Choose Satellites to Monitor Deforestation Illegal Logging Threatens Tropical Forests and Carbon Stocks

COMMENT EVOLUTION We must not forget CAREERS E. O. Wilson’s EXHIBITION Show of PUBLISHING What sorts of the lessons of Willi Hennig, pragmatic, passionate advice rare treatises charts science books are selling father of cladistics p.295 to young scientists p.297 history of anaesthesia p.298 well? p.299 UK-DMC2/DMC INTERNATIONAL IMAGING INTERNATIONAL UK-DMC2/DMC

An image from the UK-DMC2 satellite shows forest in the Brazilian Amazon in red and cleared areas in green (detail in inset). Choose satellites to monitor deforestation Illegal logging threatens tropical forests and carbon stocks. Governments must work together to build an early warning system, say Jim Lynch and colleagues.

ropical deforestation contributes enhancement of forest carbon stocks. The proposed so far are too sparse and slow, mak- 12% of total anthropogenic carbon Intergovernmental Panel on Climate Change ing it impossible to identify forest damage dioxide emissions globally1. Illegal (IPCC) is also developing forest remote- until at least a year later. Tlogging is costing nations tens of billions of sensing plans for consideration by the We believe that an early warning system dollars each year. Although governments are 19th Conference of the Parties (COP-19) to is needed to allow authorities to stop illegal making headway on agreements to stop this the United Nations Framework Convention logging quickly. Two strategies are necessary destruction, so far there is no coherent plan on Climate Change (UNFCCC), which will to achieve this: first, a new set of tropical to monitor tropical forests on the scale or be held in Warsaw this November. orbiting radar satellites that can ‘see’ through timescales necessary to do so. Satellites provide the only means of viewing clouds to monitor global forests daily; sec- Incentives are being negotiated for vast forest areas regularly — the tropics cover ond, a plan for existing satellites to assess states to implement the United Nations almost half of Earth’s land area. But basic deci- forest carbon stocks several times a year, to REDD+ framework: Reducing Emissions sions have yet to be made on which Earth- account for seasonal variations. from Deforestation and Forest Degrada- observing systems should be used and how The REDD+ working group, which tion, extended to include conservation, forest data should be monitored, reported and meets in Bonn, Germany, from 29 April to sustainable management of forests and the verified. In our view, the mapping strategies 3 May, must agree on a comprehensive,

rapid-response global monitoring system between £250 million (US$384 million) and in time for it to be ratified at COP-19. £500 million each in orbit. Fortuitously, a new generation of lower-cost radar mini- REAL-TIME MONITORING satellites is due to be launched within More than one billion people depend on the next year. These include the British forests for their livelihood. The illegal log- NovaSAR-S range (£45 million launched and

ging trade is estimated to be worth between insured). The European Sentinel-1 mission SIGIT PAMUNGKAS/REUTERS US$30 billion and $100 billion annually, with and the Japanese ALOS-2 satellite each cost governments losing $10 billion each year in about ten times this. tax income2. Stolen wood is estimated to Radar and optical systems are both depress world timber prices by up to 16%. needed. An early warning constellation of As well as curbing these losses, imple- five tropical-orbiting radar satellites should menting REDD+ and halving deforestation provide daily scanning of tropical forests rates by 2050 would prevent the release of at 5–20-metre resolution, irrespective of 50 petagrams of carbon in total into the weather, to monitor logging in real time. atmosphere3,4, saving a potential warming We estimate that this could be done for of 0.14 °C. This is a small but crucial step £200 million, plus a dedicated ground crew. towards potentially much larger carbon Ideally, these data should be managed by an savings. international consortium that includes devel- Implementing REDD+ will require many oped and developing countries, and would facets of the carbon cycle to be monitored, Illegal logging in Indonesia costs billions. be run under the auspices of the UNFCCC. including tree cover and carbon emissions Low-resolution optical satellites can be from felling. There is also a need to assess image survey a year — insufficient to track constructed cheaply to monitor forests weekly the state and health of forests by analysing seasonal variations in forest carbon stocks. or monthly throughout the year7. Existing colour changes due to chlorophyll loss. Bio- To achieve good annual coverage, optical satellite systems, including NASA’s MODIS, mass, dead organic matter and soils must be measurements should be taken at least every DMC, SPOT or Landsat, could contribute, included in the carbon budget. 1–2 weeks. To spot illegal logging, coverage with much of the data made available for free. Because different types of forest vary in needs to be even more frequent. Observa- But to provide regular ground data with their capacity to store carbon, changes in tions must be made at least daily, with data which to calibrate all these satellite observa- land use must be recognized. For example, analysed much more quickly than at the tions and reduce uncertainties in their carbon Indonesia’s policy of converting its 91 mil- current rate of months. If we are to protect estimates, major efforts will also be required lion hectares of tropical forest to oil palm tropical forests, we must go beyond map- by those countries participating in REDD+. plantations reduces the land’s value from ping damage long after it has happened and As discussions continue this year, we urge a REDD+ perspective, because much less instead offer early warnings. policy-makers to back the right satellites and carbon is being stored. Around 72% of the strategies to monitor and save the world’s frontier forest has already been lost. WAY FORWARD forests. ■ Optical and radar satellites working in dif- Governments and the IPCC need to accept ferent parts of the electromagnetic spectrum that satellites are the only efficient and realis- Jim Lynch is professor at the Centre for can monitor all of these characteristics. But tic way to provide monitoring for REDD+5,6. Environmental Strategy, University of international bodies and governments have This must be enshrined in international law Surrey, Guildford, UK. Mark Maslin is been slow to formulate and agree on common through the UNFCCC process and docu- professor in the Department of Geography, guidelines for so doing. Without the right mented in detail. Governments must com- University College London, UK. Heiko technologies or globally accepted assessment mit to securing and maintaining systems of Balzter is director of the Centre for standards, billions of dollars could be wasted Earth-observing satellites to perform the Landscape and Climate Research, University on projects that do not deliver. monitoring. of Leicester, UK. Martin Sweeting is The European Union has focused on Remote-sensing satellites operate in two director of the Surrey Space Centre, preventing illegal logging, rather than spectral regimes: optical and radar. Optical University of Surrey, Guildford, UK. specifying how forestry information should sensors in different colours are sensitive to e-mail: [email protected] be collected by countries signed up to its vegetation greenness, fractional tree cover, 2005 Forest Law Enforcement, Govern- forest type and vegetation density. They 1. Friedlingstein, P. et al. Nature Geosci. 3, 811–812 (2010). ance and Trade regulation. This has led to can cover millions of square kilometres 2. Nellemann, C., INTERPOL Environmental Crime a proliferation of incomparable collection in a single image while resolving detail to Programme (eds). Green Carbon, Black Trade methods. Moreover, there is no plan for 20 metres, or down to 1 metre over a smaller (United Nations Environment Programme, GRIDArendal; 2012). REDD+ carbon credits to be accepted in the area. Current Earth-observation efforts 3. Gullison, R. E. et al. Science 316, 985–986 European Union Emissions Trading Scheme. include NASA’s Terra and Aqua satellites, the (2007). Some groups have published guidelines China–Brazil Earth Resources Satellite pro- 4. Canadell, J. G. & Raupach, M. R. Science 320, 1456–1457 (2008). for satellite monitoring for REDD+, includ- gramme, the Disaster Monitoring Constel- 5. Global Observation of Forest and Land Cover ing the UN Food and Agriculture Organiza- lation (DMC) and France’s SPOT satellite. Dynamics. Reducing Greenhouse Gas Emissions tion’s Global Observation of Forest and Land Radar systems, unlike optical systems, from Deforestation and Degradation in Developing Countries (GOFC-GOLD, 2012); available at Cover Dynamics programme and the Group can penetrate cloud cover, which is com- go.nature.com/fk3ixp. on Earth Observations’ Global Forest Obser- mon in the tropics. The microwave signals 6. Herold, M. et al. Carbon Balance Mgmt 6, 13 vations Initiative. In our view, these reports transmitted by Synthetic Aperture Radar (2011). lack ambition and an understanding of the (SAR) satellites, such as TerraSAR-X, are 7. Maslin, M. & Scott, J. Nature 475, 445–447 (2011). potential of satellites. Another group, the reflected back by leaves, branches and Committee on Earth Observation Satellites, trunks to the satellite’s receivers. Such satel- The authors declare competing financial interests: for example, foresees doing only one optical lites have historically been expensive, costing for details see go.nature.com/x6dtxy.