Giant volcanic eruption drove historic global warming event
8 Dec 2017 by qwwqdccwwm.d qwwqdccwwm.d
New research by a group of international scientists suggests that an extreme global warming event 56 million years ago was caused by a huge volcanic eruption
New research by a group of international scientists suggests that an extreme global warming event 56 million years ago was caused by a huge volcanic eruption.
Using a combination of novel geochemical measurements and global climate modelling, the researchers were able to show atmospheric CO2 more than doubled in less than 25 thousand years. This occurred during the Palaeocene-Eocene Thermal Maximum (PETM) and was caused solely by volcanoes.
Dr Marcus Gutjahr, who led the study while at the University of Southampton, said: “In order to identify the source of carbon we first generated a new record of the change in ocean pH through the PETM, by measuring changes in the balance of isotopes of the element boron in ancient marine fossils called foraminifera."
The PETM was the most rapid and extreme natural global warming event to occur on Earth in the past 66 million years. It lasted for 150 thousand years with global temperatures increasing by at least 5°C during this period of time. While the PETM event is thought to have been caused by an injection of carbon into the ocean and atmosphere there are a number of unknowns. These include what triggered this, where the carbon originated and the total amount released.
During the PETM massive flood basalts formed large stretches of ocean floor and continents, coated in lava. These occurred as Greenland and North America began separating from north-western Europe, creating the North Atlantic Ocean. More than 12,000 petagrams of carbon was associated with the PETM from a predominantly carbon source. The scientists’ computer simulations suggests that atmospheric CO2 increased from 850 parts per million to above 2000 ppm.
Professor Andy Ridgwell from the University of California, said: “Ocean pH tells us about the amount of carbon absorbed by ancient seawater, but we can get even more information by also considering changes in the isotopes of carbon, as these provide an indication of its source. When we force a numerical global climate model to take into account both sets of changes, the results point to the large-scale volcanism associated with the opening of the North Atlantic as the primary driver of the PETM."
The paper Very large release of mostly volcanic carbon during the Paleocene-Eocene Thermal Maximum is published in Nature.
