Natural drivers of multidecadal Arctic sea ice variability over the last millennium

Halloran, Paul R.; Hall, Ian R; Menary, Matthew; Reynolds, David J.; Scourse, James; Screen, James A.; Bozzo, Alessio; Dunstone, Nick; Phipps, Steven J.; Schurer, Andrew; Sueyoshi, Tetsuo; Zhou, Tianjun; Garry, Freya

doi:10.1038/s41598-020-57472-2

Cited by 14 publications

(9 citation statements)

References 45 publications

(46 reference statements)

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“…The increased AMOC then in turn corresponds to the positive anomaly in the subtropics to midlatitudes of the BTS. Halloran et al (2020) concluded by analyzing oxygen isotope variability recorded from Iceland and the PMIP3 last millennium ensemble that the same feedback cycle took place in the pre-industrial millennium. In addition, they demonstrate that a third of the multi-decadal Arctic seaice variability can be explained by natural external forcing.…”

Section: Ocean-sea-ice Responsementioning

confidence: 99%

Was there a volcanic-induced long-lasting cooling over the Northern Hemisphere in the mid-6th–7th century?

et al. 2022

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Abstract. The climate of the Northern Hemisphere (NH) in the mid-6th century was one of the coldest during the last 2 millennia based on multiple paleo-proxies. While the onset of this cold period can be clearly connected to the volcanic eruptions in 536 and 540 Common Era (CE), the duration, extent, and magnitude of the cold period are uncertain. Proxy data are sparse for the first millennium, which compounds the uncertainties of the reconstructions. To better understand the mechanisms of the prolonged cooling, we analyze new transient simulations over the Common Era and enhance the representation of mid-6th to 7th century climate by additional ensemble simulations covering 520–680 CE. We use the Max Planck Institute Earth System Model to apply the external forcing as recommended in the Paleoclimate Modelling Intercomparison Project phase 4. After the four large eruptions in 536, 540, 574, and 626 CE, a significant mean surface climate response in the NH lasting up to 20 years is simulated. The 2 m air temperature shows a cooling over the Arctic in winter, corresponding to the increase in Arctic sea ice, mainly in the Labrador Sea and to the east of Greenland. The increase in sea-ice extent relates to a decrease in the northward ocean heat transport into the Arctic within the first 2 years after the eruptions and to an increase in the Atlantic meridional overturning circulation, which peaks 10 years after the eruptions. A decrease in the global ocean heat content is simulated after the eruptions that does not recover during the simulation period. These ocean–sea-ice interactions sustain the surface cooling, as the cooling lasts longer than is expected solely from the direct effects of the volcanic forcing, and are thus responsible for the multi-decadal surface cooling. In boreal summer, the main cooling occurs over the continents at midlatitudes. A dipole pattern develops with high sea level pressure and a decrease in both precipitation and evaporation poleward of 40∘ N. In addition, more pronounced cooling over land compared to ocean leads to an enhanced land–sea contrast. While our model ensemble simulations show a similar ∼20-year summer cooling over NH land after the eruptions as tree ring reconstructions, a volcanic-induced century-long cooling, as reconstructed from tree ring data, does not occur in our simulations.

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Section: Ocean-sea-ice Responsementioning

confidence: 99%

Was there a volcanic-induced long-lasting cooling over the Northern Hemisphere in the mid-6th–7th century?

et al. 2022

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“…Black et al 2014), has the potential to provide quality data for climate models to understand long-term (potentially spanning millennia) variability in the Earth and ocean system (e.g. Halloran et al 2020). Multidisciplinary analyses are key in tackling ecosystem functioning and drawing expertise from several science disciplines.…”

Section: Scope For the Futurementioning

confidence: 99%

Sclerochronology in the Southern Ocean

González

2021

Polar Biol

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This manuscript aims to provide a comprehensive review of the work done by Antarctic sclerochronology research across different taxa (arthropods, bivalves, brachiopods, bryozoans, cephalopods, hard and soft corals, gastropods, echinoderms and teleost fish), provide an analysis of current challenges in the discipline and start a discussion of what sclerochronology can offer for Antarctic research in future. The Southern Ocean ecosystem remains largely unstudied in part for its remoteness, extreme climate and strong seasonality. This lack of knowledge, some of it even on basic biological information, it is especially worrying due to ongoing climate-driven changes that the Southern Ocean ecosystem is experiencing. Lack of long-term in situ instrumental series has also being a detriment to understand long-term feedbacks between the physical environment and the ecosystem. Sclerochronology, the study of periodic accretional patterns in the hard body structures of living organisms, has contributed to a wide range of Antarctic research disciplines (e.g. paleoclimate reconstructions, population structure analysis, environmental proxies). This review highlights a disparity in research focus by taxa with some groups (e.g. bivalves, teleost fish) attracting most of the research attention, whereas other groups (e.g. gastropod) have attracted much little research attention or in some cases it is almost non-existent (e.g. echinoderms). Some of the long-lived species considered in this review have the potential to provide the much-needed high-resolution eco-environmental proxy data and play an important role in blue carbon storage in the Sothern Ocean. Another issue identified was the lack of cross-validation between analytical techniques. Graphic abstract

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“…It has been argued that around Iceland variations in δ 18 O c of planktic foraminiferal species over the last 10 ka are principally controlled by temperature variations while salinity changes prove less important [64]. Conversely, the δ 18 O-shell record of the marine bivalve mollusc Arctica islandica collected equally from the NIS was considered to represent seawater density changes, which is the combined product of seawater temperature and salinity [13,25].…”

Section: Comparison Of Foraminifera Proxy Data and Instrumental Recordsmentioning

confidence: 99%

“…An ongoing question in the community is, however, if the detected climate variability is an internal mode of the climate system or is externally forced [6][7][8][9]. Evidence for multidecadal variability in records over the last 1 ka indicate that this type of variability may be internal (for example, ocean heat storage and transport), or alternatively linked to the interactions between fluctuations in total solar irradiance and volcanic aerosols [10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

A multi-decadal record of oceanographic changes of the past ~165 years (1850-2015 AD) from Northwest of Iceland

et al. 2020

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Extending oceanographic data beyond the instrumental period is highly needed to better characterize and understand multi-decadal to centennial natural ocean variability. Here, a stable isotope record at unprecedented temporal resolution (1 to 2 years) from a new marine core retrieved off western North Iceland is presented. We aim to better constrain the variability of subsurface, Atlantic-derived Subpolar Mode Water (SPMW), using near surface-dwelling planktic foraminifera and Arctic Intermediate Water (AIW) mass changes using benthic foraminifera over the last~165 years. The reconstruction overlaps in time with instrumental observations and a direct comparison reveals that the δ 18 O record of Neogloboquadrina pachyderma is reliably representing temperature fluctuations in the SPMWs. Trends in the N. pachyderma δ 13 C record match the measured phosphate concentration in the upper 200 m on the North Icelandic Shelf well. Near surface-dwelling foraminifera trace anthropogenic CO 2 in the Iceland Sea by~1950 ± 8, however, a reduced amplitude shift in the Marine Suess effect is identified. We argue that this is caused by a contemporary ongoing increase in marine primary productivity in the upper ocean due to enhanced Greenland's freshwater discharge that has contributed to a nutrient-driven fertilization since the 1940s/50s (Perner et al., 2019). Multi-decadal variability is detected. We find that the 16-year periodicity evident in SPMW and AIWs based on the δ 18 O of N. pachyderma and M. barleeanum is a signal of SST anomalies propagated into the Nordic Seas via the Atlantic inflow branches around Iceland. Spectral analyses of the planktic foraminiferal δ 13 C signal indicate intermittent 30-year cycles that are likely reflecting the ocean response to atmospheric variability, presumably the East Atlantic Pattern. A long-term trend in benthic δ 18 O suggests that Atlantic-derived waters are expanding their core within the water column from the subsurface into deeper intermediate depths towards the present day. This is a result of increased transport by the North Icelandic Irminger Current to the North Iceland Shelf over the historical era.

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Natural drivers of multidecadal Arctic sea ice variability over the last millennium

Cited by 14 publications

References 45 publications

Was there a volcanic-induced long-lasting cooling over the Northern Hemisphere in the mid-6th–7th century?

Was there a volcanic-induced long-lasting cooling over the Northern Hemisphere in the mid-6th–7th century?

Sclerochronology in the Southern Ocean

A multi-decadal record of oceanographic changes of the past ~165 years (1850-2015 AD) from Northwest of Iceland

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