Themes

1) Hydrological processes and freshwater availability

Unprecedented warming and human disturbance in the zone of discontinuous permafrost has led to substantial permafrost thaw in recent years. This has the potential to greatly alter the nature of water cycling within, and the volume and timing of runoff from the wetland-dominated drainage basins that characterize much of the discontinuous permafrost zone in the Northwest Territories (NWT) and elsewhere. The uncertainty regarding the mechanisms and rates of permafrost thaw, the impact of this thaw on water drainage and storage patterns and processes, and appropriate mitigation strategies, underscores the need for scientific research to provide the knowledge base required for informed and sustainable management of this resource. In response to this need, much of our research is focused on developing a new suite of models for predicting the response of discontinuous permafrost to climate warming and human disturbance (e.g. from oil and gas exploration, forestry, mining) and the consequent change in landcover and river flow regime in the Taiga Plains. This is being achieved by 1) developing new conceptual and mathematical models of water flow and storage processes; 2) developing a new permafrost thaw model that includes the effects of human-induced disturbances, and feedbacks from thaw-induced changes in ecology; and 3) by coupling the hydrological and permafrost-thaw models to predict the spatial distribution of permafrost and river flow regimes under possible scenarios of climate change and human-induced disturbances.

2) Permafrost thaw and ecosystem change

At high latitudes, permafrost conditions are fundamental to the ecology of boreal and tundra ecosystems. As such, the rapid warming and associated changes in permafrost conditions directly impact the composition, health and function of ecological communities. However, these communities in turn directly impact water and energy balances of the system resulting in complex interactions between climatic, hydrological, and ecological responses of ecosystems to warming. The Taiga Plains Ecoregion is ideally suited for the study of ecosystem responses to climate warming since it covers >50% of the NWT continental land mass over a wide latitudinal range, and therefore includes a wide range of permafrost characteristics. Furthermore, this region is home to a large proportion of the Northwest Territories’ population thus understanding the implications of climate warming-related changes in this region is critical for successful climate change adaptation planning in the NWT. Widespread ecosystem changes occurring as a consequence of climate warming and human disturbance, include but are not limited to: permafrost thaw-induced conversion of forests to wetlands on discontinuous permafrost and a greening of the tundra via shrub expansion promoted by active layer warming and thickening on continuous permafrost. Ongoing efforts include (1) the quantification of boreal forest responses to permafrost thaw across latitudes and examination of the mechanism underlying these responses; and (2) interactions between permafrost conditions and natural disturbance agents in determining the distribution, structure, and function of vegetation communities.

3) Carbon flux and atmospheric monitoring

A large portion of Canada’s northern landscapes has permanently frozen ground (permafrost) that thaws seasonally at the top over a short growing season.  Recent northern research suggests an increase in active-layer thickness (ALT) in the continuous permafrost zone and degradation of the discontinuous permafrost zone into seasonally frozen ground in response to an increasingly warmer climate. Increasing ALT and/or continued permafrost degradation will have far-reaching consequences for northern ecosystems including altered hydrology and the exposure of additional soil organic C to microbial decomposition (e.g., increased emissions of carbon dioxide [CO₂] and/or methane [CH₄] to the atmosphere à positive feedback). In contrast, potential consequences might also cause fundamental changes in vegetation composition and structure, which might constitute a negative feedback by altering important land surface characteristics (e.g., increase in albedo à land surface cooling). Substantial uncertainties exist regarding direction and magnitude of the net feedback to the climate system because of our incomplete understanding of the links between ALT and permafrost degradation, hydrology, vegetation, land surface properties, disturbance frequency and intensity, and CO₂ and CH₄ sink-source strengths.