برآوردهای جهانی از مقادیر بازار و غیر بازاری حاصل شده از تصاویر شب های ماهواره ای، پوشش زمین، و ارزیابی خدمات اکوسیستم

We estimated global marketed and non-marketed economic value from two classified satellite images with global coverage at 1 km2 resolution. GDP (a measure of marketed economic output) is correlated with the amount of light energy (LE) emitted by that nation as measured by nighttime satellite images. LE emitted is more spatially explicit than whole country GDP, may (for some nations or regions) be a more accurate indicator of economic activity than GDP itself, can be directly observed, and can be easily updated on an annual basis. As far as we know, this is the first global map of estimated economic activity produced at this high spatial resolution (1 km2). Ecosystem services product (ESP) is an important type of non-marketed value. ESP at 1 km2 resolution was estimated using the IGBP land-cover dataset and unit ecosystem service values estimated by Costanza et al. [Valuing Ecosystem Services with Efficiency, Fairness and Sustainability as Goals. Nature's Services, Island Press, Washington DC, pp. 49–70]. The sum of these two (GDP+ESP)=SEP is a measure of the subtotal ecological–economic product (marketed plus a significant portion of the non-marketed). The ratio: (ESP/SEP)×100=%ESP is a measure of proportion of the SEP from ecosystem services. Both SEP and %ESP were calculated and mapped for each 1 km2 pixel on the earth's surface, and aggregated by country

Economic activity is fundamentally a spatial phenomenon. Both traditional marketed economic activities (like manufacturing, sales, and final consumption) and ‘non-marketed’ ecosystem services occur at specific spatial locations and are associated with specific natural, agricultural, or urban ecosystems. A necessary step toward better understanding these activities and services is to map their spatial patterns. That is what we have tried to do in this paper, at both the global and national level. Various measures of ‘economic activity’ and environmental quality are also important as ‘indicators’ for policy decisions. Key questions here revolve around exactly what the indicators measure. Gross Domestic Product (GDP) is the most popular indicator of economic performance. But GDP measures only marketed economic activity or gross income ( Costanza et al., 2001). It was never intended as a measure of economic welfare, and it functions very poorly as a welfare measure. Yet it is inappropriately used as a national welfare measure in far too many circumstances.

This paper presents a spatially explicit map (1 km2 resolution) of marketed economic activity derived from nighttime satellite imagery and nationally aggregate measures of GDP (Fig. 2), non-marketed economic activity derived from ecosystem service valuation and a global landcover dataset (ESP, Fig. 2), in addition to several nationally aggregated measures and other manipulations of these maps (Fig. 5, Fig. 6 and Fig. 7). One particular measure derived from these datasets was percent of economy derived from ecosystem services (%ESP, Fig. 8). %ESP correlated significantly with the Eco-Deficit indicator of Wackernagel, and did not correlate at all with the 2001 Environmental Sustainability Index (Fig. 9). The spatially explicit measures of market and non-market activity provide a mechanism for incorporating spatial context into ecosystem service valuation and enhancing the nature of dynamic models that attempt to characterize changes over time to the value of ecosystem services. Certainly, much remains to be done in assessing the ‘real’ wealth of nations and the relative contribution of ecosystem services to that wealth. We have provided only a first step in the direction of making that picture more spatially explicit and more comprehensive. But that step has shown that the path is likely to be a fruitful one.