Researchers from the Oeschger Centre for Climate Change Research at the University of Bern reconstructed for the first mean ocean temperatures over the last 700,000 years using ice core data. The new knowledge serves to improve our understanding of the climate system.
Bern's ice core researchers were already able to demonstrate in 2008 how the concentration of CO2 in the atmosphere has changed over the past 800,000 years. Now, using the same ice core from the Antarctic, the group led by Bernese climate researcher Hubertus Fischer shows the maximum and minimum values between which the mean ocean temperature has fluctuated over the past 700,000 years.
The results of the reconstruction have just been published in the journal "Climate of the Past". The study's key findings: Mean ocean temperatures have been very similar over the last seven ice ages, averaging about 3.3 °C colder than the pre-industrial reference period, as already suggested by syntheses of deep water temperatures from marine sediments. However, ocean temperatures in the warm periods 450,000 years ago were much colder and CO2 concentrations were lower than in our present warm period, despite similar solar radiation. The new measurements show that ocean temperature is also shaped by changes in ocean circulation. The so-called global circulation of deep waters has a significant impact on heat storage in the ocean.
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