NWT RESEARCH DATABASE

Regions: Inuvialuit Settlement Region, Gwich'in Settlement Area

Tags: physical sciences, hydrology, surface water, paleontology, peatlands, freshwater ecosystem, lake sediment

Objective(s): To reconstruct Late Holocene climate parameters and hydrology in the Mackenzie River Basin along a latitudinal gradient from the outflow of the Mackenzie River at Great Slave Lake to its discharge into the Arctic Ocean; to evaluate drivers of background variability identified in the proxy paleohydrological and paleoclimate datasets; to generate hydrological models to predict future changes in water quantity under warming scenarios; and to engage in two-way knowledge building and sharing among the research team, community members, decision makers, and stakeholders using web-enabled, open geoscience initiatives.

Project Description: This licence has been issued for the scientific research application No.4705. The Mackenzie River Basin (MRB) is one of the largest cold-water, intact boreal ecosystems in the world and has unique Earth-system’s processes associated with sea ice formation, global circulation of deep ocean currents, carbon storage, and biogeochemical cycling. This unique global resource is also critical for supporting northern communities through sustenance, as a cultural resource, transportation of goods and services, and has abundant natural resources, including an estimated 191 bb oil (Canol and Bluefish plays), oil sands, natural gas (Horn River), minerals (Pb, Zn, W), and hydroelectric potential. The stability and integrity of the unique cryospheric, hydrologic, ecologic, and climatological processes of the MRB are threatened by cumulative impacts of climate change and natural resource development. Water quantity monitoring of the MRB by project partner Environment and Climate Change Canada began in the early 1970s, but the brevity of instrumental records makes them insufficient for understanding multi-decadal cycles and trends associated with synoptic-scale climate phenomena, such as the Pacific Decadal Oscillation (PDO), and impacts on hydrology and ecosystems of the MRB. A millennial to centennial-scale perspective is thus necessary to interpret monitoring data and recent changes in a long-time context to accurately predict the magnitude of ecosystem response to current and forecasted climate change. This project team will develop and disseminate new knowledge on drivers of long-term climate change in the MRB and its impact on present and future water quantity. This knowledge is needed by governments, northern organizations, and communities to strategically and sustainably manage cumulative effects of climate change and natural resource development in the MRB. The research team will employ an innovative multi-disciplinary approach to reconstruct the climate of the past ~4000 years through detailed study of lake sediment and peatland archives using paleontology, sedimentology, and isotope, organic, element, and molecular geochemistry. Paleoecological data will be integrated with Traditional Knowledge (TK) (conducted by project partners Gwich'in Tribal Council Department of Cultural Heritage and T. Lantz) on past climate and water quantity, instrumental, and real-time monitoring data derived from existing citizen and community-based science platforms to form a knowledge assemblage of long-term variability of baseline hydrology, drivers of that variability, and associated impacts to terrestrial and aquatic ecosystems. Hydrological modelling rooted in the derived reconstructions will be used to generate predictions of future trajectories of climate variability and ecohydrological change in the MRB. The specific goals are: 1) to quantitatively and qualitatively reconstruct Late Holocene climate parameters and hydrology in the MRB along a latitudinal gradient from the outflow of the Mackenzie River at Great Slave Lake to its discharge into the Arctic Ocean, with a focus in the Gwich’in Settlement Area, using an integrated sub-decadal to centennial paleoecological, TK, and instrumental and monitoring approach. To achieve this the research team will develop transfer functions based on a suite of paleoecological proxy indicators to quantitatively reconstruct hydrological change and evaluate the impact of those changes on surface hydrology and chemistry. Proxies of hydrological and climate change evaluated in near surface sediments from ~100 lakes and a number of peatlands (~30) will form the basis of the transfer function training sets: particle size and end-member mixing analysis (EMMA) to reconstruct overland hydrology11 and testate lobose amoebae to quantitatively reconstruct water table depth in peatlands. The developed transfer functions will be applied to lake and peatland cores collected in the MRB that will be dated using 210Pb and AMS 14C and age-depth modelling. Using the cores, qualitative paleoclimate and paleohydrological change will be reconstruc ted based on plant macrofossil and palynological analyses to provide information on vegetation change and linkages to paleohydrology, including past permafrost dynamics. Element geochemistry using ITRAX-XRF sediment core scanning coupled with ICP-MS analysis of lake sediments and peat will be used to reconstruct paleo-surface water and sediment quality and conditions. Information on paleoproductivity, paleo-redox conditions, and linkages between organic matter, biogeochemical cycling, climate, and hydrology will be produced using HAWK pyrolysis, and solid and dissolved organic geochemistry of sediments. Groundwater contribution to watershed discharge, weathering rates, and sediment provenance associated with hydrological changes may be reconstructed using stable isotope and element geochemical analyses of the cores. TK on climate change and its environmental impacts has the potential to provide information on parameters not discernible using western science alone. Integration of data from field, physical, chemical, biological, and cultural research and instrumental monitoring data on long-term trends in water quantity of the MRB will be accomplished with the use of a weight of evidence approach for quantitative and qualitative data to combine, integrate, and weigh our data using statistical metrics (e.g., Bayesian methods); 2) to evaluate drivers of background variability identified in the proxy paleohydrological and paleoclimate datasets using time series analyses on climate and hydrological reconstructions to statistically define cycles and trends in the data. Spectral, wavelet, and cross-wavelet statistical comparison to published high-resolution and high-quality records of known climate phenomena (e.g., 10Be and 14C proxies of solar variability, PDO records) will be conducted; 3) to generate hydrological models to predict future changes in water quantity under current warming scenarios. These models will be based on our reconstructions and conducted using the DigiBog hydrological modelling suite to simulate and forecast hydrological dynamics in the MRB using time-series of downscaled paleoclimate estimates and the HadCM3 general circulation model; and, 4) to engage in two-way knowledge building and sharing among the research team, community members, decision makers, and stakeholders using web-enabled, open geoscience initiatives to ensure that our research is co-designed to meet the needs of northerners and other stakeholders throughout the life of the project. Generation of training opportunities (university, college, and community based) are a key component of our project. All materials and associated metadata will be curated in the permanent collections of the GSC and associated databases (e.g., SMS) and knowledge management frameworks of the federal government. Data will also be managed based on feedback from end-users, stakeholders, and partners and include existing frameworks (e.g., NWT Discovery Portal) where possible. Open geoscience will be a core initiative of our data and knowledge transfer strategy and will include open access to data through open-source published reports (e.g., GSC Open Files available on GEOSCAN; NWT Open Reports). Raw data will be synthesized and made publically available and shared with policy and regulatory groups to inform development of improved environmental quality guidelines and regulations in a format as requested by stakeholders. The knowledge transfer and communication strategy is co-designed with project partners to build and share knowledge among networked groups that include Indigenous organizations, northern communities, universities, and federal and territorial governments. The knowledge exchange strategy is designed to facilitate direct dialogue amongst researchers, Indigenous communities, HPQ, policy makers, and northerners through direct inclusion in the project team. This inclusive strategy will facilitate the two-way knowledge exchange needed to meet project objectives of improved decision making and policy by involved stakeholders as well as other end-users that may include DFO, INAC, Transport Canada, Canadian Environmental Assessment Agency, Mackenzie Valley Environmental Impact Review Board, Mackenzie Valley Land and Water Board, Sahtù Land and Water Board, Gwich’in Land and Water Board, Wek?èezhìi Land and Water Board, and Inuvialuit Water Board, Environmental Impact Review Board, Environmental Impact Screening Committee. The fieldwork for this study will be conducted from: August 1, 2020, to December 31, 2020.