Packing away carbon isotopes

Article Abstract:

New research on the ratios of carbon isotopes 13C and 12C indicates that carbon-fractionating mechanisms may not satisfactorily account for the low levels of carbon dioxide (CO2) during the last ice age. Studies of ancient desert shrubbery buried by packrats and of air samples from Antarctic ice found that the glacial atmospheric delta 13C ratio was most likely 0.3 to 0.7% lower than in the modern, pre-industrial age. The biological pump and vertical shifts of dissolved carbon do not explain this low ratio in terms of the biogeochemical processes that move CO2 from the ocean surface to deep water.

Carbon, Carbon isotopes, Carbon cycle (Biogeochemistry), Carbon cycle

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Avoiding a permanent ice age

Article Abstract:

The presence of carbon dioxide, water vapor and other greenhouse gases in the primitive Earth's atmosphere may have prevented an irreversible climatic cooling due to the Sun's low output of radiation at the time. Ken Caldeira and James F. Kasting deduced from a paleoclimatic model that the carbon dioxide ice clouds produced by such cooling would have made the ensuing ice age endless. However, the lack of such an interminable glacial period indicates that the greenhouse gases counteracted the effect of low solar radiation to keep the Earth warm since it formed.

Solar radiation

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Tectonic forcing of late Cenozoic climate

Article Abstract:

The uplift or rise of the Tibetan plateau probably initiated the world-wide cooling in the Cenozoic era that eventually produced vast ice sheets in both the Northern and Southern Hemispheres. The Tibetan plateau is an elevated part of Asia centering on Tibet and including the Himalayan mountains. The Cenozoic uplift of this region may have had climatic feedbacks that reinforced the trend toward cooling especially by reducing atmospheric CO2 levels through tectonically induced chemical weathering.

Causes of, Natural history, East Asia, Geology, Stratigraphic, Stratigraphy, Global temperature changes, Cenozoic Era, Asia, Eastern

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