Carbon removal capacity estimation of taiga reforestation and afforestation at the western boreal edge using spatially explicit carbon budget modeling

Abstract

Canada's northern boreal forest edge offers considerable potential for climate change mitigation through large-scale tree planting. Afforestation in these sparsely forested regions could assist the natural northward migration of forests while capitalizing on their carbon removal capacity. However, the sequestration potential is uncertain due to a lack of spatially explicit models. This study uses Monte Carlo estimates and a carbon budget model to quantify the carbon removal capacity of afforestation at the northwestern boreal edge from 2025 to 2100. We combined satellite inventory data and probabilistic fire regime representations to simulate total ecosystem carbon under scenarios considering fire return intervals, land classes, planting mortality, and climate variables. Our results indicate that afforesting ~6.4-32 million hectares could sequester ~3.88-19.4 Gigatonnes of CO2 e over the next 75 years, with the Taiga Shield West ecozone showing the most potential. Even the conservative estimate (3.88 Gt CO2 e) is over five times Canada's total annual greenhouse gas emissions, making it a substantial contribution toward the nation's 2050 net-zero goal. Further research is needed to refine these estimates, assess economic viability, and investigate impacts on regional processes like permafrost thaw and surface albedo.