Navigation Links
Fossilized pollen reveals climate history of northern Antarctica
Date:6/27/2011

HOUSTON -- (June 27, 2011) -- A painstaking examination of the first direct and detailed climate record from the continental shelves surrounding Antarctica reveals that the last remnant of Antarctic vegetation existed in a tundra landscape on the continent's northern peninsula about 12 million years ago. The research, which was led by researchers at Rice University and Louisiana State University, appears online this week and will be featured on the cover of the July 12 issue of the Proceedings of the National Academy of Sciences.

The new study contains the most detailed reconstruction to date of the climatic history of the Antarctic Peninsula, which has warmed significantly in recent decades. The rapid decline of glaciers along the peninsula has led to widespread speculation about how the rest of the continent's ice sheets will react to rising global temperatures.

"The best way to predict future changes in the behavior of Antarctic ice sheets and their influence on climate is to understand their past," said Rice University marine geologist John Anderson, the study's lead author. The study paints the most detailed picture to date of how the Antarctic Peninsula first succumbed to ice during a prolonged period of global cooling.

In the warmest period in Earth's past 55 million years, Antarctica was ice-free and forested. The continent's vast ice sheets, which today contain more than two-thirds of Earth's freshwater, began forming about 38 million years ago. The Antarctic Peninsula, which juts farther north than the rest of the continent, was the last part of Antarctica to succumb to ice. It's also the part that has experienced the most dramatic warming in recent decades; its mean annual temperatures rose as much as six times faster than mean annual temperatures worldwide.

"There's a longstanding debate about how rapidly glaciation progressed in Antarctica," said Sophie Warny, a Louisiana State University geologist who specializes in palynology (the study of fossilized pollen and spores) and led the palynological reconstruction. "We found that the fossil record was unambiguous; glacial expansion in the Antarctic Peninsula was a long, gradual process that was influenced by atmospheric, tectonic and oceanographic changes."

Warny, her students and colleague Rosemary Askin were able to ascertain the exact species of plants that existed on the peninsula over the past 36 million years after a painstaking, three-year examination of thousands of individual grains of pollen that were preserved in muddy sediments beneath the sea floor just off the coast.

"The pollen record in the sedimentary layers was beautiful, both in its richness and depth," Warny said. "It allowed us to construct a detailed picture of the rapid decline of the forests during the late Eocene -- about 35 million years ago -- and the widespread glaciation that took place in the middle Miocene -- about 13 million years ago."

Obtaining the sedimentary samples wasn't easy. The muddy treasure trove was locked away beneath almost 100 feet of dense sedimentary rock. It was also off the coast of the peninsula in shallow waters that are covered by ice most of the year and beset by icebergs the rest. Anderson, a veteran of more than 25 research expeditions to Antarctica, and colleagues spent more than a decade building a case for the funding to outfit an icebreaker with the right kind of drilling equipment to bore through the rock.

In 2002, the National Science Foundation (NSF) funded the project, which was dubbed SHALDRIL. Three years later, the NSF research vessel Nathaniel B. Palmer left on the first of two drilling cruises.

"It was the worst ice year that any of us could remember," Anderson said. "We'd spend most of a day lowering drill string to the ocean floor only to pull it back up to get out of the way of approaching icebergs."

The next year was little better, but the SHALDRIL team managed to obtain enough core samples to cover the past 36 million years, thanks to the logistical planning of marine geologist Julia Wellner and to the skill of the drilling crew. By end of the second season, Anderson said, the crew could drill as much as a meter every five minutes.

Reconstructing a detailed climate record from the sample was another Herculean task. In addition to the three-year palynological analysis at LSU, University of Southampton palaeoceanographer Steven Bohaty led an effort to nail down the precise age of the various sediments in each core sample. Wellner, now at the University of Houston, examined the characteristics of the sediments to determine whether they formed below an ice sheet, in open marine conditions or in a combined glacial-marine setting. Other members of the team had to count, categorize and even examine the surface texture of thousands of sand grains that were preserved in the sediments. Gradually, the team was able to piece together a history of how much of the peninsula was covered by glaciers throughout the past 36 million years.

"SHALDRIL gave us the first reliable age constraints on the timing of ice sheet advance across the northern peninsula," Anderson said. "The rich mosaic of organic and geologic material that we found in the sedimentary record has given us a much clearer picture of the climatic history of the Antarctic Peninsula. This type of record is invaluable as we struggle to place in context the rapid changes that we see taking place in the peninsula today."


'/>"/>

Contact: Jade Boyd
jadeboyd@rice.edu
713-348-6778
Rice University
Source:Eurekalert  

Related biology news :

1. Ancient DNA, not fossilized bones, shows late survival of Ice Age megafauna
2. Worlds largest snake discovered in fossilized rainforest
3. Pollen also appears outside flowering season
4. UF Pine lsland pollen study leads to revision of states ancient geography
5. Amount of dust, pollen matters for cloud precipitation, climate change
6. Gone with the wind: Far-flung pine pollen still potent miles from the tree
7. Algae and pollen grains provide evidence of remarkably warm period in Antarcticas history
8. Exeter study reveals US turtles movements
9. New research on community gardening reveals the roots of emotional and physical health
10. Landmark report reveals immense burden of osteoporotic fractures in Europe
11. Study reveals important aspects of signaling across cell membranes in plants
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Fossilized pollen reveals climate history of northern Antarctica
(Date:3/23/2017)... DUBLIN , Mar. 23, 2017 Research ... Anti-Theft System Market Analysis & Trends - Industry Forecast to 2025" ... ... to grow at a CAGR of around 8.8% over the next ... This industry report analyzes the market estimates and forecasts for all ...
(Date:3/20/2017)... At this year,s CeBIT Chancellor Dr. Angela Merkel visited ... to the DERMALOG stand together with the Japanese Prime Minster Shinzo Abe. ... the largest German biometrics company the two government leaders could see the ... well as DERMALOG´s multi-biometrics system.   Continue Reading ... ...
(Date:3/9/2017)... Australia , March 9, 2017 /PRNewswire/ ... at the prestigious World Lung Imaging Workshop at the ... Fouras , was invited to deliver the latest data ... This globally recognised event brings together leaders at the ... latest developments in lung imaging. "The ...
Breaking Biology News(10 mins):
(Date:4/26/2017)... ... April 25, 2017 , ... LABS, Inc. (LABS) announced in December 2016 ... extensive test menu: Nucleic Acid Testing (NAT) for ZIKV; and Enzyme Immunoassays (EIAs) specific ... offer NAT screening for blood donors under an Investigational New Drug (IND) study protocol. ...
(Date:4/26/2017)... Pa. , April 26, 2017  Genisphere ... delivery platform, has signed a collaborative and sponsored ... Dr. Silvia Muro . The overall goal ... and pharmacodynamics of various 3DNA designs and formulations ... involve targeting diseases of the vasculature as well ...
(Date:4/25/2017)... Providence -based biotechnology ... technology to an undisclosed global pharmaceutical company, for ... Tregitopes, pronounced T·rej·itopes, are a set of peptides ... Annie De Groot and EpiVax CIO ... autoimmune disease therapy, Tregitopes are capable of engaging regulatory ...
(Date:4/24/2017)... ... April 24, 2017 , ... ... denaturation in a cellular milieu; however, the broad application of this cellular target ... platforms with sensitive quantitative readouts. Cell-based thermal stabilization assays are valuable methods for ...
Breaking Biology Technology: