Paleoclimate; Polar Ocean; Atmospheric CO2; Polar Oceans; atmospheric carbon dioxide; Late Neogene climate
Straub M, Sigman D.M., Ren H., Martinez Garcia A., Meckler A.N., Hain M.P., Haug G. (2013), Circulation control of North Atlantic nitrogen fixation changes, in Nature
, 501(7466), 1-5.
Meckler A.N., Sigmann D.N., Gibson K., Francois R, Martinez Garcia A., Jaccard S.L., Röhl U., Peterson L.C., Tiedemann R, Haug G.H. (2013), Deglacial pulses of deep ocean silicate into the subtropical North Atlantic over the past 550,000 years, in Nature
, 495, 495-499.
Straub M., Tremblay M.M., Sigman D.M., Studer A., Ren H., Toggweiler J.R, Haug G.H. (2013), Nutrient conditions in the subpolar North Atlantic during the last glacial period reconstructed from foraminifera-bound nitrogen isotopes, in Paleoceanography
Studer A.S., Ellis K.K., Oleynik S., Sigman D.M., Hodell D.A., Haug G.H (2013), Size-specific opal-bound isotope measurements in North Pacific sediments, in Geochimica and Cosmochimica Acta
, 120, 179-194.
Jaccard S.L, Hayes C.T., Martinez Garcia A, Hodell D.A., Anderson R.F., Sigman D.M., Haug G.H. (2013), The roles of the Antaractic and Subantarctic Zones in ocean productivity and atmospheric CO2 over the million years, in Science
, 339, 1419-1423.
Studer A.S., Martinez Garcia A., Jaccard S.L., Girault F.E., Sigman D.M., Haug D.M. (2012), Enhanced stratification and seasonality in the Subarctic Pacific upon Northern Hemisphere Glaciation-New evidence from diatom-bound nitrogen isotopes, alkenones and archaeal tetraethers, in Earth and Planetary Science Letters
, 351, 84-94.
Martinez Garcia A., Rosell-Mele A., Jaccard S.L., Geibert W., Sigman D.M., Haug G.H. (2011), Southern Ocean dust-climate coupling over the last 4 million years, in Nature
, 476, 312-315.
Martinez-Garcia A, Rosell-Mele A, Jaccard SL, Geibert W, Sigman DM, Haug GH (2011), Southern Ocean dust-climate coupling over the past four million years, in NATURE
, 476(7360), 312-316.
Martinez Garcia A., Sigman D.M., Ren H., Anderson R.F., Straub M., Hodell D.A., Jaccard S.L., Eglinton T.I., Haug G.H., Iron fertilization of the Subantarctic Ocean during the last ice age, in Science
Polar Twins: Southern Ocean and subarctic North Pacific Paleoceanography We propose to investigate the causes and effects of changes in the circulation and carbon fluxes of these nutrient-rich polar ocean regions over glacial/interglacial cycles and during warmer intervals of the Cenozoic such as the Pliocene warm interval, the most recent geological analog of the predicted anthropogenic climate e.g. (Zachos et al., 2001). In particular, we seek to understand the role of the polar oceans in past atmospheric carbon dioxide (CO2) changes, a question of central importance to predicting the future of CO2 and climate in the context of human perturbation. The climate sensitivities of polar ocean circulation and biological productivity are also critical in their own right, as the polar ocean regions affect global heat transport, albedo, continental ice dynamics, and marine biological resources. Our goal is to characterize the climate thresholds and feedbacks that might emerge in a warmer world. One aspect of this work will deal with the central importance of the vertical stability in the polar oceans as a driver of atmospheric CO2 changes over the course of the Neogene via changes in the global efficiency of the so-called ‘biological pump’.The past changes in the polar twins may have much to tell us about their future. Climate models of anthropogenic warming predict a future increase in the stratification of these regions, with consequences for productivity and the fluxes of energy and CO2 (Sarmiento et al., 1998). Yet, the accumulated paleoclimate data from the polar twins appear to argue for the opposite response, with stronger stratification in cold climates, not warm ones. A generation of new data based on novel techniques and new sediment cores (Fig. 1) from IODP Expedition 323 to the Bering Sea (cruise participant: Dr. Gretta Bartoli/ETH), the ‚INOPEX’ cruise with the RV ‚Sonne’ to the subarctic North Pacific (cruise participant: Anja Studer/ETH) and the ANT XXVI/2 cruise with RV ‚Polarstern’ to the Pacific sector of the Southern Ocean (cruise participants: Marietta Straub & Dr. Alfredo Martinez-Garcia/ETH) will yield new data that will help to explain this remarkable disconnect between data regarding the past and model predictions of the future.For ‚The Northern Twin’, the Subarctic North Pacific and Bering Sea, we propose (1) To investigate the connections between the Pacific-Arctic-Atlantic Oceans, with an emphasis on surface ocean nutrient status, productivity and overturning changes during the Plio-Pleistocene. (2) To provide further insight on the central importance of the vertical stability in the high latitude regions as a driver of atmospheric CO2 changes over the course of the late Cenozoic. (3) To create new paleoceanographic and paleoclimatic time series based on a multi-proxy approach using new and innovative reconstruction methods such as diatom- and foraminifera-bound N isotopes, XRF scanning and organic biomarkers (alkenones, n-alkanes, chlorins, glycerol dibiphytanyl glycerol tetraethers (GDGTs)), with a focus on (1) the last 1.4 million years (Myr) including the evolution from the 40 kyr to the 100 kyr world, (2) the 2.7 Myr climate transition, (3) the hypothesized changes in Bering Sea through-flow as a consequence of the closure of the Central American Seaway.For ‚The Southern Twin’, we propose (1) To address the surface ocean nutrient status, productivity and overturning changes in the Southern Ocean north and south of the polar front during the Plio-Pleistocene on orbital to centennial timescales. (2) To further our understanding in the role of the Southern Ocean in glacial/interglacial CO2 variations and during the onset of Northern Hemisphere Glaciation 2.7 Myr ago. (3) To reconstruct the role of the Southern Ocean in global deep-water ventilation at glacial/interglacial to centennial timescales.We will measure downcore records of (1) elemental composition as measured by non-destructive scanning XRF (including important and with previous instruments undectectable elements like Ba, Al and possibly U), (2) bulk sediment- and diatom- and foraminifera-bound N isotopes (in collaboration with my long term collaborator Prof. Daniel M. Sigman at Princeton University), (3) redox-sensitive trace metals (Mn, U, Mo) and (4) biomarker-based proxies.