Scientists Confirm Link between Volcanic Activity and Ancient Warming Event

Scientists suggest gasses released during heavy volcanic activity may have triggered the Paleocene-Eocene thermal maximum, a period of climate change marked by a rise in global temperatures and massive marine die-offs, according to research in the 27 April issue of Science.

The findings may help to shed light on how human-caused greenhouse gasses may affect Earth's most sensitive climates.

In their article, Michael Storey, director of the Quaternary Dating Laboratory at Roskilde University in Denmark, and his colleagues wrote that approximately 55 million years ago, the oceans experienced a sharp increase in temperature and acidity, greatly affecting the life that lived in it.

"During the Paleocene-Eocene thermal maximum, the sea surface temperature rose by 5°C in the tropics and more than 6°C in the Arctic, in conjunction with ocean acidification and the extinction of 30 to 50% of deep-sea benthic foraminiferal species," wrote Storey. Such species include tiny organisms living on the ocean bottom that form the base of the oceanic food web.

By examining the geologic record, the scientists discovered that the period was also marked by massive volcanic eruptions near Greenland and Europe, releasing huge volumes of ash and greenhouse gasses—either methane or carbon dioxide—into the atmosphere.

"The correlations support the view that the PETM [the Paleocene-Eocene thermal maximum] was triggered by greenhouse gas release during magma interaction with basin-filling carbon rich sedimentary rocks . . . between Greenland and Europe," wrote the authors.

Using chemical dating and chemical fingerprinting, the team also discovered that the ash found in East Greenland is similar to Atlantic Ocean floor sediment, a probable factor in ocean acidification.

The authors note that the scientific dating of the East Greenland and Atlantic Ocean floor rock indicates that they are roughly the same age. In addition, the chemicals found in both the ocean sediments and the East Greenland formations, which are relatively atypical for Atlantic Ocean rocks during the time period, suggest that they came from the same eruption event.

In addition to this article, other recent studies have documented the steady decline in the ocean health around the world.

Recently, a team of scientists from the U.S National Oceanic and Atmospheric Administration and the University of Washington surveying the Pacific Ocean found that the increase in temperature and acidity is decreasing the amount of dissolved oxygen and the building blocks for coral and some kinds of plankton.

Evelyn Brown and Benjamin Somers

26 April 2007