Fossil wood gives vital clues to ancient climates

Feb 23, 2006

New research into a missing link in climatology shows that the Earth was not overcome by a greenhouse period when dinosaurs dominated, but experienced rapid fluctuations in temperature and sea level change that resulted in a balance of the global carbon cycle. The study is being published in the March issue of Geology.

"Most people think the mid-Cretaceous period was a super-greenhouse," says Darren Gröcke, assistant professor and Director of the Stable Isotope Biogeochemistry Laboratory at McMaster University. "But in fact it was not to dissimilar to the climates over the past 5 million years."

By using high-resolution stable-isotope analysis from 95-million-year-old fossilized wood collected from Nebraska, Gröcke and his team were able to precisely correlate the terrestrial carbon cycle with that from deep-sea records. However, when they compared the carbon curves from both records, it was evident that a chunk of about 500,000 years was missing from the terrestrial record. Other records already indicated a drop in sea level, a 2-4ºC drop in oceanic temperature and a breakdown in oceanic stratification coincident with a marine extinction event.

"Rapid, large falls in sea-level in the ancient record are typically only produced by a glaciation, and so the combination of all the data during the mid-Cretaceous period suggests a short-lived glaciation during a period generally considered to be a super-greenhouse," says Gröcke.

"Whatever hits the water causes a ripple effect on land," says Gröcke. "Earth often undergoes rapid temperature fluctuations, and this new information may help us to understand how the biosphere will respond to human-generated alterations of CO2 concentration."

He said the research not only challenges conventional wisdom surrounding ancient climates, it makes a case for the use of high-resolution sampling in order to reconstruct a more accurate picture of the ancient climate and its affect on the Earth.

Source: McMaster University

Explore further: POLARBEAR detects curls in the universe's oldest light

add to favorites email to friend print save as pdf

Related Stories

Recommended for you

China to send orbiter to moon and back

2 hours ago

China will launch its latest lunar orbiter in the coming days, state media said Wednesday, in its first attempt to send a spacecraft around the moon and back to Earth.

NASA Webb's heart survives deep freeze test

13 hours ago

After 116 days of being subjected to extremely frigid temperatures like that in space, the heart of the James Webb Space Telescope, the Integrated Science Instrument Module (ISIM) and its sensitive instruments, ...

Cosmic rays threaten future deep-space astronaut missions

17 hours ago

Crewed missions to Mars remain an essential goal for NASA, but scientists are only now beginning to understand and characterize the radiation hazards that could make such ventures risky, concludes a new paper ...

User comments : 0