Global mapping and estimation of ecosystem services values and gross domestic product: A spatially explicit integration of national ‘green GDP’ accounting
The economic value of ecosystem services (non-market) and the market value (represented by a proxy of gross domestic product (GDP)) represent the synthetic green GDP of the earth and of different nations. Mapping and estimating national green GDPs is a challenging task. In this study, we estimated the global market and non-market monetary values using two images, GlobCover 2009 and nighttime satellite imagery, as well as a comprehensive dataset. We also developed an integrated method supported by geographic information system (GIS) techniques, focused on spatial heterogeneity and real value, to create synthetic green GDP maps at global and national scales. Our results show that in 2009, for the entire biosphere, the ecosystem services value (ESV) could be estimated at US$ 149.61 trillion. Approximately 75.15% of the ESV is contributed by marine systems. The world GDP in 2009 was about US$ 71.75 trillion (for 225 countries or regions), resulting in a ratio of total ESV to GDP of approximately 2.09–1. Nighttime satellite imagery represents a more spatially explicit indicator of market value than does GDP. We also found that the distribution of the synthetic national green GDPs follows Zipf's Law, which holds that internal coherence exists among countries. A crude but simple indicator of the %ESV indicates that the relationship between the GDP and ESV is not always in a fixed pattern. The reliability of this result was demonstrated by comparing it with previous research and other relevant indices. We found a very high degree of confidence associated with this product. The method presented here is generally applicable at the global and continental scales and is applicable at the national scale for mapping the ESV and GDP. We hope that the results of this study will inform both policy-makers and the public about national green GDPs and encourage them to incorporate these values into policy decisions.