Spatial variation of hydroclimate in north-eastern North America during the last millennium

Mackay, Helen M. M.; Amesbury, Matthew J.; Langdon, Peter G.; Charman, Dan; Magnan, Gabriel; Bellen, Simon van; Garneau, Michelle; Bainbridge, Rupert; Hughes, Paul

doi:10.1016/j.quascirev.2021.106813

Cited by 7 publications

(4 citation statements)

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“…The peatland sampling approaches used here are outlined in Mackay et al (2021), and testate amoeba analysis was completed using standard protocols (Hendon and Charman, 1997;Booth et al, 2010) across all cores at a multidecadal resolution (approximately 40 years), equating to 2 to 4 cm intervals. Testate amoebae were extracted from 1 cm 3 subsamples following standard procedures (Hendon and Charman, 1997;Booth et al, 2010).…”

Section: Testate Amoebae Peatland Water Table Depth (Ie Summer Effect...mentioning

confidence: 99%

“…Two WTD reconstructions exist from different coring locations on Sidney Bog, Maine (Clifford and Booth, 2013;Mackay et al, 2021); therefore, a composite record was constructed based on interpolated average WTD values (Appendix E). Two WTD reconstructions also exist from different coring locations on Saco Heath (Clifford and Booth, 2013;Mackay et al, 2021); however, a composite record was not created for this site since one record contains a pronounced hiatus below the WRAe horizon, relating to a burning event (Clifford and Booth, 2013). The Saco record presented within this study contains no evidence of a hiatus until later in the record, ca.…”

Section: Testate Amoebae Peatland Water Table Depth (Ie Summer Effect...mentioning

confidence: 99%

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The 852/3 CE Mount Churchill eruption: examining the potential climatic and societal impacts and the timing of the Medieval Climate Anomaly in the North Atlantic region

et al. 2022

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Abstract. The 852/3 CE eruption of Mount Churchill, Alaska, was one of the largest first-millennium volcanic events, with a magnitude of 6.7 (VEI 6) and a tephra volume of 39.4–61.9 km3 (95 % confidence). The spatial extent of the ash fallout from this event is considerable and the cryptotephra (White River Ash east; WRAe) extends as far as Finland and Poland. Proximal ecosystem and societal disturbances have been linked with this eruption; however, wider eruption impacts on climate and society are unknown. Greenland ice core records show that the eruption occurred in winter 852/3 ± 1 CE and that the eruption is associated with a relatively moderate sulfate aerosol loading but large abundances of volcanic ash and chlorine. Here we assess the potential broader impact of this eruption using palaeoenvironmental reconstructions, historical records and climate model simulations. We also use the fortuitous timing of the 852/3 CE Churchill eruption and its extensively widespread tephra deposition of the White River Ash (east) (WRAe) to examine the climatic expression of the warm Medieval Climate Anomaly period (MCA; ca. 950–1250 CE) from precisely linked peatlands in the North Atlantic region. The reconstructed climate forcing potential of the 852/3 CE Churchill eruption is moderate compared with the eruption magnitude, but tree-ring-inferred temperatures report a significant atmospheric cooling of 0.8 ∘C in summer 853 CE. Modelled climate scenarios also show a cooling in 853 CE, although the average magnitude of cooling is smaller (0.3 ∘C). The simulated spatial patterns of cooling are generally similar to those generated using the tree-ring-inferred temperature reconstructions. Tree-ring-inferred cooling begins prior to the date of the eruption suggesting that natural internal climate variability may have increased the climate system's susceptibility to further cooling. The magnitude of the reconstructed cooling could also suggest that the climate forcing potential of this eruption may be underestimated, thereby highlighting the need for greater insight into, and consideration of, the role of halogens and volcanic ash when estimating eruption climate forcing potential. Precise comparisons of palaeoenvironmental records from peatlands across North America and Europe, facilitated by the presence of the WRAe isochron, reveal no consistent MCA signal. These findings contribute to the growing body of evidence that characterises the MCA hydroclimate as time-transgressive and heterogeneous rather than a well-defined climatic period. The presence of the WRAe isochron also demonstrates that no long-term (multidecadal) climatic or societal impacts from the 852/3 CE Churchill eruption were identified beyond areas proximal to the eruption. Historical evidence in Europe for subsistence crises demonstrate a degree of temporal correspondence on interannual timescales, but similar events were reported outside of the eruption period and were common in the 9th century. The 852/3 CE Churchill eruption exemplifies the difficulties of identifying and confirming volcanic impacts for a single eruption, even when the eruption has a small age uncertainty.

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Section: Testate Amoebae Peatland Water Table Depth (Ie Summer Effect...mentioning

confidence: 99%

Section: Testate Amoebae Peatland Water Table Depth (Ie Summer Effect...mentioning

confidence: 99%

The 852/3 CE Mount Churchill eruption: examining the potential climatic and societal impacts and the timing of the Medieval Climate Anomaly in the North Atlantic region

et al. 2022

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“…Major changes in hydrological conditions have also been documented in many northern peatlands during the past millennium, coinciding with the transition from the milder Medieval Climate Anomaly (MCA) to the colder Little Ice Age (LIA) period (e.g. Mackay et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Widespread recent ecosystem state shifts in high‐latitude peatlands of northeastern Canada and implications for carbon sequestration

Magnan

Sanderson

Piilo

et al. 2021

Global Change Biology

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Northern peatlands are a major component of the global carbon (C) cycle. Widespread climate-driven ecohydrological changes in these ecosystems can have major consequences on their C sequestration function. Here, we synthesize plant macrofossil data from 33 surficial peat cores from different ecoclimatic regions, with high-resolution chronologies. The main objectives were to document recent ecosystem state shifts and explore their impact on C sequestration in high-latitude undisturbed peatlands of northeastern Canada. Our synthesis shows widespread recent ecosystem shifts in peatlands, such as transitions from oligotrophic fens to bogs and Sphagnum expansion, coinciding with climate warming which has also influenced C accumulation during the last ~100 years. The rapid shifts towards drier bog communities and an expansion of Sphagnum sect. Acutifolia after 1980 CE were most pronounced in the northern subarctic sites and are concurrent with summer warming in northeastern Canada. These results provide further evidence of a northward migration of Sphagnum-dominated peatlands in North America in response to climate change. The results also highlight differences in the timing of ecosystem shifts among peatlands and regions, reflecting internal peatland dynamics and varying responses of vegetation communities. Our study suggests that the recent rapid climate-driven shifts from oligotrophic fen to drier bog communities have promoted plant productivity and thus peat C accumulation. We highlight the importance of considering recent ecohydrological trajectories when modelling the potential contribution of peatlands to climate change. Our study suggests that, contrary to expectations, peat C sequestration could be promoted in high-latitude non-permafrost peatlands where wet sedge fens may transition to drier Sphagnum bog communities due to warmer and longer growing seasons.

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“…The rotifer Habrotrocha angusticollis is an important part of the soil microfauna found in wet Sphagnum mossy peatlands (Warner and Chengalath 1991). Examples on the richness of protozoa, often referred to as testaceans or thecamoeba, can be found in the work of Lamarre et al (2013), Amesbury et al (2018), , and Mackay et al (2021).…”

Section: Peatland Distribution and Extentmentioning

confidence: 99%

Global Peatlands Assessment: The State of the World’s Peatlands - Evidence for Action toward the Conservation, Restoration, and Sustainable Management of Peatlands

2022

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The goal of this assessment is to inform and inspire action in policy, research and practice that can help to protect, restore and sustainably manage peatlands now and long into the future. It provides a global overview of the current state, extent, governance and contributions to people of peatlands and of the drivers of peatland ecosystem change. Drawing on the best available science, the assessment is designed to help decision makers plan for sustainable peatland management and to mobilize and inspire peatlands conservation and restoration action at scale and at speed.

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Spatial variation of hydroclimate in north-eastern North America during the last millennium

Cited by 7 publications

References 89 publications

The 852/3 CE Mount Churchill eruption: examining the potential climatic and societal impacts and the timing of the Medieval Climate Anomaly in the North Atlantic region

The 852/3 CE Mount Churchill eruption: examining the potential climatic and societal impacts and the timing of the Medieval Climate Anomaly in the North Atlantic region

Widespread recent ecosystem state shifts in high‐latitude peatlands of northeastern Canada and implications for carbon sequestration

Global Peatlands Assessment: The State of the World’s Peatlands - Evidence for Action toward the Conservation, Restoration, and Sustainable Management of Peatlands

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