Project

Discipline

Sedimentology; Lake sediments; Microstratigraphy; Arctic2k; Limnogeology; Paleoclimatology; MicroXRF; Radiometric dating; Calibration in time; Arctic Oscillation

Lead
Le réchauffement global de la planète est un fait reconnu et sans précédent. L’Arctique, du fait de son extrême vulnérabilité, constitue un endroit privilégié à l’étude du réchauffement climatique. Afin de placer ce réchauffement sur le long terme, et de pouvoir l’attribuer à des causes naturelles (ex. activité solaire, éruptions volcaniques) et/ou humaines (ex. gaz à effet de serre), le recours aux données climatiques sur le passé (>150 ans) est nécessaire. Dans ce contexte, les lacs arctiques sont d’excellentes archives du paléoclimat. Au travers des sédiments qui se déposent en leurs fonds, ces lacs enregistrent les variations extrêmes de température, de précipitations, et du niveau de la mer selon les saisons. Bien que ces données soient très importantes pour l’étude du climat dans le passé, elles n’en demeurent pas moins très rares et difficiles à obtenir, du fait notamment de la difficulté d’accès aux lacs de cette région isolée.
Lay summary
Objectifs du travail de recherche À travers l’étude d’une carotte de sédiments d’un lac côtier de l’Arctique Canadien (Shellabear Lake, Melville Island), nous avons pour objectifs principaux de reconstruire le climat (températures et précipitations) ainsi que les changements du niveau de l’Océan Arctique sur les mille dernières années. Cet objectif final passe par trois étapes spécifiques de travail: (i) développer une chronologie fiable et précise de la carotte grâce à la présence de varves (=lamines annuelles de sédiments); (ii) déterminer l’origine de l’enrichissement en sel marin de Shellabear Lake; (iii) reconstruire le climat et les changements associés au niveau de l’Océan.   Contexte scientifique et social du projet de recherche Ce projet générera le premier enregistrement sédimentaire d’un lac hyper salin d’Arctique. Les résultats permettront de mieux comprendre: (i) la récente hausse de salinité des lacs arctiques; (ii) leur lien avec les changements du niveau de l’Océan Arctique; et (iii) les impacts du changement climatique et de l’inondation côtière.

Direct link to Lay Summary

Last update: 22.07.2015

Active participation

Communication	Title	Media	Place	Year

Title	Year

The Arctic is extremely sensitive to climate change, and an influential part of the global climate system. However, the assessment of climate change and impacts from the Arctic remains a challenge because meteorological records are short and sparse, and because natural and human-induced climate changes are difficult to separate.In this context, data from natural paleoclimate archives are fundamental to place climate variability into perspective and assess the sensitivity of Earth’s climate to natural and anthropogenic forcings. In particular, Arctic lakes are excellent archives. They are sensitive to more extreme seasonal variations in surface processes and have a limited direct human impact.Nevertheless, the study of Arctic lakes is a logistic, analytical and technical challenge because: (i) limnological information are often lacking in remote Arctic regions due to difficult accessibility; (ii) 210Pb fallout inventories are low and terrestrial macrofossils for 14C dating are rare, which limits the development of precise sediment chronologies; and (iii) sediment accumulation rates are extremely low, which may restrict the temporal resolution and length of the paleoclimate records.Here, through the present Early Postdoc.Mobility project, the applicant Dr. Amann proposes to overcome all these challenges by studying at high resolution the varved sediments (annual laminations) of a hypersaline coastal lake located in the Canadian High Arctic (Shellabear Lake; 74°50’N, 113°30’W). The aim of this project is to generate a high-resolution geochemical and mineralogical record together with a lithostratigraphical analysis of these varved sediments to reconstruct past sea-level changes, and to address questions related to past, present and future climate variability and change.The proposed project is divided in three Work Packages, three specific aims:•Aim 1 (Work Package 1): Develop a high-resolution chronology based on sedimentary facies and varve formation process understanding•Aim 2 (Work Package 2): Determine the onset of saline enrichment of Shellabear Lake and assess the impact of marine transgressions on the sediment biogeochemical properties •Aim 3 (Work Package 3): Assess a climate signal from sediment proxies and reconstruct past climatic variability for the past ca. 700 years.This Early Postdoc.Mobility project will provide the first sedimentary record from a hypersaline Arctic lake, which has broad importance and implications. It will help understand the salinity development of Arctic lakes and its link to marine transgressions in order to assess the impacts of future climate change, sea-level rise and coastal inundation. This study will contribute to the IGBP-PAGES Arctic2k Working Group and its proxy database.The proposed project will be carried out at the Research Laboratory ‘Environmental Variability and Extremes’ (EVEX) at the Department of Geography of Queen’s University in Kingston (Ontario, Canada), and supervised by Prof. Dr. Scott Lamoureux.Prof. Dr. Scott Lamoureux is recognized in the scientific community as a worldwide leading expert for microfacies and thin section analysis of varved lake sediments, and in properties of sediments that relate to changes in climatic and other environmental changes. The applicant will gain extensive new knowledge and experience from Prof. Dr. Scott Lamoureux, especially in microstratigraphy, µXRF, data interpretation and analysis (statistics), and automated field observations in remote places (hydrometeorology: weather stations and monitoring systems establishment). Further expertise will be gained in the collaboration with numerous leading scientists from Canada and North America; Prof. Dr. John Smoll, Prof. Dr. Peter Leavitt, Prof. Dr. Pierre Francus, Prof. Dr. Reinhard Pienitz, and Prof. Dr. Raymond Bradley, in particular.