Earth system feedbacks following large-scale tropical forest restoration (code & data)

Published: 18-08-2020| Version 1 | DOI: 10.17632/j39bw4rzsr.1
Alexander Koch


To achieve the Paris Agreement requires aggressive mitigation strategies alongside negative emission technologies. Recent studies suggest that increasing tree cover can make a substantial contribution to negative emissions, with the tropics being the most suitable region from a biogeophysical perspective. Yet these studies typically do not account for subsequent carbon cycle and climate feedback processes of large-scale land use change. Here we quantify the maximum potential temperature and CO 2 benefits from pantropical forest restoration, including earth system feedbacks, using a fully-coupled, emission-driven Earth System Model (HadGEM2-ES). We perform an idealised experiment where all land use in the tropics is stopped and vegetation is allowed to recover, on top of an aggressive mitigation scenario (RCP 2.6). We find that tropical restoration of 1529 Mha increases carbon stored in live biomass by 130 Pg C by 2100 CE. Whilst avoiding deforestation and tropical restoration in the tropics removes 42 Pg C compared to RCP 2.6, feedback processes mean that carbon in the atmosphere only reduces by 18 Pg C by 2100. The resulting, small CO 2 (9 ppm) benefit does not translate to a detectable reduction in global surface air temperature compared to the control experiment. The greatest carbon benefit is achieved 30–50 years after restoration before the Earth System response adjusts to the new land-use regime and declining fossil fuel use. We conclude that forest restoration can reduce peak CO2 mid-century, but can only be a modest contribution to negative emissions. This data is extracted from two 94-year long HadGEM2-ES simulations under RCP 2.6 (control) and RCP 2.6 but no anthropogenic land use in the tropics (restor) . The "code" section contains an R script to plot all parts of the carbon cycle (CC.csv in /data) as well as gives an overview on the extraction procedure. Further time series variables (land cover, temperature, precipitation, evapotranspiration/latent heat, and albedo) are available in /data. The original model data in netCDF format can be obtained from the author.