oceanic and atmospheric announced that it was the warmest in history. sea level rise were major stories throughout the year with unprecedented global protests, bringing up as well regularly, nns nbc news al roker traveled the globe to report on the stories that will define the next decade and beyond. >> reporter: when you're talking temperature, 2019 was one for the record books. this was the hottest july ever for the planet. five countries hit all-time national heat records. hottest month ever. >> across the globe, the hottest june, july and september, and the second hottest august, october and november in recorded history. i traveled to southeastern greenland where the arctic is warming twice as fast as