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A 'snowball Earth' climate triggered by continental break-up through changes in runoff
Yannick Donnadieu1, Yves Goddéris, Gilles Ramstein
1Laboratoire des Sciences du Climat et de l'Environnement, CNRS-CEA, 91191, Gif sur Yvette, France. tiphe@lsce.saclay.cea.fr
Nature
|March 19, 2004
Summary
Plate tectonics and volcanic activity during the Proterozoic eon may have triggered a
Area of Science:
- Geosciences
- Climate Science
- Paleoclimatology
Background:
- Geological and paleomagnetic evidence suggests global ice sheets reached the Equator during the late Proterozoic eon (800–550 million years ago).
- This 'snowball Earth' hypothesis requires significantly lower atmospheric carbon dioxide (CO2) levels than today, a condition whose cause remains debated.
- A fainter sun (6% dimmer) is also considered a factor in snowball Earth scenarios.
Purpose of the Study:
- To investigate the role of paleogeographic changes preceding the Sturtian glaciation (750 million years ago) in regulating atmospheric CO2.
- To model the impact of continental break-up and volcanic activity on long-term CO2 evolution.
Main Methods:
- Utilized the coupled climate-geochemical model GEOCLIM.
- Simulated the effects of Rodinia's continental break-up on runoff, continental weathering, and atmospheric CO2 concentrations.
- Incorporated the weathering impact of basaltic lava flows associated with Rodinia's breakup.
Main Results:
- Simulations show that Rodinia's break-up increased runoff, leading to enhanced continental weathering and a decrease in atmospheric CO2 by 1,320 parts per million (ppm).
- The combined weathering effects of increased runoff and basaltic eruptions significantly reduced CO2 levels.
- These CO2 reductions are sufficient to trigger a snowball glaciation.
Conclusions:
- Tectonic shifts, specifically the break-up of Rodinia, played a crucial role in transitioning Earth from a 'greenhouse' to an 'icehouse' climate during the Neoproterozoic era.
- Continental weathering, amplified by volcanic activity, is a plausible mechanism for generating the low CO2 conditions necessary for snowball Earth.
- This study provides a quantitative link between tectonic processes and extreme climate events in Earth's history.
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