A new NOAA-sponsored report shows that unprecedented warming air temperature in 2016 triggered massive declines in sea ice and snow cover across the Arctic, and brought a record-breaking delay to fall sea ice freeze up. Learn more through our image highlights of the 2016 Arctic Report Card.
A record-smashing hurricane season in the central North Pacific. Water rationing in Puerto Rico. The biggest one-year jump in atmospheric carbon dioxide concentrations. These and more of 2015's extreme events had one thing in common: El Niño.