A Holocene paleoclimate reconstruction for eastern Canada based on δ¹⁸O cellulose of Sphagnum mosses from Mer Bleue Bog

Abstract

We present a ~9200 yr high-resolution oxygen isotope record of plant cellulose (δ18Ocel) from the peat deposits of Mer Bleue Bog, Ontario and apply it as a proxy for paleotemperature reconstruction in Eastern Canada. The results show that δ18Ocel of Sphagnum follows the general pattern of the Northern Hemisphere reconstructed paleotemperature record for the last 2000 years at a ratio of ~2‰δ18Ocel/°C. The δ18Ocel record of ombrotrophic phase of Mer Bleue Bog is also in accordance with major features of the Holocene sunspot number reconstruction. Three distinct time intervals have low δ18Ocel values: 200–800 cal. BP (‘Little Ice Age’); 2800–3400 cal. BP synchronous to a cooling period reported elsewhere in North America; and 4200–4600 cal. BP corresponding to a cooling interval in the North Atlantic region. These cooling periods also correlate well with negative excursions in the Holocene sunspot and cosmogenic 10Be records. A fourth period of low δ18Ocel values between ad 1810 and 1820 may be related to the extremely cold summer of 1816 and cooler subsequent years, which occurred in the aftermath of the Tambora volcanic eruption, or possibly cooling associated with the early 19th century Dalton solar minimum. The results also indicate the presence of millennial-scale cycles possibly comparable with the globally recognized Bond cycles that have been correlated to fluctuations in solar irradiance.

Environmental and taxonomic controls of carbon and oxygen stable isotope composition in <i>Sphagnum</i> across broad climatic and geographic ranges

“…How well oxygen isotopes in Sphagnum tissues reflect atmospheric water or plant surface water depend on local weather conditions such as precipitation, air temperature and humidity. For example, Bilali et al (2013) suggest that oxygen isotopes in Sphagnum mosses from maritime bogs will track variation in precipitation patterns whereas isotopic values in continental habitats will be more dependent on summer temperature, as temperature and humidity are more variable in those regions. At local scales, oxygen isotope values also vary as a function of temperature and humidity.…”

Environmental and taxonomic controls of carbon and oxygen stable isotope composition in <i>Sphagnum</i> across broad climatic and geographic ranges

“…The modelled δ 18 O signal in meteoric water (precipitation) (Bowen and Wilkinson, 2002) was obtained from http:// www.waterisotopes.org (last access: 2 October 2017) as annual and monthly isotope ratio estimates at 10 arcmin resolution. These global estimates have shown to be highly accurate (R 2 = 0.76 for mean annual δ 18 O in precipitation) and are based on absolute latitude and elevation and account for regional effects on atmospheric circulation patterns (for details see Bowen, 2010Bowen, , 2017IAEA/WMO, 2015). To test which temporal period of δ 18 O values in precipitation showed the highest correlation with tissue δ 18 O values, we calculated annual (January-December), growing season (May-October) and winter-spring (January-April) mean isotope ratio.…”

“…Oxygen isotope composition has, therefore, been used to reconstruct climatic conditions and to infer the dominant water source in peatlands (Aravena and Warner, 1992;Ellis and Rochefort, 2006;van der Knaap et al, 2011). Ongoing measurements of oxygen isotopes in precipitation across the globe (Bowen, 2010;IAEA/WMO, 2015) have generated models that predict spatial patterns in oxygen isotope composition of precipitation based on temperature, elevation, atmospheric residence time and circulation patterns (e.g. Bowen, 2010).…”

“…Ongoing measurements of oxygen isotopes in precipitation across the globe (Bowen, 2010;IAEA/WMO, 2015) have generated models that predict spatial patterns in oxygen isotope composition of precipitation based on temperature, elevation, atmospheric residence time and circulation patterns (e.g. Bowen, 2010). Once isotopic composition of the source water is accounted for, variation in moss tissue isotopic values should be largely determined by fractionation that accompanies evaporation from the surface of plants.…”

A 9600‐year record of water table depth, vegetation and fire inferred from a raised peat bog, Prince Edward Island, Canadian Maritimes

“…In eastern Canada, peat-based paleoclimate research has been expanding over the last decade (e.g. Magnan et al, 2012El Bilali et al, 2013;Hughes et al, 2006;Van Bellen et al, 2012), although there are still many areas, such as the Maritime Provinces, where records are relatively sparse (although see Hughes et al, 2006;Robichaud and B egin, 2009;Charman et al, 2015).…”