Santa Cruz CA (SPX) Dec 15, 2010
Deep sediment cores retrieved from the Bering Sea floor indicate that the region was ice-free all year and biological productivity was high during the last major warm period in Earth's climate history.
Christina Ravelo, professor of ocean sciences at the University of California, Santa Cruz, will present the new findings in a talk on December 13 at the fall meeting of the American Geophysical Union (AGU) in San Francisco.
Ravelo and co-chief scientist Kozo Takahashi of Kyushu University, Japan, led a nine-week expedition of the Integrated Ocean Drilling Program (IODP) to the Bering Sea last summer aboard the research vessel JOIDES Resolution. The researchers drilled down 700 meters through rock and sludge to retrieve sediments deposited during the Pliocene Warm Period, 3.5 to 4.5 million years ago.
"Evidence from the Pliocene Warm Period is relevant to studies of current climate change because it was the last time in our Earth's history when global temperatures were higher than today," Ravelo said.
Carbon dioxide levels during the Pliocene Warm Period were also comparable to levels today, and average temperatures were a few degrees higher, she said. Climate scientists are interested in what this period may tell us about the effects of global warming, particularly in the polar regions.
Current observations show more rapid warming in the Arctic compared to other places on Earth and compared to what was expected based on global climate models.
Ravelo's team found evidence of similar amplified warming at the poles during the Pliocene Warm Period. Analysis of the sediment samples indicated that average sea surface temperatures in the Bering Sea were at least 5 degrees Celsius warmer than today, while average global temperatures were only 3 degrees warmer than today.
Samples from the expedition showed evidence of consistently high biological productivity in the Bering Sea throughout the past five million years.
The sediments contain fossils of plankton, such as diatoms, that suggest a robust ecology of organisms persisting from the start of the Pliocene Warm Period to the present. In addition, samples from the Pliocene Warm Period include deep-water organisms that require more oxygenated conditions than exist today, suggesting that the mixing of water layers in the Bering Sea was greater than it is now, Ravelo said.
"We usually think of the ocean as being more stratified during warm periods, with less vertical movement in the water column," she said. "If the ocean was actually overturning more during a period when it was warmer than today, then we may need to change our thinking about ocean circulation."
today, the Bering Sea is ice-free only during the summer, but the sediment samples indicate it was ice-free year-round during the Pliocene Warm Period.
According to Ravelo, the samples showed no evidence of the pebbles and other debris that ice floes carry from the land out to sea and deposit on the seafloor as they melt. In addition, the researchers didn't find any of the microorganisms typically associated with sea ice, she said.
"The information we found tells us quite a bit about what things were like during the last period of global warming. It should benefit the scientists today who are sorting out how ocean circulation and conditions at the poles change as the Earth warms," Ravelo said.
Share This Article With Planet Earth
University of California - Santa Cruz
Beyond the Ice Age
It's Time For Europe To Step Up Research In The Polar Regions
Brussels, Belgium (SPX) Dec 10, 2010
Polar research must become an integral part of the European Union's research activities if Europe is to benefit from the dramatically changing face of the Polar Regions, the European Polar Board (EPB) said at the launch of its strategic position paper on European polar research: "Relevance, Strategic Context and Setting Future Directions." European research activities in the Polar Regions ... read more
Caricom-Australia chide empty promises to Haiti|
Tearful homecoming for Pakistan flood survivors
Clinton attacks slow Haiti quake progress
Clinton Haiti meeting moved due to unrest
Berkeley Researchers Discover Mobius Symmetry In Metamaterials
New Google TV sets facing delays: reports
'iCrime' wave fuelled by insatiable appetite for smartphones
Japan telecom firm KDDI to start e-book distribution
Storms leave 47 sailors missing, six dead: Vietnam officials
Tasmanian Scientists Expand Their View of The ocean
New Zealand feared China was destabilising Pacific: report
US gets tough on shark fins
Bering Sea Was Ice-Free And Full Of Life During Last Warm Period
Arctic Sea Ice Greenhouse Gases And Polar Bear Habitat
Arctic icecap safe from runaway melting: study
Russia plans annual arctic conferences
Bioethics Commission Calls For Enhanced Federal oversight In Field of Synthetic Biology
Chavez, farmers square off over land seizure
Australians buy cows and sheep with a mouse
Goji Berries Have A Significant Placebo Effect
Western US sloshes through epic rain, snows
Iran quake kills seven, wrecks villages
Volcano in Guatemala rumbling
Colombia faces rising death toll in floods
China not opposed to Sudan leader's arrest: WikiLeaks
Frontline Ivory Coast town fears new civil war
Interim leader urges army must back new Guinea president
Gambia denies it was intended recipient of Iran arms
Beetroot Juice Could Help People Live More Active Lives
Researchers Discover Compound With Potent Effects on Biological Clock
Our Flawed Understanding of Risk Helps Drive Financial Market Instability
Researchers Discover Compound With Potent Effects On Biological Clock
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2010 - SpaceDaily. AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement|