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Why were continental ice sheets mostly absent during the Cretaceous Period?
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Cretaceous Period
Distribution of landmasses, mountainous regions, shallow seas, and deep ocean basins during the late Cretaceous Period. Included in the paleogeographic reconstruction are the locations of the interval's subduction zones.
Continental ice sheets were almost entirely absent during the Cretaceous Period because the Earth experienced a prolonged "greenhouse" climate, characterized by temperatures significantly warmer than those of the present day.12
This warmth was global in scale, with tropical to subtropical conditions extending to high latitudes and temperate conditions reaching the poles. Several factors contributed to this environment:1
- Atmospheric Composition: The period is associated with "greenhouse" episodes, which are linked to higher concentrations of atmospheric carbon dioxide, a primary greenhouse gas that traps heat.2
- Equable Temperatures: The temperature gradient between the Equator and the poles was roughly half of what it is today, preventing the extreme cold necessary for the formation of large-scale ice sheets.1
- Oceanic Influence: Diminished ocean circulation and the distribution of warm waters via the Tethys Sea helped maintain these elevated global temperatures.13
While temperatures fluctuated and cooled slightly toward the end of the period, the climate remained much warmer than today, restricting ice and glaciers to only the highest mountain ranges.1