Competing roles of rising CO₂ and climate change in the contemporary European carbon balance

Abstract. Natural ecosystems respond to, and may affect climate change through uptake and storage of atmospheric CO₂. Here we use the land-surface and carbon cycle model JULES to simulate the contemporary European carbon balance and its sensitivity to rising CO₂ and changes in climate. We find that the impact of climate change is to decrease the ability of Europe to store carbon by 97 TgC yr⁻¹. In contrast, the effect of rising atmospheric CO₂ has been to stimulate increased uptake and storage. The CO₂ effect is currently dominant leading to a net increase of 114 TgC yr⁻¹. Our simulations do not at present include other important factors such as land use and management, the effects of forest age classes and nitrogen deposition. Understanding this balance and its implications for mitigation policies is becoming increasingly important.