|
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 News and Current Ice Sheet Events RSSUnravelling the 'inconvenient truth' of glacier movement
Predicting climate change depends on many factors not properly included in current forecasting models, such as how the major polar ice caps will move in the event of melting around their edges.
Greenland ice core analysis shows drastic climate change near end of last ice age
Information gleaned from a Greenland ice core by an international science team shows that two huge Northern Hemisphere temperature spikes prior to the close of the last ice age some 11,500 years ago were tied to fundamental shifts in atmospheric circulation.
Data show Antarctic ice stream radiating seismically
A seismologist at Washington University in St. Louis and colleagues at Pennsylvania State University and Newcastle University in the United Kingdom have found seismic signals from a giant river of ice in Antarctica that makes California's earthquake problem seem trivial.
Scientists endure Arctic for last campaign prior to CryoSat-2 launch
An international group of scientists has swapped their comfortable offices for one of the most inhospitable environments on the planet to carry out a challenging field campaign that is seen as the key to ensuring the data delivered by ESA's ice mission CryoSat will be as accurate as possible.
Climate Models Overheat Antarctica, New Study Finds
Computer analyses of global climate have consistently overstated warming in Antarctica, concludes new research by scientists at the National Center for Atmospheric Research (NCAR) and Ohio State University.
'New' ancient Antarctic sediment reveals climate change history
Recent additions to the premier collection of Southern Ocean sediment cores at Florida State University's Antarctic Marine Geology Research Facility will give international scientists a close-up look at fluctuations that occurred in Antarctica's ice sheet and marine and terrestrial life as the climate cooled considerably between 20 and 14 million years ago.
Researchers warm up to melt's role in Greenland ice loss
In July 2006, researchers afloat in a dinghy on a mile-wide glacial lake in Greenland studied features of the lake and ice 40 feet below. Ten days later the entire contents of the lake emptied through a crack in the ice with a force equaling the pummeling water of Niagara Falls. The entire process only took 90 minutes.
Greenland's rising air temperatures drive ice loss at surface and beyond
A new NASA study confirms that the surface temperature of Greenland's massive ice sheet has been rising, stoked by warming air temperatures, and fueling loss of the island's ice at the surface and throughout the mass beneath.
UNH-NOAA ocean mapping expedition yields new insights into arctic depths
New Arctic sea floor data released today by the University of New Hampshire and the National Oceanic and Atmospheric Administration suggests that the foot of the continental slope off Alaska is more than 100 nautical miles farther from the U.S. coast than previously assumed.
New Greenland Ice Sheet Data Will Impact Climate Change Models
A comprehensive new study authored by University at Buffalo scientists and their colleagues for the first time documents in detail the dynamics of parts of Greenland's ice sheet, important data that have long been missing from the ice sheet models on which projections about sea level rise and global warming are based.
More Ice Sheet News Articles
| © 2008 BrightSurf.com |