Iron in the NEEM ice core relative to Asian loess records over the last glacial-interglacial cycle

Cunde Xiao; Zhiheng Du; Mike J Handley; Paul A Mayewski; Junji Cao; Simon Schüpbach; Tong Zhang; Jean-Robert Petit; Chuanjin Li; Yeongcheol Han; Yuefang Li; Jiawen Ren

doi:10.1093/nsr/nwaa144

Iron in the NEEM ice core relative to Asian loess records over the last glacial-interglacial cycle

Natl Sci Rev. 2020 Jun 26;8(7):nwaa144. doi: 10.1093/nsr/nwaa144. eCollection 2021 Jul.

Authors

Affiliations

¹ State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China.
² State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China.
³ Climate Change Institute, School of Earth and Climate Sciences, University of Maine, Orono, ME 04469, USA.
⁴ Key Laboratory of Aerosol Science and Technology, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China.
⁵ Climate and Environmental Physics, Physics Institute, University of Bern, Bern 3012, Switzerland.
⁶ Institute of Tibetan Plateau and Polar Meteorology, Chinese Academy of Meteorological Sciences, Beijing 100081, China.
⁷ Institut des Geosciences de I'Environment (IGE), University Grenoble Alpes, Grenoble F38000, France.
⁸ Korea Polar Research Institute, Incheon 21990, Korea.

Abstract

Mineral dust can indirectly affect the climate by supplying bioavailable iron (Fe) to the ocean. Here, we present the records of dissolved Fe (DFe) and total Fe (TDFe) in North Greenland Eemian Ice Drilling (NEEM) ice core over the past 110 kyr BP. The Fe records are significantly negatively correlated with the carbon-dioxide (CO₂) concentrations during cold periods. The results suggest that the changes in Fe fluxes over the past 110 kyr BP in the NEEM ice core are consistent with those in Chinese loess records because the mineral-dust distribution is controlled by the East Asian deserts. Furthermore, the variations in the dust input on a global scale are most likely driven by changes in solar radiation during the last glacial-interglacial cycle in response to Earth's orbital cycles. In the last glacial-interglacial cycle, the DFe/TDFe ratios were higher during the warm periods (following the post-Industrial Revolution and during the Holocene and last interglacial period) than during the main cold period (i.e. the last glacial maximum (LGM)), indicating that the aeolian input of iron and the iron fertilization effect on the oceans have a non-linear relationship during different periods. Although the burning of biomass aerosols has released large amounts of DFe since the Industrial Revolution, no significant responses are observed in the DFe and TDFe variations during this period, indicating that severe anthropogenic contamination has no significant effect on the DFe (TDFe) release in the NEEM ice core.

Keywords: Chinese loess; Greenland NEEM ice core; carbon dioxide; glacial–interglacial cycle; iron fertilization.