R. Wordsworth: Department of the Geophysical Sciences, University of Chicago, Chicago, Illinois.
4. Updated ice core record captures Industrial Era carbon variability
In 1999, researchers published data from ice cores collected at Law Dome, a research site in East Antarctica. These data are distinguished by their high time resolution, and by their overlap with modern measurements, providing one of the most important records of how the atmosphere's chemical composition changed over the past 1000 years. Air trapped in bubbles in the ice core let researchers measure the concentration of carbon dioxide and other gases, and analyze the ratio of carbon-13 to carbon-12 isotopes in the atmospheric carbon dioxide. Fossil fuel burning releases carbon dioxide that is depleted in carbon-13 isotopes, and the Law Dome record provided evidence that modern increases in atmospheric carbon dioxide are due to anthropogenic activity. In their new study, Rubino et al., a team that includes some of the authors from that original analysis, use novel tools and techniques to update their ice core record.
The shallowest portions of the Law Dome core contain air which overlaps in age with direct marine boundary layer samples collected since 1978 in Cape Grim, Tasmania, and with samples collected from firn at Law Dome and at the South Pole, providing a bridge from paleoclimate measurements to direct modern observations. Firn is compressed snow that forms beneath the snow surface, and the air within it contains a record of recent atmospheric composition. Previous research had shown inconsistencies between the records of the carbon dioxide isotope ratio derived from these various locations. However, using modern techniques to reanalyze ice core and firn samples that were previously collected, the authors find that the records of atmospheric carbon dioxide i
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American Geophysical Union