A Holocene paleoclimate reconstruction for eastern Canada based on δ 18 O cellulose of Sphagnum mosses from Mer Bleue Bog

Abstract

We present a ~9200 yr high-resolution oxygen isotope record of plant cellulose (δ¹⁸O_cel) 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 δ¹⁸O_cel of Sphagnum follows the general pattern of the Northern Hemisphere reconstructed paleotemperature record for the last 2000 years at a ratio of ~2‰δ¹⁸O_cel/°C. The δ¹⁸O_cel 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 δ¹⁸O_cel 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 δ¹⁸O_cel 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.