An Empirical Environmental Sustainability Index derived solely from Nighttime Satellite Imagery and Ecosystem Service Valuation Paul Sutton Department of Geography University of Denver

Outline “What is an Environmental Sustainability Index?” Data and Methods used to prepare this index Results: Maps of Environmental Sustainability? Other ESIs: Wackernagel’s Eco-Deficit & 2001 ESI How do these ESIs intercompare? Future Research directions

Sustainable Development & Environmental Sustainability The 1987 Brundtland Report made the idea of Sustainability famous with the term ‘Sustainable Development’: “ Development that meets the needs of the present generation without compromising the ability of the future generations to meet their own needs.” Measuring Environmental Sustainability is a piece of this puzzle. Defining and/or measuring Environmental Sustainability is subject to great debate. Some methods have been suggested by the likes of Wackernagel, Ehrlich, and others.

Holdren & Ehrlich’s I=P*A*T conception of environmental sustainability Human ‘Impact’ must be balanced by the Environment’s ability to absorb said impact Daily & Ehrlich suggest that ‘Impact’ should not exceed either ‘Maximum Sustainable Use’ (MSU) or ‘Maximum Sustainable Abuse’ (MSA) Absolute measures of ‘sustainability’ are virtually impossible to make; however, RELATIVE measures might be reasonably made in order to compare the environmental sustainability of nations or regions of the world

Measuring Human ‘Impact’ What data can be used in the I = P*A*T formulation? If you use Population for P, GDP/Capita for Affluence, and CO 2 Emissions/GDP for Technology, then ‘Impact’ simplifies to total CO 2 emissions Daily & Ehrlich used Energy Consumption per Capita to capture the A*T “Impact” is a function of both population size and individual consumption levels Nighttime Imagery from the DMSP OLS correlates with Population, Energy Consumption, CO 2 emissions, and GDP and may be the best spatially explicit, single variable, measure of ‘Impact’

Measuring Maximum Sustainable Use and Maximum Sustainable Abuse The myriad ways in which human’s can impact the environment and the various ways the environment either supports or absorbs such actions are beyond the scope of this index. The proxy measure of MSA and MSU chosen was simply the value of the land’s ecosystem services as outlined by Costanza et. al. and calculated using a USGS global land cover data set at 1 km 2 resolution

Deriving The Eco-Value / Night Light Energy Environmental Sustainability Index This index is similar to the inverse of population density e.g. ‘square kilometers of land per person’ However; ‘square kilometers of land’ is adjusted by the land’s ecosystem service value; and, ‘per person’ is measured by the nighttime satellite imagery provided by the DMSP OLS

A representation of the datasets used to calculate Eco-Value and Impact from around Central America

Sustainability Scores According to the Eco-Value / Night Light Energy Index

Other National Measures of Environmental Sustainability The 2001 Environmental Sustainability Index produced by the Global Leaders of Tomorrow Environment Task Force of the World Economic Forum, The Yale Center for Environmental Law and Policy (YCELP), and the Center for International Earth Science Information Network (CIESIN) The ‘Eco-Deficit’ derived by Wackernagel and Rees which results from their ‘Ecological Footprint’ analysis and is in essence the difference between ‘Available Ecological Capacity’ and the ‘Ecological Footprint’ of nations.

Ecological Footprint Analysis “Ecological Footprint analysis is an accounting tool that enables us to estimate the resource consumption and waste assimilation requirements of a defined human population or economy in terms of corresponding productive land area.” The ‘Ecological Footprint’ ESI is also a composite index involving many variables. However, in contrast to the 2001 ESI these variables focus on the nature and productivity of land resources, variability of human consumption patterns, and the energy accounting of each nation’s international trade.

The 2001 Environmental Sustainability Index The 2001 ESI attempts to develop a ‘transparent, interactive process that draws on rigorous statistical, environmental, and analytic expertise to quantify environmental sustainability’. Key Results are: 1) Environmental Sustainability can be measured, 2) The Index creates benchmarks of environmental conditions that can influence decision making, 3) Serious ‘data gaps’ for many nations of the world should be filled, 4) Economic conditions affect, but do not determine, environmental conditions; and, policy regarding these conditions are separate choices. Calculated for 122 nations using 5 ‘Core’ indicators each of which were derived from 67 other variables. Correlates Strongly with GDP per Capita

Comparing the 2001 ESI to the Eco-Deficit The Correlation between the 2001 ESI and the Eco- Deficit of Wackernagel is not significant (R 2 = 0.03) The 2001 ESI incorporates more cultural and Institutional elements of sustainability along the lines of those described by Courtland Smith in a critique of the I=P*A*T formulation. And is consequently more of a ‘quality of life’ index than a sustainability index. The Eco-Deficit takes into account the separation of production and consumption in ways not accounted for in the 2001 ESI and may be a better of the global sustainability of a local people, nation, etc.

Scatterplots with Regressions of the three ESIs discussed here

Problems & Future Research General Definitions: lack of correlation between 2001 ESI and Eco-Deficit Index suggests that basic work on defining environmental sustainability still needs to be done. ESIs may be interesting but are they of any use? Specific to Eco-Value / Night Light Energy Index Scale problems with measuring Eco-Value Spatial Context problems with measuring Eco- Value e.g. Flood control around resevoirs

Conclusions Eco-Value / Night Light Energy Index correlates strongly with Eco-Deficit but not at all with 2001 ESI Consilience as to what is meant by the term ‘Environmental Sustainability’ remains elusive The ‘Eco-Value’ / Night Light Energy Index is simple, relatively objective, measureable at fine spatial resolution, and updateable on a relatively frequent basis