For environmental sustainability, decision-makers require consistent, accurate and detailed information to advise and support the necessary actions. But in many parts of the world, access to such data is often costly or non-existent. Co$ting Nature is a web-based tool that has over 80 datasets already inputted allowing users to make quick but robust conservation focused decisions.
Co$ting Nature, developed by Dr Mark Mulligan (King’s College London) in collaboration with AmbioTEK and UNEP-WCMC, assesses ecosystem services (ES)—the benefits people obtain from nature  — provided anywhere in the world, identifying their beneficiaries and assessing the impacts of human interventions and scenarios (Box 1). Co$ting Nature provides policy support for the sustainable management of ES through the definition of conservation priority, based on the spatial distribution of ES, critical ecosystems and current human pressures as well as future threats .
Currently, nearly a third of the species assessed by the IUCN Red List are threatened with extinction . Around 60% of the ES evaluated by the Millennium Ecosystem Assessment had been degraded or used unsustainably a decade ago. The recently developed Red List of Ecosystems estimates that 27 of the 32 assessed ecosystem are threatened with collapse. Clearly, we need to find a balance between human well-being and maintenance of natural environments.
This difficult task involves multi-level decision-making — from international laws to individual lifestyle— that relies on scientific evidence. However, decision-makers face major challenges when it comes to obtaining and applying the evidence. Some of these challenges are lack, inaccessibility and uncertainty of data. Even when data is available and accurate, if highly specialized knowledge is required to interpret it, or it cannot be applied under the expected scenarios for change, it becomes difficult to use .
How does Co$ting Nature support decision-making?
Co$ting Nature overcomes these challenges by bringing data and knowledge together, in a user-friendly system, for conservation and development governmental and non- governmental organizations, policy analysts, agriculture and industry, education and academic researchers. Here, spatial datasets from remote sensing (e.g. forest loss and gain, carbon stock) and other global sources (e.g. biodiversity hotspots, urban areas) are provided to model several biophysical and socioeconomic processes, to calculate a baseline for ecosystem services anywhere globally. Users can include their own datasets if desired. Also, it allows a series of interventions or scenarios of change to assess their impact on ES provision (see Box 2).
Conservation priority, biodiversity, water quantity and quality, water provisioning services, carbon services, nature-based tourism, threats and pressures, vulnerability to hazards and beneficiaries are the modules  calculated to produce a series of summary maps indexed (from 0 to 1) globally (Fig. 1) . These maps include:
- Relative conservation priority index – conservation priority of the major conservation NGOs
- Relative biodiversity priority index – combines relative richness and relative endemism for red list (threatened) species for the groups mammals, amphibians, reptiles and birds.
- Relative aggregate nature conservation priority index (potential services) – this combines total potential services (all services) and total nature conservation priority (which combines the relative conservation priority index with the biodiversity priority, current pressure [Fig. 1A], and future threat indices [Fig.1B]). Potential services are provided but not necessarily consumed, but they are available for in the future.
- Relative aggregate nature conservation priority index (realised services) – this combines total realised services (Fig. 1C) and total nature conservation priority. Unlike potential services, here the calculations depend on demand for services as well as supply (Fig. 1D).
The output maps, statistics and model narratives are extremely useful instruments for decision-makers and institutions for several reasons . These allow them:
- To spatially identify which areas should be maintained due to their current high supply of ES
- To guide new strategies that will ensure the future supply of ES — potential ES
- To assess spatial trade-offs among ES
- To identify synergies among multiple ES
- To prioritize areas whose conservation will achieve multiple conservation goals
Co$ting Nature does not value nature in monetary terms users can employ Co$ting Nature outputs to apply their own valuing criteria.
Costing nature users and applications
Currently, Co$ting Nature — along with the other Policy Support Systems by the same developers— is used by 1200 users of over 1000 organizations in 141 countries around the world  (Fig. 2). The main applications of this tool include baseline ES assessment, general analysis of pressures and threats on services or biodiversity, specific planned agricultural, industrial or extractive interventions and co-benefits analysis.
An example of co-benefit analysis was presented by Kelly Gunnell (King’s College London) in the symposium Space – the final frontier for biodiversity monitoring?, hosted by the Zoological Society of London (29 April 2016). Here, Gunnell and Mulligan used Co$ting Nature to asses the potential ‘co-benefits’ for biodiversity of areas of natural green infrastructure in five global cities. Initial results show high spatial correlation between biodiversity and green storage, but further research is required . The relationship between natural infrastructure and species richness is one among many questions that can be answered using this tool. Co$ting Nature developers provide several examples of applications.
 Millennium Ecosystem Assessment (2005) Ecosystems and Human Well-being: Synthesis. Island Press, Washington DC
Mulligan M (2016) User guide for the Co$ting Nature Policy Support System Version 2. Available online https://goo.gl/Grpbnb
 Mulligan M, Guerry A, Arkema K, Bagstad K, Villa F (2010) Capturing and quantifying the flow of ecosystem services in Silvestri S, Kershaw F (eds.) Framing the flow: Innovative Approaches to Understand, Protect and Value Ecosystem Services Across Linked Habitats. UNEP World Conservation Monitoring Centre, Cambridge, UK. ISBN 978-92-807-3065-4. [available here]
 Mulligan, M. (2015) Trading off agriculture with nature’s other benefits, spatially in Zolin, C.A and Rodrigues, R de A.R. (eds) Impact of Climate Change on Water Resources in Agriculture. CRC Press ISBN 9781498706148
 IUCN (2015) Conservation successes overshadowed by more species declines – IUCN Red List update. Available online IUCN International News
 IUCN (2016) Assessments. IUCN Red List of Ecosystems. Available on line http://iucnrle.org/assessments/
 Mulligan (2016) ‘Co$ting Nature comparisons with ForestPlots.net data as a demonstrator for ASTROTROP’ Unpublished presentation at ASTROTROP Conference 2, 23-24 February, School of Geography, University of Leeds, Leeds
 Mulligan M (2016) Co$ting Nature Version 2 Modules, Model documentation. Available online goo.gl/xQA4pP
 Martínez-Harms MJ, Balvanera P (2012) ‘Methods for mapping ecosystem service supply: a review’ International Journal of Biodiversity Science, Ecosystem Services & Management 8: 17-25. doi:10.1080/21513732.2012.663792
 Gunnell K, Mulligan M (2016) Biodiversity co-benefits of natural ‘green’ water storage infrastructure upstream of global cities. Unpublished presentation at: Space – the final frontier for biodiversity monitoring? Symposium, 29 April 2016, ZSL Meeting Rooms, London