Research Project

Emissions scenarios consistent with the 1.5°C and 2°C temperature targets require negative emissions. These pathways are designed with an assumption of symmetry, that is, that each tonne of CO₂ emitted into the atmosphere can be offset by removing an equivalent amount of CO₂. Research shows that this assumption of symmetry does not hold for the carbon cycle and there is high uncertainty regarding the asymmetry of the temperature response. While the assumption of symmetry is a useful simplification for designing emissions scenarios, it has important implications for how effectively global climate targets can be achieved using negative emissions. Using symmetric simulations run in Earth system models of different complexities, I explore the asymmetry in the climate-carbon cycle response to positive and negative CO₂ emissions, focusing my analysis on land processes.