Eric Monnin

Stable carbon cycle-climate relationship during the Late Pleistocene.

A record of atmospheric carbon dioxide (CO2) concentrations measured on the EPICA (European Project for Ice Coring in Antarctica) Dome Concordia ice core extends the Vostok CO2 record back to 650,000 years before the present (yr B.P.). Before 430,000 yr B.P., partial pressure of atmospheric CO2 lies within the range of 260 and 180 parts per million by volume. This range is almost 30% smaller than that of the last four glacial cycles; however, the apparent sensitivity between deuterium and CO2 remains stable throughout the six glacial cycles, suggesting that the relationship between CO2 and Antarctic climate remained rather constant over this interval.

Atmospheric CO2 concentration from 60 to 20 kyr BP from the Taylor Dome Ice Core, Antarctica

A high-resolution record of the atmospheric CO2 concentration from 60 to 20 thousand years before present (kyr BP) based on measurements on the ice core of Taylor Dome, Antarctica is presented. This record shows four distinct peaks of 20 parts per million by volume (ppmv) on a millennial time scale. Good correlation of the CO2 record with temperature reconstructions based on stable isotope measurements on the Vostok ice core (Antarctica) is found.

Atmospheric CO2, CH4 and N2O records over the past 60 000 years based on the comparison of different polar ice cores

Abstract Analyses of air extracted from polar ice cores are the most straightforward method of reconstructing the atmospheric concentrations of greenhouse gases and their variations for past climatic epochs. These measurements show that the concentration of the three most important greenhouse gases (other than water vapour) CO2, CH4 and N2O have steadily increased during the past 250 years due to anthropogenic activities (Prather and others, 2001; Prentice and others, 2001). Ice-core results also provided the first evidence of a substantial increase in the concentration of the three gases during the transition from the last glacial epoch to the Holocene (Raynaud and others, 1993). However, results from different cores are not always in agreement concerning details and small, short-term variations. the composition of the air enclosed in bubbles can be slightly changed by fractionation during the enclosure process, by chemical reactions and/or biological activity in the ice and by fractionation during the air extraction. We compile here several records with short-term variations or anomalies and discuss possible causes, taking into account improved analytical techniques and new results.

Modeling past atmospheric CO2: Results of a challenge

The models and concepts used to predict future climate are based on physical laws and information obtained from observations of the past. New paleoclimate records are crucial for a test of our current understanding. The Vostok ice core record [Petit et al., 1999] showed that over the past 420 kyr (1 kyr = 1000 years), Antarctic climate and concentrations of the greenhouse gases carbon dioxide (CO2) and methane (CH4) were tightly coupled. In particular, CO2 seemed to be confined between bounds of about 180 ppmv (parts per million by volume) in glacial periods and 280 ppmv in interglacials; both gases rose and fell with climate as the Earth passed through four glacial/interglacial cycles.