Publications by authors named "James A Menking"
Understanding the causes of past atmospheric methane (CH) variability is important for characterizing the relationship between CH, global climate and terrestrial biogeochemical cycling. Ice core records of atmospheric CH contain rapid variations linked to abrupt climate changes of the last glacial period known as Dansgaard-Oeschger (DO) events and Heinrich events (HE). The drivers of these CH variations remain unknown but can be constrained with ice core measurements of the stable isotopic composition of atmospheric CH, which is sensitive to the strength of different isotopically distinguishable emission categories (microbial, pyrogenic and geologic).
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- The study examines abrupt climate changes during the Pleistocene Ice Ages, known as Dansgaard-Oeschger (DO) oscillations, using Greenland ice cores to analyze temperature shifts and their potential long-term impacts.
- It introduces new ice-core records from southern and eastern Greenland to enhance understanding of DO event magnitudes and creates a multiproxy assessment of their effects across Greenland.
- The findings suggest that variations in wintertime sea ice in the North Atlantic subpolar gyre are crucial for explaining DO variability, and that changes in vapor source distribution, rather than site temperature, mainly influence Greenland's isotope signals during these climate transitions.
Here we use high-precision carbon isotope data (δC-CO) to show atmospheric CO during Marine Isotope Stage 4 (MIS 4, ~70.5-59 ka) was controlled by a succession of millennial-scale processes. Enriched δC-CO during peak glaciation suggests increased ocean carbon storage.
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