Carbon Sequestration by Tropical Trees and Crops: A Case Study of Oil Palm

Carbon sequestration by photosynthetic organisms is the principal mechanism for the absorption of atmospheric CO2. Since the 1950s, however, the global carbon cycle has been distorted as increased anthropogenic CO2 emissions have greatly outstripped rates of carbon sequestration, with a 50% increase in atmospheric CO2 levels in less than a century, leading to perturbation of global climate systems and threatening food production and social stability. In order to address the current imbalance in CO2 flux, it is important to both reduce net emissions and promote sequestration. To address the latter issue, we need to better understand the roles of systems, such as natural forests, coastal wetlands, and tropical croplands, in carbon sequestration and devise strategies to facilitate net CO2 uptake. Carbon sequestration by tropical trees and crops already removes in excess of 1000 million tonnes of atmospheric CO2 annually but is threatened by anthropogenic activities such as deforestation and the drainage of carbon-rich peatland. Improvements in carbon sequestration can be achieved by policies such as growing tropical crops as part of agroforestry systems, enforcing limitations on deforestation and the use of peatland, and auditing the carbon impact of major cropping systems in order to focus on those crops that deliver both high yields and carbon efficiency. As an initial step in this process, a detailed case study is presented on the tropical tree crop, the African oil palm, Elaeis guineensis. This analysis includes a comparison of the carbon sequestration potential of oil palm with that of tropical forests and other oil crops, the biomass sequestration potential of oil palm and current and future strategies aimed at achieving net-zero carbon targets for oil palm and related crops.