before 2031. The World Meteorological Organization (WMO) said there is a 75% chance that the average temperature across the…