Recherche

Propre aux climats froids, le pergélisol désigne un sol dont la température se maintient au-dessous de 0 °C pendant plus de deux années consécutives. Sa profondeur atteint généralement plusieurs dizaines ou centaines de mètres. Le pergélisol est gelé depuis des siècles ou des millénaires. Au cours de la fonte, le pergélisol change radicalement, comme on le comprend d’emblée en voyant la différence entre le sol gelé comme du béton et la boue molle et humide ou liquéfiée. Les interactions complexes et à long terme entre le climat, la géologie et l’écologie déterminent la température du sol et la teneur en glace, ce qui rend les prévisions difficiles. Contrairement à la neige ou à la végétation, il n’est pas facile d’observer le pergélisol à partir de satellites ou d’aéronefs, puisqu’il est dissimulé sous la couche active, couche supérieure du sol qui dégèle chaque été.

Le changement climatique provoque la fonte du pergélisol en raison d’une augmentation de la température atmosphérique et de modifications du régime des précipitations. La température de l’air au Canada, au nord du 60e parallèle, s’est accrue de 2,2 ºC entre 1948 et 2013 (trois fois la moyenne mondiale) et les précipitations ont également augmenté. De mémoire d’homme ou depuis le début de la dernière glaciation il y a environ 120 000 ans, les tendances et les conditions dans le Nord canadien sont sans précédent. La fonte du pergélisol ̶ dégel graduel de la glace souterraine ̶ provoque des changements importants dans le comportement du sol, comme la perte de solidité, et peut perturber les systèmes naturels et le cadre bâti. La fonte peut entraîner des affaissements en terrain plat, mais aussi des glissements de terrain sur les pentes. Le changement climatique et les perturbations provoquées par le développement ou les feux de forêt interagissent et amplifient souvent leurs effets mutuels sur l’état du pergélisol. La fonte du pergélisol, imputable à la chaleur latente élevée de la fusion de la glace, est bien plus lente que le réchauffement du sol sans glace. Dès lors, les conséquences de la perte graduelle de glace souterraine persisteront pendant des décennies, voire des siècles, à de nombreux endroits. La fonte généralisée du pergélisol entraîne également la libération de gaz à effet de serre provenant du carbone actuellement piégé dans le sol gelé, intensifiant encore davantage le réchauffement climatique.

De nombreux organismes canadiens ont pour mandat de générer, de mobiliser ou d’utiliser les connaissances sur le pergélisol. Mentionnons entre autres les commissions géologiques territoriales et la Commission géologique du Canada (CGC), Transports Canada et les ministères territoriaux du Transport, Environnement et Changement climatique Canada (ECCC), le Centre canadien de cartographie et d’observation de la Terre (CCCOT), Savoir polaire Canada, les instituts et collèges de recherche nordique, les organisations autochtones, les offices des terres et des eaux ainsi qu’un large éventail d’industries et de sociétés. Le pergélisol, sur lequel les données sont par nature rares mais évoluent aussi rapidement, requiert une recherche coordonnée et un partenariat à l’échelle du pays pour générer des connaissances pertinentes et les transposer en mesures efficaces. En mettant l’accent sur l’intégration des données, la synthèse et les prévisions, PermafrostNet CRSNG regroupera les connaissances, intensifiera les efforts à l’échelle du pays et élaborera les méthodes et techniques novatrices pour le traitement de données et les prévisions dont les Canadiens ont besoin.

This network’s contribution is conceptualized in a risk-reduction framework where responsible development—fiscally, environmentally and socially—includes adaptation planning for anticipated change. Permafrost thaw affects risk via hazards and exposure and, where driven by climate change, this is beyond our immediate control. Development affects exposure and vulnerability and can additionally change risk via permafrost thaw. Better permafrost and adaptation knowledge can reduce risk by enabling responsible development. Because of climate change, permafrost and adaptation knowledge must include future scenarios. 

1. Quantify, understand and predict permafrost thaw and its consequences. This gap exists because global climate change was not of concern when the foundation of permafrost science was established by researchers several decades ago.
2. Connect spatial scales from individual sites to national-scale prediction and assessment and from field measurements to satellite-based remote sensing and Earth-system modeling. This is important because corresponding knowledge and capabilities are currently part of scientific disciplines that are poorly connected with permafrost science.
3. Prototype reliable and useful data and knowledge products for stakeholders and develop relevant next practices with them. This gap exists because insufficient linkages exist between new scientific research, engineering and application of new knowledge in government, communities and industry.

1. Characterisation of permafrost. This theme will improve the understanding of ground-ice loss and its consequences though better characterisation of permafrost in the field and in laboratories so that prediction can better represent processes during thaw and have relevant subsurface input such as ground-ice content.
2. Monitoring of permafrost change. This theme will reveal and quantify permafrost change in Canada and contribute to understanding its varying rates and expressions at the land surface.
3. Prediction of permafrost change. This theme will improve the accuracy and delivery of transient permafrost simulation based on climate data, remote sensing and novel subsurface data so that the model results can support stakeholder needs at local and national scales.
4. Hazards and impacts associated with permafrost thaw. This theme will elucidate the relevance and the controls of permafrost hazards and thaw-induced impacts. Furthermore, it will improve their prediction to support adaptation decisions based on avoiding exposure and reducing vulnerability.
5. Adaptation to permafrost thaw. This theme will assist northern communities, governments and industry to plan for and manage the changing permafrost environment by providing specific strategies to minimise permafrost thaw and to reduce exposure and vulnerability of infrastructure.

1. Data products that will be useable for stakeholders and include interoperable databases of permafrost observations from field and laboratory as well as predictions of permafrost characteristics, change and resulting hazards. This is valuable because it enables a new class of evidence-based adaptation, for example by providing ensemble scenarios of likely future permafrost change.
2. Synthesis reporting on observed and anticipated permafrost change. The diversity and critical mass of the network offer a unique chance to synthesise insight gained from observations and simulations, to put them into a wider societal and scientific context and to identify critical gaps in knowledge and capabilities. This is valuable because more accurate and nuanced knowledge and communication of permafrost change in Canada will enable better decisions.
3. Next practices. We will report on the next practices that arise across themes from the experience gathered in applying novel methods or data and taking new approaches to practical problems in a multi-sectorial context. This is valuable because it supports the translation of new knowledge and experience into application beyond the network.

1. Understanding. The network will produce new insight into the behavior of frozen soil during thaw, the distribution of ground ice and the relationships connecting climate, infrastructure, permafrost thaw and observable impacts. This has value because it provides an improved foundation for permafrost research and engineering in a warming world, where permafrost can no longer be considered to be stable. Benefits for participants arise from early access to new knowledge that will allow to better address permafrost thaw, for example, through improved engineering design and land-use planning. Because more than one-third of Canada’s landmass is underlain by permafrost, there is significant intrinsic value in understanding the pervasive and persistent transformations of its Arctic landmass.
2. Methods. The network will produce novel methods and techniques for measuring and simulating thawing permafrost and for inferring or predicting permafrost characteristics for the present day and for future climate scenarios. This has value because methods and tools are important for translating knowledge into action in response to different environmental configurations and contexts. The exploitation of new capabilities will be accelerated by next practices that will evolve in the network. Benefits for participants arise from early access to novel methods that open up new possibilities for research and for addressing challenges of importance to stakeholders.
3. Experts. Network participants will face new challenges and innovate pathways to their solutions. In addition to discipline-specific education, network HQP will have familiarity with multiple scientific disciplines, understand applied problems related to permafrost and have novel skills in data science and computer simulation. Many will gain awareness of the complementarity of Indigenous ways of knowing and the importance of reciprocity in guiding how research is planned, conducted and delivered. This has value because stakeholders need new and multi-talented permafrost experts who can investigate, assess and design for permafrost thaw. This is mostly a new field of research and the network will produce and elevate a new cohort of early and mid-career scholars at a time when many preeminent permafrost scholars in Canada are nearing retirement. Expertise is also generated in partner organisations though the differentiated involvement of strategic management, permafrost scientists and experts in Indigenous communities and agencies.
4. Community. The network will add cohesion and reduce fragmentation in the Canadian permafrost community through shared understanding of challenges and the contributions that individual researchers, organisation or disciplines can make towards their solution. The strengthened interactions connecting individuals and organisations involved in research, engineering and practice have value because they empower northern communities and agencies, or those focused on northern issues, to better manage future development and climate adaptation. It also improves academic research and discovery through new research questions and hypotheses developed based on stakeholder needs. The benefits for network participants derive from a broadened research and training environment.