Warm-water events in the eastern Fram Strait during the last 2000 years as revealed by different microfossil groups

ABSTRACT

The environmental system of the northern Nordic Seas is very sensitive to oceanographic and climatic changes at the contact of cold Arctic and warmer North Atlantic waters. These contrasts are reflected in the associations of marine microorganisms and archived in the bottom sediments. A microfossil study (diatoms, coccoliths) of late Holocene sediments in core MSM5/5-712-1 from the eastern Fram Strait provides a better understanding of marine ecosystems and palaeoenvironments during Arctic warming events of the last two millennia. Indicative diatom species and groups of species revealed a high variability of sea-surface conditions. Based on the diatom distribution, three warming periods could be detected, corresponding to the time intervals of 0 to 440 CE (the later part of the Roman Warm Period), 1200 to1420 CE (the final part of the Medieval Climate Anomaly) and 1730 CE to present (including the Recent Warming). The various micropalaeontological proxies used in this study and other publications describe the Roman Warm Period and, especially, the Recent Warming as the most pronounced warm events in the area during the last 2000 years. A comparison of data from the different microfossil groups, indicators of sea-surface and subsurface conditions, reveals variable, complicated and non-simultaneous palaeoenvironmental signals within the warm periods. This can potentially be explained by changes in the surface/subsurface water structure during the events (variations in the cold/warm water advection, stratification, availability of nutrients, seasonal succession of bioproductivity, etc.), which are reflected by changes in the microplankton communities.

KEYWORDS:

• Arctic warming
• late Holocene
• micropalaeontology
• sea surface/subsurface palaeoenvironments

ABBREVIATIONS:

• AW: Atlantic Water
• BC: before the Christian era
• CE: Christian era
• DACP: Dark Ages Cold Period
• kyr: thousands of years
• LIA: Little Ice Age
• MCA: Medieval Climate Anomaly
• RW: Recent Warming
• RWP: Roman Warm Period
• SST: sea-surface temperature

Acknowledgements

We are grateful to the two anonymous reviewers for their valuable and constructive comments and suggestions that helped to improve the manuscript significantly. The investigated sediment core was retrieved during an expedition of RV Maria S. Merian.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported primarily by the Russian Science Foundation and Department of Science and Technology of the Ministry of Science and Technology of India under grant no. 16-47-02009. The funds for the same were extended by the National Centre for Polar and Ocean Research, Goa, Ministry of Earth Sciences; RM would like to thank the director of that institution for extending support to this project. Micropalaeontological work was supported by Shirshov Institute of Oceanology project no. 0149-2018-0016, granted by the Russian Federal Agency of Scientific Organizations. The expedition of RV Maria S. Merian during which the investigated sediment core was retrieved was funded by the Deutsche Forschungsgemeinschaft. This is National Centre for Polar and Ocean Research contribution no. 62/2018.