Himalayan Rock Weathering May Not Have Caused Cooling of Earth
Researchers at Rutgers
University-New Brunswick have questioned the Himalayan Rock weathering
hypothesis that is believed to have caused long-term cooling of the Earth much
ahead of the recent global warming phenomenon.
The scientists Yair Rosenthal of
Department of Marine and Coastal Sciences and doctoral student William Si said
that accumulation of calcium carbonate in the deep sea happened over a period
of 15 million years suggesting that rock weathering may not be responsible for
the long term cooling.
Over millions of years, the
weathering of rocks captured carbon dioxide and rivers carried it to the ocean
as dissolved inorganic carbon, which is used by algae to build their calcium
carbonate shells. When algae die, their skeletons fall on the seafloor and get
buried, locking carbon from the atmosphere in deep-sea sediments.
Meanwhile, the scientists –
surprisingly – also found that algae called coccolithophores adapted to the
carbon dioxide decline over 15 million years by reducing their production of
calcium carbonate. This reduction apparently was not taken into account in
previous studies.Many scientists believe that ocean acidification from high
carbon dioxide levels will reduce the calcium carbonate in algae, especially in
the near future. The data, however, suggest the opposite occurred over the 15
million years before the current global warming spell.Rosenthal’s lab is now
trying to answer these questions by studying the evolution of calcium and other
elements in the ocean.
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