NBCUniversal Inc. November 20, 2019 3:11 am ‘Late Night': Al Gore Calls Climate Change Most Serious Challenge Al Gore calls climate change the most serious challenge human civilization has ever faced and talks about an upcoming global event for climate change awareness. US & World Videos 2:19 11-year-old celebrates teachers with appreciation snack cart 1:19 Met Gala 2024 after party looks: Cardi B, Lana Del Rey, EmRata 6:22 Craig Melvin compares ‘TODAY' crew to NASCAR 1:02 Judge indefinitely delays Trump's classified documents criminal trial 9:25 Zayn Malik opens up about 6-year journey to new album