Climate changes modulated the history of Arctic iodine during the Last Glacial Cycle

Juan Pablo Corella,Carlos A Cuevas,Carlo Barbante,Bo Vinther,Alfonso Saiz-Lopez,Juliane Müller,Paul Vallelonga,Ross Edwards,Andrea Spolaor,Federico Scoto,Helle A Kjær,Giulio Cozzi,Niccolo Maffezzoli

doi:10.1038/s41467-021-27642-5

Abstract

Iodine has a significant impact on promoting the formation of new ultrafine aerosol particles and accelerating tropospheric ozone loss, thereby affecting radiative forcing and climate. Therefore, understanding the long-term natural evolution of iodine, and its coupling with climate variability, is key to adequately assess its effect on climate on centennial to millennial timescales. Here, using two Greenland ice cores (NEEM and RECAP), we report the Arctic iodine variability during the last 127,000 years. We find the highest and lowest iodine levels recorded during interglacial and glacial periods, respectively, modulated by ocean bioproductivity and sea ice dynamics. Our sub-decadal resolution measurements reveal that high frequency iodine emission variability occurred in pace with Dansgaard/Oeschger events, highlighting the rapid Arctic ocean-ice-atmosphere iodine exchange response to abrupt climate changes. Finally, we discuss if iodine levels during past warmer-than-present climate phases can serve as analogues of future scenarios under an expected ice-free Arctic Ocean. We argue that the combination of natural biogenic ocean iodine release (boosted by ongoing Arctic warming and sea ice retreat) and anthropogenic ozone-induced iodine emissions may lead to a near future scenario with the highest iodine levels of the last 127,000 years.

Highlights

Iodine has a significant impact on promoting the formation of new ultrafine aerosol particles and accelerating tropospheric ozone loss, thereby affecting radiative forcing and climate
Atmospheric iodine in Greenland is controlled by a complex interplay involving iodine emissions from the oceans, as well as particle-bound iodine compounds related to dust and/or sea spray aerosol variability[23]
Maximum iodine levels were found during the Eemian in the NEEM ice core, with a total mean iodine depositional flux (Iflux) of 9.6 μg m−2 yr−1 coinciding with the highest Arctic Ocean primary productivity inferred from the phytoplankton biomarker brassicasterol[35] (Fig. 2)

Summary

Introduction

Iodine has a significant impact on promoting the formation of new ultrafine aerosol particles and accelerating tropospheric ozone loss, thereby affecting radiative forcing and climate. In the Arctic, a coastal ice core from Greenland revealed that ocean primary productivity controlled atmospheric iodine variability during the Holocene (i.e., last 11,700 years)[19].

Results

Conclusion