Several recent reports produced by the Intergovernmental Panel on Climate Change (IPCC) discuss the role of forests in the climate system. The IPCC Special Report on 1.5OC speaks of the potential of forests to take up CO2 and concludes that substantial afforestation efforts (with a potential of up to 3.6 GtCO2 yr−1, medium confidence) would be required in pathways limiting global warming to 1.5°C with limited or no overshoot. At the same time, the IPCC special report on land approved in August 2019 concludes that at the deployment scale of several GtCO2 per year the adverse side effects for adaptation, desertification, land degradation and food security would be expected with a high degree of confidence. But do we understand well what is the total footprint of the forest? There is an increase in greening observed from the satellites which demonstrate the fertilization effect, but forests are not only taking up CO2, they are also sources of methane and reactive constituents that impact climate on a short term.
The proposed great debate will address different opinions on the mitigation potential of forests.