Tag Archives: AGU

From Distant Past, Lessons on Ocean Acidification

First posted Dec. 8, 2011 on the Earth Institute’s State of the Planet blog.

foraminifera, Paleocene-Eocene Thermal Maximum, extinction

A core section shows shells of foraminifera, and reduced carbonate preservation, at the Paleocene-Eocene Thermal Maximum. During the period, researchers believe up to half of deep-sea benthic foraminifer species suffered extinction. Photo: Laura Foster, University of Bristol

Oceans turned more acidic during a period of great warming some 56 million years ago, leading to an extinction of bottom-dwelling marine species known as foraminifera, a scenario that could be repeated as a result of human-induced global warming today, only much more quickly.

To better understand what could happen in the near future, geochemist Bärbel Hönisch of the Lamont-Doherty Earth Observatory and a few colleagues studied ocean acidity events over the past 250 million years to confirm whether acidification took place during periods of global warming. The conditions of one period in particular – the Paleocene-Eocene Thermal Maximum — were similar to the worst-case scenarios scientists project for future climate change.

“The earlier changes affected the biology, so we’d expect that would happen today,” Hönisch said. She doesn’t like to speculate on precisely what the impact might be; some creatures may disappear, others may adapt.

“I don’t think it will destroy the earth — the earth will cope with us,” she said. “We may not like what happens.” Hönisch gave a talk on her research today at the fall meeting of the American Geophysical Union in San Francisco, as part of a broader discussion there of findings related to ocean acidification.

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Where Continents Divide, and Rocks Rise from the Deep

First posted Dec. 6, 2011 on the Earth Institute’s State of the Planet blog.

Papua New Guinea, seismometer, earthquakes

A typical seismometer installation on Goodenough Island, Papua New Guinea, from an earlier expedition in 1999. Photo: CDPapua project.

Along the Woodlark Rift, a long break in the earth’s crust in eastern Papua New Guinea, continents are breaking apart, “like a snake opening its mouth.” Geologic processes that are still a mystery are actively stretching the crust and pushing huge masses of rock, formed under immense pressures as deep as 100 kilometers below, to the surface. Offshore, the ocean floor is spreading.

The setting offers a unique opportunity for scientists to study the powerful forces reshaping the surface of the earth, responsible for the movement of continents and creation of oceans.

Papua New Guinea, seismometers, earthquakes

Map shows locations of seismometers deployed to study movements of the earth around eastern Papua New Guinea. Image: CDPapua project.

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