Climate Change Mitigation by Managing the Terrestrial Biosphere

Abstract

The terrestrial C pool, 3,900 Pg comprising of C in soil and the vegetation, is the third largest after the oceanic and the geological pools. Rather than with the on-set of the Industrial Revolution around 1800 AD, the Anthropocene may have commenced 10–12 millennia ago with the dawn of settled agriculture. Given this hypothesis, the terrestrial biosphere may have lost as much as 480 Pg C, of which 70–100 Pg may have been depleted from the world’s soils. Whereas most of the C emitted from the terrestrial biosphere may have been reabsorbed by the ocean and the land-based sinks, the depleted C pool created a C sink capacity that can be refilled through conversion to judicious land use(s) and adoption of recommended management practices of soil, vegetation and domesticated animals. Principal biomes for C sequestration, those with high capacity for C sequestration/emission avoidance and with numerous co-benefits, are peatlands and wetlands, degraded soils and desertified ecosystems, soils of agroecosystems and urban lands. Effective erosion control can also avoid emissions exacerbated by mineralization of C ­transported in runoff and eroded sediments and redistributed over the landscape. In addition to mitigating climate change, other co-benefits of C sequestration in the terrestrial biosphere are advancing food security, improving quality and quantity of water resources, and increasing the habitat and total biodiversity. Being an engine of economic development, improvements in productivity of agricultural, forestry and other managed ecosystems can advance the Millennium Development Goals, promote political and social stability, and improve standards of living. This is a win-win option in the context of climatic, environmental, political, economic and social issues facing the Carbon Civilization of the twenty-first century.