Water temperatures are warming at an unprecedented rate, with 40% of global oceans currently experiencing a heat wave. It's the largest global ocean heat wave recorded since 1991. ABC News Chief Meteorologist Ginger Zee has more. WATCH the ABC News Livestream: bit.ly/3rzBHum SUBSCRIBE to ABC News: bit.ly/2vZb6yP WATCH MORE on abcnews.go.com LIKE ABC News on FACEBOOK: facebook.com/abcnews FOLLOW ABC News on TWITTER: twitter.com/abc #ABCNews #climatechange #globalwarming #heatwave #watertemperature