Abstract
During the Bølling–Allerød warm period of the last deglaciation, about 14 kyr ago, there was a strong and pervasive spike in primary productivity in the North Pacific Ocean1. It has been suggested that this productivity event was caused by an influx of the micronutrient iron from surrounding continental shelves as they were flooded by sea-level rise2. Here we test this hypothesis by comparing numerous proxies of productivity with iron flux and provenance measured from a core from the subarctic Pacific Ocean. We find no evidence for an abrupt deglacial pulse of iron from any source at the time of peak productivity. Instead, we argue that the deglacial productivity peak was caused by two stepwise events. First, deep convection during early deglaciation increased nutrient supply to the surface but also increased the depth of the mixed layer, which pushed surface production deeper in the water column and induced light limitation. A subsequent input of meltwater from northern American ice sheets then stratified the water column, which relieved light limitation while leaving the surface waters enriched in nutrients. We conclude that iron plays, at most, a secondary role in controlling productivity during the glacial and deglacial periods in the subarctic Pacific Ocean.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 12 print issues and online access
$259.00 per year
only $21.58 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Kohfeld, K. E. & Chase, Z. Controls on deglacial changes in biogenic fluxes in the North Pacific Ocean. Quat. Sci. Rev. 30, 3350–3363 (2011).
Davies, M. H. et al. The deglacial transition on the southeastern Alaska Margin: Meltwater input, sea level rise, marine productivity, and sedimentary anoxia. Paleoceanography 26, PA2223 (2011).
Boyd, P. W. et al. Mesoscale iron enrichment experiments 1993–2005: Synthesis and future directions. Science 315, 612–617 (2007).
Murray, R. W., Leinen, M. & Knowlton, C. W. Links between iron input and opal deposition in the Pleistocene equatorial Pacific Ocean. Nature Geosci. 5, 270–274 (2012).
Kienast, S. S., Hendy, I. L., Crusius, J., Pedersen, T. F. & Calvert, S. E. Export production in the subarctic North Pacific over the last 800 kyrs: No evidence for iron fertilization? J. Oceanogr. 60, 189–203 (2004).
Mahowald, N. M. et al. Atmospheric iron deposition: Global distribution, variability, and human perturbations. Annu. Rev. Mar. Sci. 1, 245–278 (2009).
Lam, P. J. & Bishop, J. K. B. The continental margin is a key source of iron to the HNLC North Pacific Ocean. Geophys. Res. Lett. 35, L07608 (2008).
Nishioka, J. et al. Iron supply to the western subarctic Pacific: Importance of iron export from the Sea of Okhotsk. J. Geophys. Res. 112, C10012 (2007).
Hamme, R. C. et al. Volcanic ash fuels anomalous plankton bloom in subarctic northeast Pacific. Geophys. Res. Lett. 37, L19604 (2010).
Mahowald, N., Albani, S., Engelstaedter, S., Winckler, G. & Goman, M. Model insight into glacial—interglacial paleodust records. Quat. Sci. Rev. 30, 832–854 (2011).
Otosaka, S., Honda, M. C. & Noriki, S. La/Yb and Th/Sc in settling particles: Vertical and horizontal transport of lithogenic material in the western North Pacific. Geochem. J. 38, 515–525 (2004).
Keigwin, L. D. Glacial-age hydrography of the far northwest Pacific Ocean. Paleoceanography 13, 323–339 (1998).
Yokoo, Y., Nakano, T., Nishikawa, M. & Quan, H. Mineralogical variation of Sr-Nd isotopic and elemental compositions in loess and desert sand from the central Loess Plateau in China as a provenance tracer of wet and dry deposition in the northwestern Pacific. Chem. Geol. 204, 45–62 (2004).
VanLaningham, S., Pisias, N. G., Duncan, R. A. & Clift, P. D. Glacial–interglacial sediment transport to the Meiji Drift, northwest Pacific Ocean: Evidence for timing of Beringian outwashing. Earth Planet. Sci. Lett. 277, 64–72 (2009).
Millot, R., Gaillardet, J. é, Dupré, B. & Allègre, C. J. Northern latitude chemical weathering rates: Clues from the Mackenzie River Basin, Canada. Geochim. Et Cosmochim. Acta 67, 1305–1329 (2003).
Kohfeld, K. E. & Harrison, S. P. DIRTMAP: The geological record of dust. Earth-Sci. Rev. 54, 81–114 (2001).
Keigwin, L. D., Donnelly, J. P., Cook, M. S., Driscoll, N. W. & Brigham-Grette, J. Rapid sea-level rise and Holocene climate in the Chukchi Sea. Geology 34, 861–864 (2006).
Jaccard, S. L. et al. Glacial/interglacial changes in subarctic north pacific stratification. Science 308, 1003–1006 (2005).
Galbraith, E. D. et al. Carbon dioxide release from the North Pacific abyss during the last deglaciation. Nature 449, 890–893 (2007).
Anderson, R. et al. Wind-driven upwelling in the Southern Ocean and the deglacial rise in atmospheric CO2. Science 323, 1443–1448 (2009).
Stanford, J. et al. Sea-level probability for the last deglaciation: A statistical analysis of far-field records. Glob. Planet. Change 79, 193–203 (2011).
Brunelle, B. G. et al. Glacial/interglacial changes in nutrient supply and stratification in the western subarctic North Pacific since the penultimate glacial maximum. Quat. Sci. Rev. 29, 2579–2590 (2010).
Hu, A. et al. The Pacific-Atlantic seesaw and the Bering Strait. Geophys. Res. Lett. 39, L03702 (2012).
Jaccard, S. L. & Galbraith, E. D. Direct ventilation of the North Pacific did not reach the deep ocean during the last deglaciation. Geophys. Res. Lett. 40, 199–203 (2013).
Obata, A., Ishizaka, J. & Endoh, M. Global verification of critical depth theory for phytoplankton bloom with climatological in situ temperature and satellite ocean color data. J. Geophys. Res. 101, 20657–20667 (1996).
Keigwin, L. D., Jones, G. A. & Froelich, P. N. A 15,000 year paleoenvironmental record from Meiji Seamount, far northwestern Pacific. Earth Planet. Sci. Lett. 111, 425–440 (1992).
Haug, G. H. & Sigman, D. M. Palaeoceanography: Polar twins. Nature Geosci. 2, 91–92 (2009).
Burke, A. & Robinson, L. F. The Southern Ocean’s role in carbon exchange during the last deglaciation. Science 335, 557–561 (2012).
Roche, D. M., Crosta, X. & Renssen, H. Evaluating Southern Ocean sea-ice for the Last Glacial Maximum and pre-industrial climates: PMIP-2 models and data evidence. Quat. Sci. Rev. 56, 99–106 (2012).
Acknowledgements
This work was supported by the Lawrence J. Pratt and Melinda M. Hall Endowed Award for Interdisciplinary Research to L.F.R., P.J.L. and J.B.; the Marie-Curie Reintegration programme, European Research Council no. 278705 to L.F.R.; National Science Foundation (NSF) to P.J.L.; the Centre for Climate Dynamics at the Bjerknes Centre to C.L.; the Comer Science and Education Fund and the US NSF to J.F.M.; and NSF OCE-1031224 to L.D.K. Thanks to J. Goudreau for U-series help, E. Crapster-Pregont, J. Swartz, D. Ohnemus and M. Auro for sediment leaches, M. Carman for assistance with foraminiferal abundance counts, C. M. Bitz for providing ocean boundary conditions for the 14 kyr simulation and C. Lamborg, J. Rae and A. Mahadevan for stimulating discussions.This is publication no. A423 from the Bjerknes Centre for Climate Research.
Author information
Authors and Affiliations
Contributions
P.J.L., L.F.R. and J.B. conceived the project. L.F.R. conducted U-series measurements; J.B. conducted Nd and Sr isotope measurements; C.L. provided G.C.M. output; J.F.M. measured sediment composition; M.S.C. provided the age model and foraminiferal abundances; L.D.K. provided volcanic ash shard counts; P.J.L. measured soluble Fe and wrote the paper; all helped with interpretations and commented on the manuscript.
Corresponding author
Ethics declarations
Competing interests
The authors declare no competing financial interests.
Supplementary information
Supplementary Information
Supplementary Information (PDF 751 kb)
Supplementary Information
Supplementary Information (CSV 11 kb)
Supplementary Information
Supplementary Information (CSV 1 kb)
Rights and permissions
About this article
Cite this article
Lam, P., Robinson, L., Blusztajn, J. et al. Transient stratification as the cause of the North Pacific productivity spike during deglaciation. Nature Geosci 6, 622–626 (2013). https://doi.org/10.1038/ngeo1873
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1038/ngeo1873
This article is cited by
-
Asian dust-deposition flux to the subarctic Pacific estimated using single quartz particles
Scientific Reports (2023)
-
Volcanic trigger of ocean deoxygenation during Cordilleran ice sheet retreat
Nature (2022)
-
Revisit of thorium-based dust fluxes and their implications for the iron fertilization hypothesis
Journal of Oceanography (2022)
-
Deglacial upwelling, productivity and CO2 outgassing in the North Pacific Ocean
Nature Geoscience (2018)
-
Aerosol-Climate Interactions During the Last Glacial Maximum
Current Climate Change Reports (2018)