Carbon farming in hot, dry coastal areas: an option for climate change mitigation

Abstract

Abstract. We present a comprehensive, interdisciplinary project which demonstrates that large-scale plantations of Jatropha curcas – if established in hot, dry coastal areas around the world – could capture 17–25 t of carbon dioxide per hectare per year from the atmosphere (over a 20 yr period). Based on recent farming results it is confirmed that the Jatropha curcas plant is well adapted to harsh environments and is capable of growing alone or in combination with other tree and shrub species with minimal irrigation in hot deserts where rain occurs only sporadically. Our investigations indicate that there is sufficient unused and marginal land for the widespread cultivation of Jatropha curcas to have a significant impact on atmospheric CO2 levels at least for several decades. In a system in which desalinated seawater is used for irrigation and for delivery of mineral nutrients, the sequestration costs were estimated to range from 42–63 EUR per tonne CO2. This result makes carbon farming a technology that is competitive with carbon capture and storage (CCS). In addition, high-resolution simulations using an advanced land-surface–atmosphere model indicate that a 10 000 km2 plantation could produce a reduction in mean surface temperature and an onset or increase in rain and dew fall at a regional level. In such areas, plant growth and CO2 storage could continue until permanent woodland or forest had been established. In other areas, salinization of the soil may limit plant growth to 2–3 decades whereupon irrigation could be ceased and the captured carbon stored as woody biomass.