A close-up view of the crack spreading across the ice shelf of Pine Island Glacier shows the details of the boulder-like blocks of ice that fell into the rift when it split, from this handout image captured by the Digital Mapping System (DMS) aboard NASA's DC-8 October 26, 2011. REUTERS/NASA/DMS/Handout
Climate scientists are studying the underlying causes of previous mass extinction events to gain a better understanding of what may happen as greenhouse gas emissions raise global temperatures.
It's been speculated that if all fossil fuels are burned up until the 22nd century, global temperatures will rise by as much as 10 degree Celsius. That temperature would be similar to what occurred during the Paleocene/Eocene Thermal Maximum event in the early Cenozoic era.
During the PETM event, Earth's surface temperature rose by around 6 to 8 degree Celsius. The rise in temperature led to permanent changes in the world's ecosystems.
For example, the PETM event caused the mass extinction of marine protozoa known as benthic foraminifera.
Although certain land mammal species were also wiped out, in their place new mammal species appeared, like primates and horses.
There are several possibilities being studied as to what caused the PETM event. These include volcanic eruptions on a massive global scale, a forced increase in temperature due to Earth's orbit, an abrupt release of methane gas into the atmosphere and deep ocean heat circulation.
Another extreme global warming event that occurred much earlier, during the Cambrian period, has been labeled "hyperwarming" by Dr. Ed Landing, a state paleontologist and paleontology curator at the New York State Museum. Evidence points to an explosion that occurred in the Cambrian period, which led to a rapid rate of evolution and mass extinction of many species.
"By process of elimination, primary causes of mass extinctions are linked in various ways to the carbon cycle in general and ocean chemistry in particular with clear association with atmospheric carbon dioxide levels," states a study, "Mass Extinctions and Ocean Acidification: Biological Constraints on Geological Dilemmas" by J. E. N. Veron.
On a similar note, "... the higher the level, the greater the risk that a vicious circle of global warming could be unleashed, inflicting potentially irreversible damage to Earth's climate system," reported Breitbart.
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