GaianTundral Subtype

Cold Gaian worlds with periodic, or persistent, ice ages

Arcadia Winter
Image from Steve Bowers and John M Dollan
The world Arcadia has been terraformed into a GaianTundral subtype world, either by accident or design

GaianTundral worlds have 25-80% ocean cover. Compare with TundralXeric worlds with 0-25% ocean cover, and TundralPelagic worlds, with 80-100% coverage by icy oceans.

In its youth, certain conditions may contribute to initiate a runaway glaciation on a Gaian world. The largest limiting factor to this is the presence of life; however, the absence of a large amount of biomass, even in the form of microbial life, along with certain continental configurations, can foster the unrestricted growth of the polar caps and the freezing of the oceans. At the height of this climatic episode, the oceans can freeze up to depths of several hundred meters, and even the equatorial oceans may be covered Ironically, so much ice in the oceans precludes much atmospheric moisture, and so mountain glaciers tend to find their growth arrested, and surface winds may even erode them to a great degree.

The skies are quite clear, and the continents are almost completely dry, covered in freezing deserts reminiscent of the dry, ice-free valleys of Earth's Antarctica. However, the slow accumulation of carbon dioxide in the atmosphere, released by volcanic activity, will eventually bring about a catastrophic greenhouse effect, melting these worlds in the space of only a few tens to hundreds of thousands of years. The planet then falls into a period of acidic greenhouse (see below), and the entire cycle may continue over several hundred million years until continental arrangements and the development of life breaks the cycle.

Example: Arcadia (post terraforming)
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Development Notes
Text by John M. Dollan
Initially published on 20 November 2008.