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Has the mystery of the Antarctic ice sheet been solved?
February 28, 2008New evidence could solve the puzzle of why Antarctica went into the deep freeze
A team of scientists from Cardiff University's School of Earth and Ocean Sciences and Amgueddfa Cymru - National Museum Wales travelled to Africa to find new evidence of climate change which helps explain some of the mystery surrounding the appearance of the Antarctic ice sheet.
Ice sheet formation in the Antarctic is one of the most important climatic shifts in Earth's history. However, previous temperature records show no evidence of the oceans cooling at this time, but instead suggest they actually warmed, presenting a confusing picture of the climate system which has long been a mystery in palaeoclimatology.
Now Dr Carrie Lear, Lecturer in Palaeoceanography, and her team at Cardiff have presented new temperature records using ancient sea floor mud recovered from Tanzania, East Africa. The shell chemistry of pin-head sized animals called foraminifera ("forams") reveal that ocean temperatures did in fact cool by about 2.50C.
Dr Lear said: "Forams are great tools for studying climates of the past, which helps us learn about the uncertainties of our future greenhouse climate. These new records help resolve a long-standing puzzle regarding the extent of ice-sheet growth versus global cooling, and bring climate proxy records into line with climate model simulations.
"We have been able to use the chemistry of the Tanzanian microfossils to construct records of temperature and ice volume over the interval of the big climate switch. These new records show that the world's oceans did cool during the growth of an ice sheet, and that the volume of ice would have fitted onto Antarctica; so now the computer models of climate and the past climate data match up."
The team at Cardiff University's School of Earth, Ocean and Planetary Sciences will now look for evidence of the ultimate cause of the global cooling using the forams. They believe the prime suspect is a gradual reduction of CO2 in the atmosphere, combined with a 'trigger' time when Earth's orbit around the sun made Antarctic summers cold enough for ice to remain frozen all year round.
Cardiff University
Now Dr Carrie Lear, Lecturer in Palaeoceanography, and her team at Cardiff have presented new temperature records using ancient sea floor mud recovered from Tanzania, East Africa. The shell chemistry of pin-head sized animals called foraminifera ("forams") reveal that ocean temperatures did in fact cool by about 2.50C.
Dr Lear said: "Forams are great tools for studying climates of the past, which helps us learn about the uncertainties of our future greenhouse climate. These new records help resolve a long-standing puzzle regarding the extent of ice-sheet growth versus global cooling, and bring climate proxy records into line with climate model simulations.
"We have been able to use the chemistry of the Tanzanian microfossils to construct records of temperature and ice volume over the interval of the big climate switch. These new records show that the world's oceans did cool during the growth of an ice sheet, and that the volume of ice would have fitted onto Antarctica; so now the computer models of climate and the past climate data match up."
The team at Cardiff University's School of Earth, Ocean and Planetary Sciences will now look for evidence of the ultimate cause of the global cooling using the forams. They believe the prime suspect is a gradual reduction of CO2 in the atmosphere, combined with a 'trigger' time when Earth's orbit around the sun made Antarctic summers cold enough for ice to remain frozen all year round.
Cardiff University
Ice Sheet Current Events and Ice Sheet News RSSNorth Carolina sea levels rising 3 times faster than in previous 500 years, Penn study says
An international team of environmental scientists led by the University of Pennsylvania has shown that sea-level rise, at least in North Carolina, is accelerating.
Queen's scientists on international team discover 'ecologically unique' changes in Arctic lake
Queen's University biologists are part of an international research team whose discovery of a rare sediment core in a remote Arctic lake provides compelling evidence of unprecedented environmental changes occurring over the past few decades.
West Antarctic ice sheet may not be losing ice as fast as once thought
New ground measurements made by the West Antarctic GPS Network (WAGN) project, composed of researchers from The University of Texas at Austin, The Ohio State University, and The University of Memphis, suggest the rate of ice loss of the West Antarctic ice sheet has been slightly overestimated.
Last time carbon dioxide levels were this high: 15 million years ago, scientists report
You would have to go back at least 15 million years to find carbon dioxide levels on Earth as high as they are today, a UCLA scientist and colleagues report Oct. 8 in the online edition of the journal Science.
NASA flies to Antarctica for largest airborne polar ice survey
NASA begins a series of flights Oct. 15 to study changes to Antarctica's sea ice, glaciers and ice sheets. The flights are part of Operation Ice Bridge, a six-year campaign that is the largest airborne survey ever made of ice at Earth's polar regions.
New coastland map could help strengthen sea defenses
The 'Coastland Map' produced by scientists from Durham University and published in the Journal GSA Today, charts the post Ice-Age tilt of the UK and Ireland and current relative sea-level changes.
Algae and pollen grains provide evidence of remarkably warm period in Antarctica's history
For Sophie Warny, LSU assistant professor of geology and geophysics and curator at the LSU Museum of Natural Science, years of patience in analyzing Antarctic samples with low fossil recovery finally led to a scientific breakthrough.
Egg-shaped legacy of Britain's mobile ice-sheet
The ice sheets that sculpted the landscape of northern Britain moved in unexpected ways and left distinctive egg-shaped features according to new research.
New CO2 data helps unlock the secrets of Antarctic formation
The link between declining CO2 levels in the earth's atmosphere and the formation of the Antarctic ice caps some 34 million years ago has been confirmed for the first time in a major research study.
Map characterizes active lakes below Antarctic ice
Lakes in Antarctica, concealed under miles of ice, require scientists to come up with creative ways to identify and analyze these hidden features.
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