The collision between India and Asia set off events that likely caused long-term cooling in Earth’s climate
When the tectonic plate carrying
Before the collision, volcanoes along the rim of southern
Simultaneously, erosion of rocks on the Indian subcontinent — in particular, the chemical weathering of a large amount of basaltic rocks formed from volcanic eruptions just a few million years earlier — consumed large volumes of carbon dioxide. That double whammy, the researchers speculate, caused atmospheric concentrations of carbon dioxide to plummet, cooling Earth significantly.
About 120 million years ago, the tectonic plate that carried
what is now the Indian subcontinent split from Gondwana, the supercontinent
that sat astride the South Pole. The subcontinent began to move quickly
northward, at times migrating about 25 centimeters per year, says
About 65 million years ago, before the subcontinent reached the tropics, a spate of volcanic activity on the subcontinent lasting a million years spewed about 4 million cubic kilometers of basalt lava — an outpouring that contributed to the demise of the dinosaurs, some scientists propose.
By about 50 million years ago, when
Between 50 million and 34 million years ago, as erosion and
other geological processes sapped the greenhouse gas from the atmosphere, CO2
levels dropped to modern-day, pre-industrial levels of about 300 parts per
million. Other changes in landmass distribution in the Southern Hemisphere
resulted in changes in ocean currents in the region, which led to further
cooling and the development of permanent ice sheets on
The new findings “describe a perfect storm of carbon cycling,”
says Mimi Katz, a paleooceanographer at Rensselaer Polytechnic Institute in
“This is a very interesting and imaginative paper,” says
Karl Turekian, a geochemist at
The scenario set out in the new paper “is plausible,” says
William F. Ruddiman of the
Kent, D.V., and G. Muttoni. In press. Equatorial convergence of India and early Cenozoic climate trends. Proceedings of the National Academy of Sciences.