title: Paleoclimate. Enhanced tropical methane production in response to iceberg discharge in the North Atlantic.
abstract: 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.
authors.affiliation: College of Earth, Ocean, and Atmospheric Sciences, 104 CEOAS Administration, Oregon State University, Corvallis, OR 97331, USA. rhodesra@geo.oregonstate.edu.
authors.forename: Rachael H
authors.initials: RH
authors.lastname: Rhodes
authors.affiliation: College of Earth, Ocean, and Atmospheric Sciences, 104 CEOAS Administration, Oregon State University, Corvallis, OR 97331, USA.
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Brook
authors.affiliation: Department of Geography and Berkeley Atmospheric Sciences Center, University of California, Berkeley, CA, USA.
authors.forename: John C H
authors.initials: JC
authors.lastname: Chiang
authors.affiliation: Center for Ice and Climate, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Thomas
authors.initials: T
authors.lastname: Blunier
authors.affiliation: Division of Hydrologic Sciences, Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512, USA.
authors.forename: Olivia J
authors.initials: OJ
authors.lastname: Maselli
authors.affiliation: Division of Hydrologic Sciences, Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512, USA.
authors.forename: Joseph R
authors.initials: JR
authors.lastname: McConnell
authors.affiliation: Joseph Fourier University-Grenoble 1/CNRS, LIPhy UMR 5588, Grenoble, F-38041, France.
authors.forename: Daniele
authors.initials: D
authors.lastname: Romanini
authors.affiliation: Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0244, USA.
authors.forename: Jeffrey P
authors.initials: JP
authors.lastname: Severinghaus