Estimating tropical deforestation from Earth observation data Frédéric Achard, Hans-Jürgen Stibig, Hugh D Eva, Erik J Lindquist, Alexandre Bouvet, Olivier Arino, Philippe Mayaux To cite this version: Frédéric Achard, Hans-Jürgen Stibig, Hugh D Eva, Erik J Lindquist, Alexandre Bouvet, et al.. Esti- mating tropical deforestation from Earth observation data. Carbon Management, 2010, 1 (2), pp.271- 287. 10.4155/CMT.10.30. hal-00565052 HAL Id: hal-00565052 https://hal.archives-ouvertes.fr/hal-00565052 Submitted on 10 Feb 2011 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. For reprint orders, please contact [email protected] Review Estimating tropical deforestation from Earth observation data Carbon Management (2010) 1(2), 271–287 Frédéric Achard†1, Hans-Jürgen Stibig1, Hugh D Eva1, Erik J Lindquist2, Alexandre Bouvet1, Olivier Arino3 & Philippe Mayaux1 This article covers the very recent developments undertaken for estimating tropical deforestation from Earth observation data. For the United Nations Framework Convention on Climate Change process it is important to tackle the technical issues surrounding the ability to produce accurate and consistent estimates of GHG emissions from deforestation in developing countries. Remotely-sensed data are crucial to such efforts. Recent developments in regional to global monitoring of tropical forests from Earth observation can contribute to reducing the uncertainties in estimates of carbon emissions from deforestation. Data sources at approximately 30 m × 30 m spatial resolution already exist to determine reference historical rates of change from the early 1990s. Key requirements for implementing future monitoring programs, both at regional and pan-tropical regional scales, include international commitment of resources to ensure regular (at least yearly) pan-tropical coverage by satellite remote sensing imagery at a sufficient level of detail; access to such data at low-cost; and consensus protocols for satellite imagery ana lysis. Role of tropical deforestation in global large loss of carbon stock per unit area relative to other carbon emissions practices in forests (e.g., logging) that may only result Tropical deforestation is estimated to total approxi- in forest degradation and lower loss of carbon stock [7]. mately 13 million ha per year in the period 2000–2010 Deforestation in the tropics is thought to be a major compared with 16 million ha per year in the period contributor to GHG emissions. Emissions from tropical 1990–2000 [1]. The net loss of forest area globally has deforestation, forest and peat degradation are currently been significantly reduced from -8.3 million ha per year estimated to be 15% of the world’s anthropogenic GHG between 1990 and 2000 to -5.2 million ha between emissions, mainly through CO2 emissions (in the range 2000 and 2010. This reduction of net loss is largely due of 8–20%) [8]. For the period 1997–2006, global net to an increase in afforestation, natural forest regrowth, carbon emissions resulting from land-use changes, pre- reforestation and forest plantations. However, the global dominantly deforestation in the tropics and peat degra- rate of gross deforestation, mainly the conversion of dation, have been estimated at 1.5 GtC yr–1 (in the range tropical forests to agricultural land, is still alarmingly of 1.1–1.9 GtC yr–1); 1.22 GtC yr–1 from deforestation high and has significant impacts on global climatic and forest degradation and 0.3 GtC yr–1 from peat deg- change and biodiversity issues. radation, when the total global anthropogenic emissions Tropical deforestation, resulting from different (i.e., fossil fuel and cement emissions + flux resulting –1 causes [2–4], leads to emissions of CO2 and, if the bio- from land use changes) were 10.1 GtC yr in 2008. mass is burned during the clearing process, additional Old-growth tropical forests store carbon at an –1 –1 non-CO2 gases are emitted [5,6]. Deforestation causes a estimated rate of 0.5 tC ha yr (confidence interval 1Institute for Environment & Sustainability, Joint Research Centre of the European Commission, 21020 Ispra (VA), Italy 2Forest Assessment, Management & Conservation Division, United Nations Food & Agriculture Organization, Viale delle Terme di Caracalla, Rome 00153, Italy 3European Space Agency, ESRIN, Via Galilleo Galilei, 00044 Frascati, Italy †Author for correspondence: Tel.: +39 033 278 5545; E-mail: [email protected] future science group 10.4155/CMT.10.30 © European Union, 2010 ISSN 1758-3004 271 Review Achard, Stibig, Eva et al. Key terms [CI]: 0.29–0.66) [9], which leads carbon stocks and satellite-derived maps of changes in –1 Forest: As adopted by the United to a carbon sink of -1.3 GtC yr forest cover to the estimation of emissions [14]. Data Nations Framework Convention on (CI: 0.8–1.6) across all tropical on forest carbon stocks at both continental and global Climate Change at the 7th Conference forests during recent decades. Such scales is improving [20–22]. It has been suggested that of the Parties (COP-7) under the estimates are consistent with a study lack of funding limits efforts to reduce uncertainties of ‘Marrakesh accords’, “For land use, land-use change and forestry activities combining ana lysis of atmospheric estimates of biomass [23]. under Article 3, paragraphs 3 and 4 of CO2 concentration data and atmo- the Kyoto Protocol, the following spheric transport models, which Reducing emissions from tropical deforestation: definitions shall apply: (a) “Forest” is a report a net tropical emission of a recent mechanism of the United Nations minimum area of land of 0.05–1.0 ha –1 with tree crown cover (or equivalent +0.1 GtC yr [10], which then can Framework Convention on Climate Change stocking level) of more than be related as the sum of emissions Although uncertainties in emissions from tropical defor- 10–30 percent with trees with the from land-use changes, predomi- estation are high, the contribution of such emissions to potential to reach a minimum height of –1 2–5 m at maturity in situ. A forest may nantly in the tropics (+1.5 GtC yr ) the global carbon budget is recognized by the inter- consist either of closed forest and uptake from remaining tropical national climate change community as being very sig- formations where trees of various forests (-1.3 GtC yr–1). In comple- nificant. As a consequence, official international discus- stories, and undergrowth cover a high ment to carbon emissions, tropi- sions were initiated at the United Nations Framework proportion of the ground or open forest […].” COP-7 further noted that parties cal deforestation also weakens this Convention on Climate Change (UNFCCC) 11th recognize that there should be certain natural sink capacity. Conference of Parties (COP) on the issue of reducing flexibility. To date, most countries are However, uncertainties in the emissions from deforestation and degradation (REDD) defining forests with a minimum crown land-use change flux of the global in developing countries. At COP-11, the UNFCCC cover of 30%. carbon budget are high. As reported launched a process for investigating the technical issues Deforestation: As further adopted by in the Intergovernmental Panel surrounding the feasibility of reducing such emissions. the United Nations Framework Convention on Climate Change at on Climate Change (IPCC) 4th At the UNFCCC COP-15 held in Copenhagen in COP-7, “Deforestation is the direct Assessment report [11]: “The land use December 2009, the need to provide incentives for human-induced conversion of forested carbon source has the largest uncer- REDD was, for the first time, mentioned in the final land to nonforested land”. tainties in the global carbon bud- declaration of the Heads of State and governments, Earth observation: The gathering of get.” To obtain accurate estimates referred as Decision 2 of the COP-15 (2/CP.15). This information about planet Earth’s physical, chemical and biological of emissions from land-use changes decision follows on from Decision 2 of the COP-13 (2/ systems. It is used to monitor and assess in the tropics, several components CP.13) on “approaches to stimulate action” for “reduc- the status of, and changes in, the must be estimated accurately, in par- ing emissions from deforestation in developing coun- natural environment and the built ticular: area of forest cover changes; tries”. The Copenhagen Accord recognizes “the crucial environment. In recent years, Earth observation has become initial carbon stocks (above- and role of reducing emission from deforestation and forest technologically more and more below-ground biomass and soil degradation and the need to enhance removals of GHG sophisticated. It has also become more organic matter) in forests before emission by forests” and encourages the “immediate important owing to the significant deforestation or forest degradation; establishment of a mechanism including REDD-plus impact that modern human civilization is having on the Earth. and processes of changes in the car- to enable the mobilization of financial