The final tally is in: 2015 was the hottest year in recorded history—by a record-breaking margin. On Wednesday, NASA and the National Oceanic and Atmospheric Administration (NOAA) announced the official record for last year’s runaway temperatures, which by NOAA’s calculation hit an average of 58.62 degrees Fahrenheit (14.79 degrees Celsius). That’s 1.62 (F) degrees hotter than any average year in …