Although the United States has experienced arctic cold recently, it is important to put this in perspective. According to the National Oceanic and Atmospheric Administration, November 2013 was the hottest November globally ever recorded and was also the 345th consecutive month with a global temperature higher than the 20th century average. The 12 warmest years on record have all occurred since 1998, according the Union of Concerned Scientists. The Arctic ice cap continues to melt and atmospheric carbon dioxide continues to rise. More than 97 percent of the world's scientists agree that global warming is happening and that human activity is the primary cause.