Featured Research

from universities, journals, and other organizations

Ice Sheet Behavior Much More Volatile And Dynamic Than Previously Thought, Tahiti Corals Show

Date:
April 30, 2009
Source:
University of Oxford
Summary:
Fossilized corals from tropical Tahiti show that the behavior of ice sheets is much more volatile and dynamic than previously thought, scientists have found.

The drilling platform researchers used in Tahiti to extract cores of fossilised coral from beneath the ocean floor.
Credit: Image courtesy of University of Oxford

Fossilised corals from tropical Tahiti show that the behaviour of ice sheets is much more volatile and dynamic than previously thought, a team led by Oxford University scientists has found.

Analysis of the corals suggests that ice sheets can change rapidly over just hundreds of years – events associated with sea level rises of several metres over the same period. It also shows that a natural warming mechanism thought to be responsible for ending ice ages does not fit the timing of the end of the penultimate ice age, around 137,000 years ago.

A report of the research appears online in the journal Science on April 23.

"It’s amazing just how rapidly these ‘melting’ – or ‘deglaciation’ – events occurred and how enormous the volumes of ice involved were," said Dr Alex Thomas, from the Department of Earth Sciences at Oxford University, lead author of the paper. "In the case of deglaciation after the penultimate ice age, before 137,000 years ago, we’re talking about ice sheets – that covered most of the USA and Canada and were up to five kilometres thick – simply vanishing."

The tropical paradise of Tahiti is an ideal place to study the sea level rises associated with deglaciation. This is because not only is it home to different species of corals that like to live at different depths but it is sinking at a constant rate which can be adjusted for when dating these corals, and it is far enough away from the ice sheets not to be affected by displacement or gravitational effects.

"Getting to these ancient fossilised corals without damaging the reef and local ocean life is far from easy," said Dr Thomas. "A robot submersible was sent to survey the ocean floor and placed a target which was used to guide down a drill from a shallow-draft drilling vessel with great precision and extract our cores. We only left a tiny hole behind that soon disappeared – something that was only possible because of the expertise of the Integrated Ocean Drilling Programme."

The fossilised coral within the cores showing sea level changes was then dated using a uranium dating technique. The timing of these changes showed that a natural warming mechanism known as northern hemisphere summer insolation could not have caused the deglaciation that brought the penultimate ice age to an end.

Dr Thomas said: "People had assumed that because this natural warming mechanism matched the timing of deglaciation ending the last ice age (around 21,000 years ago) that it would be responsible for the one before that. What we have shown is that this was not the case. We are starting to understand that recent observations of changes in ice sheets have not prepared us for just how rapidly the covering of ice across the Earth can fluctuate and that, as yet, we have not identified all the natural phenomena which drive deglaciation."


Story Source:

The above story is based on materials provided by University of Oxford. Note: Materials may be edited for content and length.


Journal Reference:

  1. Alex L. Thomas, Gideon M. Henderson, Pierre Deschamps, Yusuke Yokoyama, Andrew J. Mason, Edouard Bard, Bruno Hamelin, Nicolas Durand, and Gilbert Camoin. Penultimate Deglacial Sea-Level Timing from U/Th Dating of Tahitian Corals. Science, 2009; DOI: 10.1126/science.1168754

Cite This Page:

University of Oxford. "Ice Sheet Behavior Much More Volatile And Dynamic Than Previously Thought, Tahiti Corals Show." ScienceDaily. ScienceDaily, 30 April 2009. <www.sciencedaily.com/releases/2009/04/090423205104.htm>.
University of Oxford. (2009, April 30). Ice Sheet Behavior Much More Volatile And Dynamic Than Previously Thought, Tahiti Corals Show. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2009/04/090423205104.htm
University of Oxford. "Ice Sheet Behavior Much More Volatile And Dynamic Than Previously Thought, Tahiti Corals Show." ScienceDaily. www.sciencedaily.com/releases/2009/04/090423205104.htm (accessed July 28, 2014).

Share This




More Earth & Climate News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Sea Turtle Hatchlings Emerge from Nest

Raw: Sea Turtle Hatchlings Emerge from Nest

AP (July 27, 2014) A live-streaming webcam catches loggerhead sea turtle hatchlings emerging from a nest in the Florida Keys. (July 27) Video provided by AP
Powered by NewsLook.com
Trees Could Save More Than 850 Lives Each Year

Trees Could Save More Than 850 Lives Each Year

Newsy (July 27, 2014) A national study conducted by the USDA Forest Service found that trees collectively save more than 850 lives on an annual basis. Video provided by Newsy
Powered by NewsLook.com
Phoenix Thunderstorm Creates Giant Wall of Dust

Phoenix Thunderstorm Creates Giant Wall of Dust

Reuters - US Online Video (July 26, 2014) A giant wall of dust slowly moves north over the Phoenix area after a summer monsoon thunderstorm. Mana Rabiee reports. Video provided by Reuters
Powered by NewsLook.com
Rare Lemur Among Baby Animals Debuted at Cleveland Zoo

Rare Lemur Among Baby Animals Debuted at Cleveland Zoo

Reuters - US Online Video (July 26, 2014) A rare baby Lemur is among several baby animals getting their public debut at a Cleveland zoo. Mana Rabiee reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins