For the past quarter-century, the National Oceanic and Atmospheric Administration has been gathering data from more than 400 scientists around the world on climate trends.

The report on 2014 from these international researchers? On average, it was the hottest year ever — in the ocean, as well as on land.

There has been a lot of extreme weather in the Northern Hemisphere this year, including the recent torrential rains in Colorado, flooding in Europe, bitter cold in Florida and a heat wave in Alaska. And scientists say all of it is related to some odd behavior by the powerful air currents called the polar jet stream.