Deforestation: Drivers, Implications, and Policy Responses
- Christiane W. RunyanChristiane W. RunyanDepartment of Environmental Sciences, Johns Hopkins University
- and Jeff StehmJeff StehmJohns Hopkins University
Over the last 8,000 years, cumulative forest loss amounted to approximately 2.2 billion hectares, reducing forest cover from about 47% of Earth’s land surface to roughly 30% in 2015. These losses mostly occurred in tropical forests (58%), followed by boreal (27%) and temperate forests (8%). The rate of loss has slowed from 7.3 Mha/year between 1990–2000 to 3.3 Mha/year between 2010–2015. Globally since the 1980s, the net loss in the tropics has been outweighed by a net gain in the subtropical, temperate, and boreal climate zones. Deforestation is driven by a number of complex direct and indirect factors. Agricultural expansion (both commercial and subsistence) is the primary driver, followed by mining, infrastructure extension, and urban expansion. In turn, population and economic growth drive the demand for agricultural, mining, and timber products as well as supporting infrastructure. Population growth and changing consumer preferences, for instance, will increase global food demand 50% by 2050, possibly requiring a net increase of approximately 70 million ha of arable land under cultivation. This increase is unlikely to be offset entirely by agricultural intensification due to limits on yield increases and land quality. Deforestation is also affected by other factors such as land tenure uncertainties, poor governance, low capacity of public forestry agencies, and inadequate planning and monitoring. Forest loss has a number of environmental, economic, and social implications. Forests provide an expansive range of environmental benefits across local, regional, and global scales, including: hydrological benefits (e.g., regulating water supply and river discharge), climate benefits (e.g., precipitation recycling, regulating local and global temperature, and carbon sequestration), biogeochemical benefits (e.g., enhancing nutrient availability and reducing nutrient losses), biodiversity benefits, and the support of ecosystem stability and resiliency. The long-term loss of forest resources also negatively affects societies and economies. The forest sector in 2011 contributed roughly 0.9% of global GDP or USD 600 billion. About 850 million people globally live in forest ecosystems, with an estimated 350 million people entirely dependent on forest ecosystems for their livelihoods. Understanding how to best manage remaining forest resources in order to preserve their unique qualities will be a challenge that requires an integrated set of policy responses. Developing and implementing effective policies will require a better understanding of the socio-ecological dynamics of forests, a more accurate and timely ability to measure and monitor forest resources, sound methodologies to assess the effectiveness of policies, and more efficacious methodologies for valuing trade-offs between competing objectives.
- Pollution and Threats to the Environment (Social Science)
- Management of Land and Natural Resources (Social Science)