 As recently as 1975 many North Cascade glaciers were advancing due to cooler weather and increased precipitation that occurred from 1944 to 1976 . By 1987 the North Cascade glaciers were retreating and the pace had increased each decade since the mid @-@ 1970s . Between 1984 and 2005 the North Cascade glaciers lost an average of more than 12 @.@ 5 metres ( 41 ft ) in thickness and 20 – 40 percent of their volume . 
