Multi-proxy approach to long- and short-term Holocene climate-change: evidence from eastern Lake Ontario

• Published in: Journal of paleolimnology Vol. 33; no. 3; pp. 371 - 391
• Main Authors: McFadden, Melany A., Patterson, William P., Mullins, Henry T., Anderson, William T.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01.04.2005
• Subjects: Anthropogenic factors; Carbon; Climate change; Deep water; Heat transport; Holocene; Lakes; Organic carbon; Organic matter; Proxies; Silica; Soils; Thermohaline circulation; North America, Ontario L
• ISSN: 0921-2728; 1573-0417
• DOI: 10.1007/s10933-004-7634-5

We use a multi-proxy (n = 11) paleolimnological approach on deep-water sediment from eastern Lake Ontario to characterize both long- and short-term regional climate change over the past ~10,000 calendar years. Proxies included % total organic matter, % total carbonate, magnetic susceptibility, C/N ratios, % organic carbon, % total nitrogen, % biogenic silica and δ^sup 18^O and δ^sup 13^C of carbonate, as well as δ^sup 13^C and δ^sup 15^N of bulk organic matter. There is a marked shift in most proxies at ~9.4 ka which defines the start of Holocene warmth in this region. Prior to this, the area was influenced by the post-Younger Dryas cold/wet interval, controlled by a southward displacement of the polar front jet stream, when many proxies were at their minimum. The Hypsithermal interval (~9.4-5.3 ka) was the warmest and wettest of the Holocene due to a long-term increase in summer insolation. The Hypsithermal, however, was interrupted by two cold climates; the 8.2 ka event (~8.4-8.0 ka) and the Nipissing Rise (~6.8-5.0 ka), both of which are linked to a reduction in thermohaline circulation and northward oceanic heat transport. The Neoglacial interval (~5.3 ka to ~1850 AD), driven by a long-term decrease in summer insolation, was cooler and dryer, but more stable, than the Hypsithermal. The short Historic interval (post ~1850 AD) was characterized by some of the largest amplitude and most abrupt anomalies of the past 10,000 years, due to intense anthropogenic activity, when a number of proxies reached unprecedented values.[PUBLICATION ABSTRACT]