Lead author Hubertus Fischer, an experimental climate physics professor at the University of Bern in Switzerland, said that ice cores contain little air bubbles and, thus, represent the only direct archive of the composition of the past atmosphere.
A 3.2-km-long ice core drilled almost a decade ago at Dome Concordia (Dome C) in Antarctica revealed 800,000 years of climate history, showing that greenhouse gases and temperature have mostly moved in lockstep.
Now, an international team of scientists wants to know what happened before that.
At the root of their quest is a climate transition that marine-sediment studies reveal happened some 1.2 million years to 900,000 years ago.
Fischer said that the Mid Pleistocene Transition is a most important and enigmatic time interval in the more recent climate history of our planet.
The Earth's climate naturally varies between times of warming and periods of extreme cooling (ice ages) over thousands of years. Before the transition, the period of variation was about 41 thousand years while afterwards it became 100 thousand years.
Climate scientists suspect greenhouse gases played a role in forcing this transition, but they need to drill into the ice to confirm their suspicions. "The information on greenhouse-gas concentrations at that time can only be gained from an Antarctic ice core covering the last 1.5 million years. Such an ice core does not exist yet, but ice of that age should be in principle hidden in the Antarctic ice sheet."
The study results have been published in journal Climate of the Past.
--ANI (Posted on 06-11-2013)