Late Holocene Environmental Change Across the Canadian Arctic

• Main Author: Tamo, Camille
• Format: Thesis
• Language: English
• Published: Université d'Ottawa / University of Ottawa 2019
• Subjects: paleoclimate; pollen; Arctic; diatoms; Little Ice Age; vegetation; Medieval Climate Anomaly; Common Era; Holocene; Nunavut; Ellesmere Island; Canadian Arctic Archipelago; Bathurst Island; Prince of Wales Island; Four Lakes; Arctic Archipelago; Banks Island
• Online Access: https://dx.doi.org/10.20381/ruor-23089; http://ruor.uottawa.ca/handle/10393/38837

Lake sediment cores spanning the last 2000 years from four sites across the Canadian Arctic Archipelago (CAA) document the responses of terrestrial and freshwater ecosystems to regional climate variability. Biogenic silica (BSi) records in cores from Banks Island, NWT (Lake B503; 72.3245, -123.4036, 84 masl), Bathurst Island, Nunavut (PR01; 75.6497, -99.1144, 30 masl), Prince of Wales Island, Nunavut (SW08; 72.3177, -97.2678, 104 masl), and Ellesmere Island, Nunavut (CV03; 79.9211, -82.9348, 363 masl) were used to examine the relationship between diatom production and climate. A pollen record from Prince of Wales Island provided the first high-resolution July temperature reconstruction for the last 1000 years for the central CAA. Dissolution was evident in three out of the four lakes; core SW08 contained no BSi above detection and cores CV03 and PR01 only contained values above detection in the uppermost sediments, suggesting that the preservation of biogenic silica (BSi) in the sediment is likely influenced by sedimentary carbonates. A BSi sequence from core B503 showed that diatom production was affected by climate changes such as the Medieval Climate Anomaly and the Little Ice Age. The vegetation on southern Prince of Wales Island underwent marked transitions during the Little Ice Age and Medieval Climate Anomaly, which was mainly observed in the proportion of Cyperaceae and Poaceae. The mean July temperature reconstruction showed a long-term cooling from 1080-1915 CE with a sustained cold period from 1800-1915 CE prior to 20th-century warming. A synthesis of paleoclimate records from across the Arctic demonstrated that pollen-based reconstructions record both high and low frequency climate variability, when sampling resolution is sufficient, and can improve regional climate reconstructions.