Satellite Earth observations (EO) are unique in their ability to provide consistent and comparable information on global land cover. Imagery may be used to measure the extent of land cover types and their change over time. This is complemented by radar imagers that can provide further information on vegetation type, soil moisture and biomass and can measure day-and-night, in all weather conditions, and ‘through’ some forest canopies.
Satellite EO is a fundamental tool for deriving statistics on deforestation and land use change and is critical to monitoring the Indicators of SDG Targets 15.2, 15.3 and 15.b from local to national, regional and even global scales – in some cases allowing the assessment of trends over long historical archives.
Land degradation
Land degradation is a process of change over time in vegetation cover, water resources, soil erosion and salinity. Time series of coarse to moderate resolution EO data can be applied globally to reveal environmental changes and target hot spots, and is used by national, state, and municipal governments to manage their land use. Standardised methods are being developed to allow consistent derivation of three sub-Indicators for Indicator 15.3.1:
- land cover and land cover change (see ESA Landcover CCI);
- land productivity; and,
- carbon stocks above and below ground.
The UN Convention to Combat Desertification (UNCCD) commissioned a series of Good Practice Guidance reports to help countries select, process and analyse datasets to report against these sub-Indicators, with EO closely integrated into the recommended methods.
Forests
At the global level, FAO has been carrying out its Forest Resources Assessments (FRA) at 5–10 year intervals since 1946. From 1990, information collected through country reporting has been complemented by remotely-sensed data, supported by a growing archive of satellite imagery and new software for image processing and interpretation.
The World Resources Institute’s Global Forest Watch (GFW) uses wall-to-wall national coverage satellite EO data (Landsat) to provide spatially explicit information at the pixel level (30m). Information is presented via an online forest monitoring and alert system empowering forest management stakeholders to create custom maps, analyse forest trends, subscribe to alerts or download data for their local area or the entire world.
The REDD+ initiative of the UN Framework Convention on Climate Change (UNFCCC) looks to provide financial incentives for countries to maintain and sustain forests in an effort to reduce emissions from deforestation and forest degradation, foster conservation and management of forests, and enhance forest carbon stocks.
In support of REDD+, the Global Forest Observations Initiative (GFOI) aims to guarantee availability of wall-to-wall national coverages of satellite data and to provide countries with Methods and Guidance Documentation (MGD) that will facilitate reporting consistent with the relevant IPCC Good Practice Guidelines. GFOI’s MGD advice is available in English, Spanish and French (www.gfoi.org/methods-guidance/) and via a new online tool – REDDCompass – that guides users through the core themes, concepts and actions involved in the development of National Forest Monitoring Systems.
