AFFORESTATION AND MITIGATION OF CLIMATE CHANGE: A MATHEMATICAL MODEL OF THE CARBON-CLIMATE SYSTEM

An energy balance model (EBM) is developed by augmenting a carbon-climate module found in DICE to include a land carbon pool in addition to three other pools. The land pool allows us to examine the impact of potential afforestation on future temperatures and associated damages. By removing CO2 from the atmosphere afforestation reduces global temperatures and thereby economic damages. Realistic and optimistic rates of afforestation are investigated for four scenarios of future CO2 emissions and per capita incomes derived from the IPCC’s shared socioeconomic pathways (SSP). The emission pathways are employed in our EBM to provide a path of future temperatures that tracks well with projections from SSPs. Since afforestation reduces atmospheric CO2 and thereby temperatures, and since economic damages are a function of temperature, sequestration of carbon in forests reduces damages and increase income. Under the SSP2 and SSP3 scenarios, afforestation has little impact on atmospheric CO2 and damages, and minimal impact under the SSP5 scenario. Impacts of afforestation are higher when using a Weitzman damage function as opposed to Nordhaus specification. CO2 removals by afforestation are very small relative to anthropogenic emissions to the atmosphere. Yet afforestation may provide substantial ecosystem service benefits and/or local climate mitigation benefits.