Answer:

iceages

Answer	Crossword Clue
ICEAGES	Times of widespread glaciation
ICEAGES	Colds that don't go away for a long time
ICEAGES	Super-cold periods

ICEAGES	Deep-freeze periods
ICEAGES	Major cold spells
ICEAGES	Glacial periods
ICEAGES	Deep freezes, so to speak
ICEAGES	Cooling-off periods
ICEAGES	No mere cold snaps
ICEAGES	Periods in contrast to global warming
ICEAGES	Periods in stark contrast to global warming

ICEAGES	They lead to major topographical changes
ICEAGES	Periods with the largest glaciers
ICEAGES	Subjects in paleoclimatology