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 seasurface 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.

The last two millennia: climate, ocean circulation and palaeoproductivity inferred from planktic foraminifera, south-western Svalbard margin

“…Climatic periods and their timing defined historically in north-western Europe by Lamb (1977) correlate with major changes in proxy records in the North Atlantic and Nordic seas region. They indicate temperature and productivity changes on multidecadal to centennial timescales with prominent cold and warm anomalies (e.g., Jiang et al 2002;Spielhagen et al 2011;Andresen et al 2013;Matul et al 2018). Increased inflow of warm subsurface Atlantic Water from the Norwegian Sea into the Arctic Ocean via the eastern Fram Strait is considered to be responsible for the warm intervals associated with the Roman Warm Period, the Medieval Climate Anomaly and the Recent Warming (Spielhagen et al 2011;Werner et al 2011;Zamelczyk et al 2013;Werner et al 2016).…”

“…Increased inflow of warm subsurface Atlantic Water from the Norwegian Sea into the Arctic Ocean via the eastern Fram Strait is considered to be responsible for the warm intervals associated with the Roman Warm Period, the Medieval Climate Anomaly and the Recent Warming (Spielhagen et al 2011;Werner et al 2011;Zamelczyk et al 2013;Werner et al 2016). However, depending on the environmental settings, proximity of the sea-ice edge, availability of nutrients, microfossil types and other proxies, the productivity signals may vary considerably (Matul et al 2018;Moffa-Sánchez et al 2019). We compare our temperature estimates and flux of the subsurface dwelling N. pachyderma and near-surface to surface living T. quinqueloba and G. uvula as indicators of subsurface and near-surface to surface water productivity, respectively, to other records based on planktic foraminifera and other microfossils indicative of biological production in Fram Strait and northern North Atlantic (Figs.…”

“…Moreover, high productivity at the near-surface to surface in this area is also indicated by a high concentration of phytoplankton biomarkers at about 340 AD and high flux of diatoms at ca. 46-455 AD (Müller et al 2012;Matul et al 2018). These conditions are linked to a northward retreat of the sea-ice edge due to strengthened Atlantic Water inflow and/or changes in the atmospheric circulation pattern (Werner et al 2011;Müller et al 2012;Matul et al 2018).…”

They Came From the Pacific: How Changing Arctic Currents Could Contribute to an Ecological Regime Shift in the Atlantic Ocean

“…This species was observed by a Continuous Plankton Recorder (CPR) survey in the Atlantic Ocean in 1999, seemingly its first occurrence in the Atlantic for millennia, and Reid et al () proposed accelerated connectivity due to reduced sea ice cover as an explanation. Subsequent analysis of sediment cores has suggested that, although not found in any CPR surveys prior to 1999, the species may in fact have been present in the Fram Strait as early as 1989 (Matul et al, ).…”

How long will an Arctic mountain glacier survive? A case study of Austre Lovénbreen, Svalbard

“…Small glaciers also have impacts on river discharge and energy exchange within basins (Verbunt et al 2003). Svalbard (10°-35°E, 74°-81°N) is located in close proximity to the warm West Spitsbergen Current (Matul et al 2018), and the mass balance of glaciers in the archipelago is very sensitive to fluctuations in this current and the corresponding climate changes (Xu et al 2007). At present, Svalbard is an international hotspot for glacier research.…”