Assessing the role of internal variability in the carbon budgets framework
- 1ETH Zurich, Institute for Atmospheric and Climate Science, Zurich, Switzerland (kasia.tokarska@env.ethz.ch)
- 2Canadian Centre for Climate Modelling and Analysis, Environment and Climate Change Canada, Victoria, BC, V8W 2P2, Canada
- 3CNRM, Université de Toulouse, Météo France, CNRS, Toulouse, France
Carbon budgets are a policy-relevant tool that provides a cap on global total CO2 emissions to limit global mean warming at the desired level, for example, to meet the Paris Agreement target. Internal variability due to natural fluctuations of the climate system affects the temperature and carbon uptake on land and in the ocean. However, uncertainties arising from internal variability have not been quantified in the Transient Climate Response on Cumulative Emissions (TCRE) framework and related carbon budgets. Here we show that even though land carbon uptake exhibits the highest internal variability, most of the uncertainty in TCRE and carbon budgets arises from the temperature component, in concentration-driven simulations. Resulting remaining carbon budgets for 1.5 and 2.0 °C temperature targets differ even up to ±10 PgC (± 36.7 GtCO2; 5-95% range), due to internal variability, which is approximately equivalent to one year of global annual CO2 emissions. Our results suggest that calculating carbon budgets directly from climate models’ output does not introduce significant biases in TCRE and remaining carbon budgets due to internal variability.
How to cite: Tokarska, K., Gillett, N. P., Arora, V. K., and Séférian, R.: Assessing the role of internal variability in the carbon budgets framework , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5361, https://doi.org/10.5194/egusphere-egu2020-5361, 2020