Atlantic Ocean's Warm vs. Cool Cycles

This study linked major flooding across Europe and North America to the Atlantic Multidecadal Oscillation -- a natural pattern of warm and cool phases in North Atlantic sea-surface temperatures. We’ve been in a warm phase since the late-1990s. By Giorgiogp2 (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons