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Paleo Study: CO2 Risk To Antarctica Worse Than Thought

25.02.2016
25.02.2016 15:43 Age: 1 year

Atmospheric carbon dioxide concentrations 16 million years ago were similar to those seen today but temperatures were warmer and ocean levels were much higher. Two new studies of conditions in Antarctica at that time using data from the ANDRILL project suggest that today's Antarctic ice sheets could be more vulnerable to carbon dioxide than thought

Click to enlarge. The historic record suggests Antartica's ice sheets ae at a greater risk of melting than had been thought, acording to researchers. Courtesy: Ralph Timmermann and the Alfred Wegener Institute

 

We present two news releases - one from the University of California, Los Angeles and one from the University of Massachusets at Amherst - summarising new research reported in two papers in the Proceedings of the National Academy of Sciences.

Here is the news release from the University of California, Los Angeles:

Antarctica could be headed for major meltdown

UCLA geochemist finds striking similarities between climate change patterns today and millions of years ago

by David Colgan, University of California, Los AngelesEnd of UCLA news release.

Here is the University of Massachusetts at Amherst news release:

Antarctic Ice Sheet is More Vulnerable to CO2 than Expected

UMass Amherst researchers, others assess Antarctic ice sheet variables and behavior

From the University of Massachusetts at Amherst2) reached levels like those expected to occur in about 30 years, plus sediment core findings reported in a companion paper, suggest that the ice sheets are more vulnerable to rising atmospheric CO2 222End of University of Massachusetts at Amherst news release

Significance

Antarctic ice sheet sensitivity to atmospheric CO2 variations in the early to mid-Miocene

PNAS reports the significance of this paper as follows: New information from the ANDRILL-2A drill core and a complementary ice sheet modeling study show that polar climate and Antarctic ice sheet (AIS) margins were highly dynamic during the early to mid-Miocene. Changes in extent of the AIS inferred by these studies suggest that high southern latitudes were sensitive to relatively small changes in atmospheric CO2 (between 280 and 500 ppm). Importantly, reconstructions through intervals of peak warmth indicate that the AIS retreated beyond its terrestrial margin under atmospheric CO2 conditions that were similar to those projected for the coming centuries.

Dynamic Antarctic ice sheet during the early to mid-Miocene

PNAS reports the significance of this paper as follows: Atmospheric concentrations of carbon dioxide are projected to exceed 500 ppm in the coming decades. It is likely that the last time such levels of atmospheric CO2 were reached was during the Miocene, for which there is geologic data for large-scale advance and retreat of the Antarctic ice sheet. Simulating Antarctic ice sheet retreat is something that ice sheet models have struggled to achieve because of a strong hysteresis effect. Here, a number of developments in our modeling approach mean that we are able to simulate large-scale variability of the Antarctic ice sheet for the first time. Our results are also consistent with a recently recovered sedimentological record from the Ross Sea presented in a companion article.

Abstracts

Antarctic ice sheet sensitivity to atmospheric CO2 variations in the early to mid-Miocene22 concentrations were at or below preindustrial levels (∼280 ppm). Five intervals reflect ice sheet minima and air temperatures warm enough for substantial ice mass loss during episodes of high (∼500 ppm) atmospheric CO2. These new drill core data and associated ice sheet modeling experiments indicate that polar climate and the AIS were highly sensitive to relatively small changes in atmospheric CO2 during the early to mid-Miocene.

Dynamic Antarctic ice sheet during the early to mid-Miocene

Geological data indicate that there were major variations in Antarctic ice sheet volume and extent during the early to mid-Miocene. Simulating such large-scale changes is problematic because of a strong hysteresis effect, which results in stability once the ice sheets have reached continental size. A relatively narrow range of atmospheric CO22 between 280 and 500 ppm and a changing astronomical configuration. This result represents a substantial advance in resolving the long-standing model data conflict of Miocene Antarctic ice sheet and sea level variability.

Citations

Antarctic ice sheet sensitivity to atmospheric CO2 variations in the early to mid-Miocene by Richard Levy, David Harwood, Fabio Florindo, Francesca Sangiorgi, Robert Tripati, Hilmar von Eynatten, Edward Gasson, Gerhard Kuhn, Aradhna Tripati, Robert DeConto, Christopher Fielding, Brad Field, Nicholas Golledge, Robert McKay, Timothy Naish, Matthew Olney, David Pollard, Stefan Schouten, Franco Talarico, Sophie Warny, Veronica Willmott, Gary Acton, Kurt Panter, Timothy Paulsen, Marco Taviani and the SMS Science Team published in the Proceedings of the National Academy of Sciences, doi: 10.1073/pnas.1516030113

Read the abstract and get the paper here.

Dynamic Antarctic ice sheet during the early to mid-Miocene by Edward Gasson, Robert M. DeContoa, David Pollar and Richard H. Levy published in the Proceedings of the National Academy of Sciences, doi:10.1073/pnas.1516130113

Read the abstract and get the paper here.

Sources

University of Massachusetts at Amherst news release here.

UCLA news release here.