Constrained estimates of externally forced past and future warming for Canada
Date
2025
Authors
Li, Tong
Zwiers, Francis W.
Zhang, Xuebin
Wang, Xiaolan
Journal Title
Journal ISSN
Volume Title
Publisher
Earth's Future
Abstract
The Arctic has experienced the most rapid warming on Earth in recent decades. This affects Canada's landmass, which extends well into the Arctic. Nevertheless, limited spatial and temporal observational coverage, combined with large climate model uncertainties, pose challenges to understanding both past and future climate changes in these regions relative to preindustrial conditions. This is particularly challenging in a place like Canada that has insufficient historical data to determine preindustrial reference conditions. Emergent constraints can overcome this limitation by using historical observations for the modern post‐industrial era to constrain estimates of both preindustrial reference levels and future warming. Here we apply a carefully tested Bayesian observational constraint method to simultaneously assess the externally forced historical and future warming in Canada. Testing indicates that the approach reduces bias and uncertainty in historical and future warming estimates, increasing confidence that it may also serve as a basis for developing a broader understanding of climate change in other high‐latitude regions. We estimate that external forcing from human activity, has warmed Canada by 2.2 [1.3, 3.1]°C between the 1850–1900 pre‐industrial period and the recent 2015–2024 decade. Applying these same observational constraints to future climate conditions indicates that Canada will warm to 5.1 [3.2, 7.0]°C above pre‐industrial levels by the end‐of‐century under an intermediate emissions scenario SSP 2‐4.5, and to 6.7 [4.6, 8.9]°C under a high‐emissions scenario SSP 3‐7.0, with the largest warming projected for Northern Canada, followed by Quebec.
Description
Keywords
UN SDG 13: Climate Action, #journal article, Pacific Climate Impacts Consortium (PCIC)
Citation
Li, T., Zwiers, F. W., Zhang, X., & Wang, X. (2025). Constrained estimates of externally forced past and future warming for Canada. Earth's Future, 13, e2025EF006374. https://doi.org/10.1029/2025EF006374