On Wednesday, both NASA and NOAA announced that the last five years have been the hottest years in history. Out of 19, 18 years have been the warmest in recorded history. The climate scientist Simon Donner conducts researches on human-induced climate change at the University of British Columbia. He said that the planet's 20 coldest years all occurred between 1884 and 1929. The coldest year on record occurred in 1904.