FAO Forestry Paper 177. Food and Agriculture Organization of the United Nations. Rome, 2016, 151 pp. (ISBN 978-92-5-109312-2).
Ahistoric achievement was realized in Paris in December 2015 when most of the world's greenhouse gas (GHG) emitting countries voluntarily submitted their post-2020 plans for action on climate change. These Intended Nationally Determined Contribution plans are aimed at keeping the global temperature rise well below 2°C, but apparently, the plans will require substantial improvement to attain that goal.1 Adjusting these plans is undoubtedly complex, but regardless of the specifics, it is difficult to imagine any mitigation or adaptation plan that does not include forests and other woody vegetation. By the process of photosynthesis, plants take in the GHG CO2 from the atmosphere, and use energy from the sun to power chemical reactions with water to form sugar, a building block of life. Woody plants can accrue huge amounts of carbon from the atmosphere, and these stocks persist: Globally, forests store 861 (±66) petagrams of carbon.2 This process of carbon removal and deposition into long-lived storages such as forests is defined as carbon sequestration by the United Nations Framework Convention on Climate Change.3 Natural processes such as plant respiration and organic matter decomposition, as well as both natural and human-caused disturbances, emit CO2 back into the atmosphere. As such, many factors interact to determine whether a forest will function as a sink that reduces atmospheric CO2 levels and mitigates global warming, or as a source of CO2. Rapidly growing and well-managed forests capture more CO2 from the atmosphere than they emit and can accumulate large stocks of carbon in the vegetation and soil.4 On the other hand, deforestation represents a loss in the capacity to absorb CO2 from the atmosphere and also results in emissions of CO2. Land-use change and forestry accounted for 10–12% of global GHG emissions during 2000–2011. However, forests, as a result of their growth, were a net sink for CO2 over the 2000–2009 period by a variety of estimation methods.5
Ann E. Russell is an adjunct associate professor in the Department of Natural Resource Ecology and Management at Iowa State University, Ames, Iowa.
B. Mohan Kumar is a professor and Dean (acting), School of Ecology and Environment Studies, Nalanda University, Rajgir, District Nalanda, Bihar, India.