ORCID Profile
0000-0002-1163-2818
Current Organisations
National Institute of Water and Atmospheric Research Wellington
,
NIWA - The National Institute of Water and Atmospheric Research Ltd.
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Publisher: American Association for the Advancement of Science (AAAS)
Date: 03-09-2010
Publisher: Springer Science and Business Media LLC
Date: 08-2017
DOI: 10.1038/NATURE23316
Abstract: Methane (CH
Publisher: Elsevier BV
Date: 03-2016
Publisher: Elsevier BV
Date: 03-2013
Publisher: Copernicus GmbH
Date: 28-02-2017
DOI: 10.5194/CP-2017-25
Abstract: Abstract. Old ice for paleo-environmental studies, traditionally accessed through deep core drilling on domes and ridges on the large ice sheets, can also be retrieved at the surface from ice sheet margins and blue ice areas. The practically unlimited amount of ice available at these sites satisfies a need in the community for studies of trace components requiring large s le volumes. For margin sites to be useful as ancient ice archives, the ice stratigraphy needs to be understood and age models need to be established. We present measurements of trapped gases in ice from Taylor Glacier, Antarctica, to date the ice and assess the completeness of the stratigraphic section. Using δ18O of O2 and methane concentrations, we unambiguously identify ice from the last glacial cycle, covering every climate interval from the early Holocene to the penultimate interglacial. A high-resolution transect reveals the last deglaciation and the Last Glacial Maximum (LGM) in detail. We observe large-scale deformation in the form of folding, but in idual stratigraphic layers do not appear to have undergone irregular thinning. Rather, it appears that the entire LGM-deglaciation sequence has been transported from the interior of the ice sheet to the surface of Taylor Glacier relatively undisturbed. We present an age model that builds the foundation for gas studies on Taylor Glacier. A comparison with the Taylor Dome ice core confirms that the section we studied on Taylor Glacier is better suited for paleo-climate reconstructions of the LGM due to higher accumulation rates.
Publisher: International Glaciological Society
Date: 2008
DOI: 10.3189/002214308784886135
Abstract: We present techniques for obtaining large (∼100 L STP) s les of ancient air for analysis of 14 C of methane ( 14 CH 4 )and other trace constituents. Paleoatmospheric 14 CH 4 measurements should constrain the fossil fraction of past methane budgets, as well as provide a definitive test of methane clathrate involvement in large and rapid methane concentration ([CH 4 ]) increases that accompanied rapid warming events during the last deglaciation. Air dating to the Younger Dryas–Preboreal and Oldest Dryas–Bølling abrupt climatic transitions was obtained by melt extraction from old glacial ice outcropping at an ablation margin in West Greenland. The outcropping ice and occluded air were dated using a combination of δ 15 N of N 2 , δ 18 O of O 2 , δ 18 O ice and [CH 4 ] measurements. The [CH 4 ] blank of the melt extractions was ppb. Measurements of δ 18 O and δ 15 N indicated no significant gas isotopic fractionation from handling. Measured Ar/N 2 , CFC-11 and CFC-12 in the s les indicated no significant contamination from ambient air. Ar/N 2 , Kr/Ar and Xe/Ar ratios in the s les were used to quantify effects of gas dissolution during the melt extractions and correct the s le [CH 4 ]. Corrected [CH 4 ] is elevated over expected values by up to 132 ppb for most s les, suggesting some in situ CH 4 production in ice at this site.
Publisher: Proceedings of the National Academy of Sciences
Date: 14-03-2016
Abstract: Antarctic ice cores provide a precise, well-dated history of increasing atmospheric CO 2 during the last glacial to interglacial transition. However, the mechanisms that drive the increase remain unclear. Here we reconstruct a key indicator of the sources of atmospheric CO 2 by measuring the stable isotopic composition of CO 2 in s les spanning the period from 22,000 to 11,000 years ago from Taylor Glacier, Antarctica. Improvements in precision and resolution allow us to fingerprint CO 2 sources on the centennial scale. The data reveal two intervals of rapid CO 2 rise that are plausibly driven by sources from land carbon (at 16.3 and 12.9 ka) and two others that appear fundamentally different and likely reflect a combination of sources (at 14.6 and 11.5 ka).
Publisher: American Association for the Advancement of Science (AAAS)
Date: 24-04-2009
Abstract: Radiocarbon measurements show that wetlands were responsible for the rapid increase of atmospheric methane concentration during the last deglaciation.
Publisher: Springer Science and Business Media LLC
Date: 12-2014
DOI: 10.1038/NATURE13971
Abstract: Nitrous oxide (N2O) is an important greenhouse gas and ozone-depleting substance that has anthropogenic as well as natural marine and terrestrial sources. The tropospheric N2O concentrations have varied substantially in the past in concert with changing climate on glacial-interglacial and millennial timescales. It is not well understood, however, how N2O emissions from marine and terrestrial sources change in response to varying environmental conditions. The distinct isotopic compositions of marine and terrestrial N2O sources can help disentangle the relative changes in marine and terrestrial N2O emissions during past climate variations. Here we present N2O concentration and isotopic data for the last deglaciation, from 16,000 to 10,000 years before present, retrieved from air bubbles trapped in polar ice at Taylor Glacier, Antarctica. With the help of our data and a box model of the N2O cycle, we find a 30 per cent increase in total N2O emissions from the late glacial to the interglacial, with terrestrial and marine emissions contributing equally to the overall increase and generally evolving in parallel over the last deglaciation, even though there is no a priori connection between the drivers of the two sources. However, we find that terrestrial emissions dominated on centennial timescales, consistent with a state-of-the-art dynamic global vegetation and land surface process model that suggests that during the last deglaciation emission changes were strongly influenced by temperature and precipitation patterns over land surfaces. The results improve our understanding of the drivers of natural N2O emissions and are consistent with the idea that natural N2O emissions will probably increase in response to anthropogenic warming.
Publisher: Copernicus GmbH
Date: 20-07-2017
Abstract: Abstract. Old ice for paleo-environmental studies, traditionally accessed through deep core drilling on domes and ridges on the large ice sheets, can also be retrieved at the surface from ice sheet margins and blue ice areas. The practically unlimited amount of ice available at these sites satisfies a need in the community for studies of trace components requiring large s le volumes. For margin sites to be useful as ancient ice archives, the ice stratigraphy needs to be understood and age models need to be established. We present measurements of trapped gases in ice from Taylor Glacier, Antarctica, to date the ice and assess the completeness of the stratigraphic section. Using δ18O of O2 and methane concentrations, we unambiguously identify ice from the last glacial cycle, covering every climate interval from the early Holocene to the penultimate interglacial. A high-resolution transect reveals the last deglaciation and the Last Glacial Maximum (LGM) in detail. We observe large-scale deformation in the form of folding, but in idual stratigraphic layers do not appear to have undergone irregular thinning. Rather, it appears that the entire LGM–deglaciation sequence has been transported from the interior of the ice sheet to the surface of Taylor Glacier relatively undisturbed. We present an age model that builds the foundation for gas studies on Taylor Glacier. A comparison with the Taylor Dome ice core confirms that the section we studied on Taylor Glacier is better suited for paleo-climate reconstructions of the LGM due to higher accumulation rates.
Location: New Zealand
Location: New Zealand
Location: France
No related grants have been discovered for Hinrich Schaefer.