DOI: 10.5443/11357
title: Paleo-perspectives on environmental change in the high Arctic: the Canadian Contribution

description: Background: The snow and ice of the polar regions contain a wealth of information on the variability of the Earth¿s climate, past and present, and atmospheric composition. Many of the chemical compounds and aerosols found in the atmosphere find their way to the Arctic and are retained by the snow. Within large ice caps and ice sheets, annual snow layers accumulate. At depth, these layers are transformed into ice; preserving in the process much of their environmental signature. Thus, through ice core analysis, a glimpse of the pre-industrial atmosphere is offered, allowing us to place recent changes into perspective. Objectives: This project consists of three sub-projects which are closely linked in theme and method. Collectively, their aim is to document and reconstruct short and long term changes in climate and atmospheric contaminant deposition in the Canadian Arctic and neighbouring regions by analysing snow and ice cores. 1. Trends in the distribution of anthropogenic contaminants in the circumpolar region, is to conduct a pan Arctic survey of Arctic snow in order to quantify present levels and rates of accumulation of airborne contaminants. This activity is associated with the internationally approved COPOL program (IPY # 175) and with two Environment Canada-led IPY programs: (1) OASIS-CANADA: Understanding Ozone and Mercury in the Air Over the Arctic Ocean and (2) Pollutants Travelling in the Air to the Arctic. 2. Paleo-perspectives on environmental change in the High Arctic is closely associated to the study described above. The aim is to extend the record of atmospheric mercury and trace metals by sampling snow from a deep pit and from firn cores. Also included in this study the measurement of melt features observed in the snow. 3. Greenland Ice Sheet reactions to past and present climate change is to further explore the links between trace elements, pollen assemblages, and climate - particularly during glacial, interglacial, and transitional periods. To that end, we have joined the large-scale, multi-national, ice coring program: North Greenland Eemian Ice Drilling (NEEM). Rationale: The results of the project are important to the study of long-range / transboundary dispersion of airborne contaminants in the Arctic, thus, to the health of Northerners. Also to improve our understanding of the physical processes that control the transfer of Hg and methyl mercury (MeHg) from snow to aquatic ecosystems in glacierized basins.
description: Purpose: The results of the project are important to the study of long-range / transboundary dispersion of airborne contaminants in the Arctic, thus, to the health of Northerners. One specific objective is to define the baseline fluxes of Hg deposited from the atmosphere in the Arctic and to refine estimates of the net accumulation rates of Hg in snow from airborne sources and long-range transport. On Baffin Island, another goal associated with the project, is to improve our understanding of the physical processes that control the transfer of Hg and methyl mercury (MeHg) from snow to aquatic ecosystems in glacierized basins. The results are also important for the study of climatic change and its drivers, dynamics, and impacts. For example, the NEEM project, is expected to produce the first, undisturbed, ice core record from Greenland. This ice core will cover the last interglacial period including both the onset and decline. This climatic interval is of direct relevance to modern concerns. It may well provide a good approximation of a warmer future with higher sea levels and, possibly, a much smaller Greenland Ice Sheet.
description: Summary: Through the analysis of ice cores and snow samples and comparison with results of similar surveys completed in the 1990s, this project is documenting changes in climate and trends and levels of atmospheric contaminant deposition in the Canadian Arctic and adjacent regions. Researchers have measured the deposition of atmospheric contaminants such as sulphates, nitrates, mercury and other trace metals in snow and have found a significant drop in concentrations since the 1990s. At the same time, pollen concentrations have been increasing, and related glacier-monitoring studies have shown an increase in summer ice melt. In collaboration with researchers in Greenland, ice core samples are being collected to provide the first undisturbed ice core record of the last interglacial period which ended about 115,000 years ago, providing further data on climate and contaminant change over time.