SANTA CRUZ PROVINCE, ARGENTINA - NOVEMBER 27:  Ice calves at the Perito Moreno glacier in Los Glaciares National Park, part of the Southern Patagonian Ice Field, the third largest ice field in the world, on November 27, 2015 in Santa Cruz Province, Argentina. The majority of the almost 50 large glaciers in Los Glacieres National Park have been retreating during the past fifty years due to warming temperatures, according to the European Space Agency (ESA). The United States Geological Survey (USGS) reports that over 68 percent of the world's freshwater supplies are locked in ice caps and glaciers. The United Nations climate change conference begins November 30 in Paris.  (Photo by Mario Tama/Getty Images)
SANTA CRUZ PROVINCE, ARGENTINA - NOVEMBER 27:  Ice calves at the Perito Moreno glacier in Los Glaciares National Park, part of the Southern Patagonian Ice Field, the third largest ice field in the world, on November 27, 2015 in Santa Cruz Province, Argentina. The majority of the almost 50 large glaciers in Los Glacieres National Park have been retreating during the past fifty years due to warming temperatures, according to the European Space Agency (ESA). The United States Geological Survey (USGS) reports that over 68 percent of the world's freshwater supplies are locked in ice caps and glaciers. The United Nations climate change conference begins November 30 in Paris.  (Photo by Mario Tama/Getty Images)

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Undeniable climate crisis facts (2018)

Glaciers are melting; sea levels are rising. And 20 of the hottest years on record have occurred since 1996. CNN's Jennifer Gray reports the facts about the climate crisis.

Undeniable climate crisis facts (2018)

Glaciers are melting; sea levels are rising. And 20 of the hottest years on record have occurred since 1996. CNN's Jennifer Gray reports the facts about the climate crisis.