The biodiversity and high productivity of coastal terrestrial and aquatic habitats are the foundation for important benefits to human societies around the world. These globally distributed habitats need frequent and broad systematic assessments, but field surveys only cover a small fraction of these areas. Satellite-based sensors can repeatedly record the visible and near-infrared reflectance spectra that contain the absorption, scattering, and fluorescence signatures of functional phytoplankton groups, colored dissolved matter, and particulate matter near the surface ocean, and of biologically structured habitats (floating and emergent vegetation, benthic habitats like coral, seagrass, and algae). These measures can be incorporated into Essential Biodiversity Variables (EBVs), including the distribution, abundance, and traits of groups of species populations, and used to evaluate habitat fragmentation. However, current and planned satellites are not designed to observe the EBVs that change rapidly with extreme tides, salinity, temperatures, storms, pollution, or physical habitat destruction over scales relevant to human activity. Making these observations requires a new generation of satellite sensors able to sample with these combined characteristics: (1) spatial resolution on the order of 30 to 100-m pixels or smaller; (2) spectral resolution on the order of 5 nm in the visible and 10 nm in the short-wave infrared spectrum (or at least two or more bands at 1,030, 1,240, 1,630, 2,125, and/or 2,260 nm) for atmospheric correction and aquatic and vegetation assessments; (3) radiometric quality with signal to noise ratios (SNR) above 800 (relative to signal levels typical of the open ocean), 14-bit digitization, absolute radiometric calibration <2%, relative calibration of 0.2%, polarization sensitivity <1%, high radiometric stability and linearity, and operations designed to minimize sunglint; and (4) temporal resolution of hours to days. We refer to these combined specifications as H4 imaging. Enabling H4 imaging is vital for the conservation and management of global biodiversity and ecosystem services, including food provisioning and water security. An agile satellite in a 3-d repeat low-Earth orbit could sample 30-km swath images of several hundred coastal habitats daily. Nine H4 satellites would provide weekly coverage of global coastal zones. Such satellite constellations are now feasible and are used in various applications.

Many conservation professionals are familiar with the Convention on International Trade in Endangered Species (CITES), the Convention on Migratory Species (CMS), the Convention on Biological Diversity (CBD), the Ramsar Convention, and the World Heritage Convention. Regional instruments, such as those focusing on Africa, Antarctica, or Europe, are also conspicuous features of the conservation arena. Other international wildlife agreements focus on particular species, such as polar bears or albatrosses, or particular transboundary protected areas, such as the huge Kavango-Zambezi Transfrontier Conservation Area (see table 1). These agreements are collectively known as international wildlife law (Bowman et al. 2010). The binding agreements themselves are typically accompanied and informed by an evolving set of nonbinding instruments, such as Conference of the Parties (COP) decisions and action plans.

The Ramsar Convention recognizes the interdependence of people on wetlands for their important economic, cultural, scientific and recreational values. The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) provides a framework for considering the multiple values of nature, including wetlands, and its benefits to society within policy-making and decisionmaking processes. The recognition of the diverse values of wetlands is essential to their wise use, and to ensuring that their role is reflected in global policy processes such as the 2030 Agenda for Sustainable Development, the Sendai Framework for Disaster Risk Reduction and the Paris Agreement on climate change.
This Policy Brief can support policy-makers by informing and facilitating the integration of the multiple values of wetlands across sectors, supported by improved valuation studies, to enhance the relevance and impact of policies.