Summary1. Political commitment and policy instruments to halt biodiversity loss require robust data and a diverse indicator set to monitor and report on biodiversity trends. Gaps in data availability and narrow-based indicator sets are significant information barriers to fulfilling these needs. 2. In this paper, the reporting requirements of seven global or European biodiversity policy instruments were reviewed using the list of Essential Biodiversity Variables (EBVs) as an analytical framework. The reporting requirements for the most comprehensive policy instrument, the United Nation's Strategic Plan for Biodiversity 2011-2020, were compared with the indicator set actually used for its reporting, to identify current information gaps. To explore the extent to which identified gaps could be bridged, the potential contribution of data mobilization, modelling and further processing of existing data was assessed. 3. The information gaps identified demonstrate that decision-makers are currently constrained by the lack of data and indicators on changes in the EBV classes Genetic Composition and, to a lesser extent, Species Populations for which data is most often available. Furthermore, the results show that even when there is a requirement for specific information for reporting, the indicators used may not be able to provide all the information, for example current Convention of Biological Diversity indicators provide relatively little information on changes in the Ecosystem Function and Ecosystem Structure classes. This gap could be partly

Biodiversity is continuing to decline. This crisis has been recognised by the Convention on Biological Diversity (CBD), whose members have set ambitious targets to avert ongoing declines in the state of biodiversity by 2020. These so called "Aichi Biodiversity Targets" (ABTs) are organized around five strategic goals, with indicators showing the level of progress made towards each target. Currently, measurements of many ABT indicators are not available. The Essential Biodiversity Variable (EBV) framework, developed by the Group on Earth Observations Biodiversity Observation Network (GEO BON), attempts to form a coherent and harmonised set of observations of biodiversity. In this paper, we explore the potential role of Earth Observation (EO) as a tool to support biodiversity monitoring against the ABT and EBV frameworks. We show that EO-based measurements are adequate for assessing progress towards 11 out of 20 ABTs. In addition, 14 of the 22 candidate EBVs have a fully or partly remotelysensed component and can be considered as Remote Sensing Essential Biodiversity Variables (RS-EBVs). Those with a partial EO component require further in-situ data and/or modelling effort to complete the EBV. While the status of biodiversity can be assessed with both fully and partly measured RS-EBVs, assessing trends is more challenging, particularly for partly measured RS-EBVs, as coincident time series of EO and supporting data are lacking. A synthetic pathway for developing generic biodiversity indicators using RS-EBVs is proposed.

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