Тип публикации: статья из журнала
Год издания: 2009
Идентификатор DOI: 10.1029/2008GB003330
Ключевые слова: Atmospheric methanes, Biogeochemical cycle, Climate indicators, Cross-spectral analysis, Data sets, Greenland, Greenland Ice Sheet, High resolution, High-precision, Ice core, Last glacial period, Local temperature, Measurement precision, Methane concentrations, Oxygen isotopes, Relative timing, Time interval, Time resolution, Time-scales, Analytical geochemistry, Atmospheric chemistry, Biogeochemistry, Global warming, Greenhouse gases, Ice, Isotopes, Methanation, Oxygen, Spectrum analysis, Spectrum analyzers, Methane, climate conditions, greenhouse gas, Last Glacial, oxygen isotope, Arctic
Аннотация: The global biogeochemical cycle of methane has received wide attention because of methane's role as a greenhouse gas. Measurements of methane in air trapped in Greenland ice cores provide a high-resolution record of methane levels in the atmosphere over the past similar to 100 ka, providing clues about what controls the methane cycПоказать полностьюle on geologic timescales. Remarkable similarity between local temperature recorded in Greenland ice cores and changes in global methane concentrations has been noted in previous studies, with the inference that the local temperature variations have global significance, but the resolution of sampling and measurement precision limited fine-scale comparison of these variables. In this work a higher-precision (similar to 2 ppb) methane data set was obtained from the Greenland Ice Sheet Project 2 (GISP2) ice core for the time interval between 86 and 68 ka, encompassing three large abrupt warming events early in the last glacial period: Dansgaard-Oeschger (D-O) events 19, 20, and 21. The new data set consists of duplicate measurements at 158 depths, with average time resolution of 120 years. Such detailed measurements over D-O 21, the longest in Greenland records, have not yet been reported for other ice cores. The new data set documents short-term variability (similar to 20 ppb typical amplitude), which is remarkably persistent, and in many cases similar features are observed in the most detailed published delta O-18(ice) record. High-precision GISP2 delta N-15 data show that changes in Greenland temperature are synchronous with the methane variations at the onset of D-O events 19, 20, and 21, supporting previous results from the Greenland Ice Core Project ice core for D-O 19 and 20. Cross-spectral analysis quantifies the extremely close similarity between the new methane record and the delta O-18(ice) record. Because methane sources are widely distributed over the globe, this work further validates delta O-18(ice) at Greenland summit as a geographically broad climate indicator on millennial to multicentennial timescales.
Журнал: GLOBAL BIOGEOCHEMICAL CYCLES
Выпуск журнала: Vol. 23
ISSN журнала: 08866236
Место издания: WASHINGTON
Издатель: AMER GEOPHYSICAL UNION