Earth's average temperature remained at a record high Wednesday after two days in which the planet reached unofficial records. It's the latest marker in a series of climate-change-driven extremes.The average global temperature was 62.9 degrees, according to the University of Maine's Climate Reanalyzer, a tool that uses satellite data and computer simulations to measure the world's condition. That matched a record set Tuesday and came after a previous record of 62.6 degrees was set Monday.