Dr. Ricky Rood, professor of Atmospheric, Oceanic and Space Sciences at the University of Michigan said that 30 straight years of rising temperatures proves that the climate has changed.

“If you are 30 years old,” Dr. Rood said, “you have never lived in a month where the temperature was below the 20th century average.”

“Every year has not gotten hotter,” he continued, “but you would not really expect every year to be systematically warmer than the previous year [because of varying weather patterns] … Each month, each year, you might not expect to be hotter and hotter, but if you look at averages that are say, maybe ten years long or even thirty years long, you would expect to see them getting systematically hotter.”

Watch Dr. Rood discuss the rising temperatures of the last 30 years.