Canadian climate data portals: A comparative analysis from a user perspective

Climate data portals are essential tools for climate change adaptation. This study analyses differences between two Canadian portals providing bias-adjusted CMIP6 simulations: Climate Data Canada and Portraits Climatiques. The study evaluates three core variables (daily maximum temperature, daily minimum temperature and precipitation) as well as assesses five case studies, taken from the agriculture, transport and health sectors, that relied on climate indicators available through the portals. The underlying datasets vary in multiple ways (bias-adjustment methodology, climate of reference, ensemble composition, emissions scenarios) and, in general, the climatology of variables and indicators tends to be statistically different between portals towards the end of the century. Differences are significantly reduced when comparing projected changes with respect to present climate conditions, highlighting the important role played by the dataset used as a reference for the bias-adjustment procedure. When considered from the point of view of practical applications, the discrepancies between the portals are generally, although not always, sufficiently small that they do not impact the resulting decisions. Finally, indicators based on a fixed threshold were found to be strongly influenced by the reference used for the bias adjustment.