Other Climate Changes
	q The snow cover has decreased by about 10% since the late 1960s. q Northern hemisphere spring and summer sea-ice extent has decreased by about 10 to 15% since the 1950s. q El Nino phenomenon has been more frequent, persistent, and intense since the mid-1970s. q No significant trends of Antarctic sea-ice extent are apparent since 1978. q No systematic changes in the frequency of tornadoes, thunder days, or hail events are evident in the limited areas analyzed.