Climate and atmospheric drivers of historical terrestrial carbon uptake in the province of British Columbia, Canada

Abstract. The impacts of climate change and increasing atmospheric CO₂ concentration on the terrestrial uptake of carbon dioxide since 1860 in the Canadian province of British Columbia are estimated using the process-based Canadian Terrestrial Ecosystem Model (CTEM). Model simulations show that these two factors yield an enhanced carbon uptake of around 44 gC m⁻² yr⁻¹ (or equivalently 63 gC m⁻² yr⁻¹ over the province's forested area), during the 1980s and 1990s, and continuing into the 2000s. About three-quarters of the simulated sink enhancement in our study compared to pre-industrial conditions is attributed to changing climate, and the rest is attributed to increase in CO₂ concentration. The model response to changing climate and increasing CO₂ is corroborated by comparing simulated stem wood growth rates with ground-based measurements from inventory plots in coastal British Columbia. The simulated sink is not an estimate of the net carbon balance because the effects of harvesting, insect disturbances and land-use change are not considered.