Summary and synthesis of Changing Cold Regions Network (CCRN) research in the interior of western Canada – Part 2: Future change in cryosphere, vegetation, and hydrology
Authors: DeBeer Chris M. , Wheater Howard S. , Pomeroy John W. , Barr Alan G. , Baltzer Jennifer L. , Johnstone Jill F. , Turetsky Merritt R. , Stewart Ronald E. , Hayashi Masaki , van der Kamp Garth , Marshall Shawn , Campbell Elizabeth , Marsh Philip , Carey Sean K. , Quinton William L. , Li Yanping , Razavi Saman , Berg Aaron , McDonnell Jeffrey J. , Spence Christopher , Helgason Warren D. , Ireson Andrew M. , Black T. Andrew , Elshamy Mohamed , Yassin Fuad , Davison Bruce , Howard Allan , Thériault Julie M. , Shook Kevin , Demuth Michael N. , Pietroniro Alain 
Published: April 2021

Abstract. The interior of western Canada, like many similar cold mid- to high-latitude regions worldwide, is undergoing extensive and rapid climate and environmental change, which may accelerate in the coming decades.
Understanding and predicting changes in coupled climate–land–hydrological
systems are crucial to society yet limited by lack of understanding of changes in cold-region process responses and interactions, along with their representation in most current-generation land-surface and hydrological
models. It is essential to consider the underlying processes and base
predictive models on the proper physics, especially under conditions of
non-stationarity where the past is no longer a reliable guide to the future
and system trajectories can be unexpected. These challenges were forefront
in the recently completed Changing Cold Regions Network (CCRN), which
assembled and focused a wide range of multi-disciplinary expertise to
improve the understanding, diagnosis, and prediction of change over the cold interior of western Canada. CCRN advanced knowledge of fundamental cold-region ecological and hydrological processes through observation and
experimentation across a network of highly instrumented research basins and
other sites. Significant efforts were made to improve the functionality and
process representation, based on this improved understanding, within the
fine-scale Cold Regions Hydrological Modelling (CRHM) platform and the
large-scale Modélisation Environmentale Communautaire (MEC) – Surface
and Hydrology (MESH) model. These models were, and continue to be, applied
under past and projected future climates and under current and expected future land and vegetation cover configurations to diagnose historical
change and predict possible future hydrological responses. This second of
two articles synthesizes the nature and understanding of cold-region processes and Earth system responses to future climate, as advanced by CCRN. These include changing precipitation and moisture feedbacks to the
atmosphere; altered snow regimes, changing balance of snowfall and rainfall, and glacier loss; vegetation responses to climate and the loss of ecosystem resilience to wildfire and disturbance; thawing permafrost and its influence on landscapes and hydrology; groundwater storage and cycling and its connections to surface water; and stream and river discharge as influenced by the various drivers of hydrological change. Collective insights, expert elicitation, and model application are used to provide a synthesis of this change over the CCRN region for the late 21st century.