NEW : ( CNN ) -- Last year 's extreme weather could be `` the new normal , '' environmentalist says . NOAA declares 2012 the hottest on record . Every state in the Lower 48 saw above-average temperatures ; 19 set their own records . The U.S. is also experiencing its warmest winter since record-keeping began in 1880.
NEW : Last year 's extreme weather could be `` the new normal , '' environmentalist says . NOAA declares 2012 the hottest on record . Every state in the Lower 48 saw above-average temperatures ; 19 set their own records . The U.S. is also experiencing its warmest winter since record-keeping began in 1880.