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2 Earth’s cold biosphere Earth’s biosphere is cold, with 14 % being polar and 90 % (by volume) cold ocean <5 oC. More than 70 % of Earth’s freshwater occurs as ice and a large portion of the soil ecosystem (~20%) exists as permafrost. There is even evidence that bacteria proliferate in high altit...
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| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.504.9017 http://salegos-scar.montana.edu/docs/Literaturedocs/Earth%27s_Icy_Biosphere.pdf |
| Summary: | 2 Earth’s cold biosphere Earth’s biosphere is cold, with 14 % being polar and 90 % (by volume) cold ocean <5 oC. More than 70 % of Earth’s freshwater occurs as ice and a large portion of the soil ecosystem (~20%) exists as permafrost. There is even evidence that bacteria proliferate in high altitude supercooled cloud droplets (Sattler et al. 2000) using organic acids and alcohols for growth. Microorganisms in sea ice were noted by early sailors and first studied as a scientific curiosity by Bunt (1964). At maximum extent, sea ice covers some 5 % of the Northern Hemisphere and 8% of the Southern Hemisphere and accounts for about 67 % of the Earth’s ice cover. Despite the global significance of sea ice, only recently has it been explored for novel microorganisms (Bowman et al. 1997; Junge et al. 2002; Thomas and Dieckmann 2002). Recent studies of microbial diversity in polar oceans have shown a predominance of Archaea in the subgroup Chrenarchaeota (DeLong et al. 1994). Previous to this discovery, Archaea were thought to be confined to thermal systems. Paleoclimate records for the past 500,000 years have shown that the surface temperature on Earth has fluctuated drastically, with four major glaciations occurring |
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