Enhanced tropical methane production in response to iceberg discharge in the North Atlantic

The causal mechanisms responsible for the abrupt climate changes of the Last Glacial Period remain unclear. One major difficulty is dating ice-rafted debris deposits associated with Heinrich events: Extensive iceberg influxes into the North Atlantic Ocean linked to global impacts on climate and biog...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 2015-05, Vol.348 (6238), p.1016-1019
Main Authors: Rhodes, Rachael H., Brook, Edward J., Chiang, John C. H., Blunier, Thomas, Maselli, Olivia J., McConnell, Joseph R., Romanini, Daniele, Severinghaus, Jeffrey P.
Format: Article
Language:English
Subjects:
Atmospherics
Biogeochemistry
Climate
Climate change
Glacial periods
Heinrich events
Icebergs
Methane
Optics
Paleoclimate science
Physics
Rainfall
Wetlands
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Summary:The causal mechanisms responsible for the abrupt climate changes of the Last Glacial Period remain unclear. One major difficulty is dating ice-rafted debris deposits associated with Heinrich events: Extensive iceberg influxes into the North Atlantic Ocean linked to global impacts on climate and biogeochemistry. In a new ice core record of atmospheric methane with ultrahigh temporal resolution, we find abrupt methane increases within Heinrich stadials 1, 2,4, and 5 that, uniquely, have no counterparts in Greenland temperature proxies. Using a heuristic model of tropical rainfall distribution, we propose that Hudson Strait Heinrich events caused rainfall intensification over Southern Hemisphere land areas, thereby producing excess methane in tropical wetlands. Our findings suggest that the climatic impacts of Heinrich events persisted for 740 to 1520 years.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.1262005