Quantifying carbon cycle feedbacks under negative CO2 emissions

Land and ocean carbon sinks play a major role in regulating atmospheric CO2 concentration and climate. However, their future efficiency depends on feedbacks in response to changes in atmospheric CO2 concentration and climate. Since negative CO2 emissions technologies (NETs) are a key mitigation measure in emission scenarios consistent with global climate targets, understanding carbon cycle feedbacks under negative CO2 emissions is essential. This thesis investigates carbon cycle feedbacks under positive and negative CO2 emissions using an Earth system model driven with idealized scenarios of increasing and decreasing atmospheric CO2 concentration. Results suggest that carbon cycle feedbacks differ under positive and negative emissions, independently of the specific approach chosen for their quantification. The findings of this thesis provide insights into the approach best suited to quantify carbon cycle feedbacks under negative CO2 emissions, and into the role of these feedbacks in determining the effectiveness of NETs in reducing CO2 levels.