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The State of Ecological Footprint Science

This article was written by Alex Lowe in June 2007. We're republishing it here as part of our month-long editorial retrospective.

EFN.jpgTo understand the subtleties and difficulties in ecological footprinting, think of accounting. In the past few years, Enron's collapse and the scandals that surrounded WorldCom gave people a small glimpse into the intricacies of accountancy. To the uninitiated, the swirl of news reports circa 2003 must have posed several questions: How hard can accounting really be? How can any grey areas exist in an activity as seemingly concrete and dry as counting beans?

But grey areas abound, and the task of accounting for nature's resources as well as their depletion from human demand is, to use the colloquial, a doozy. How can one compare the value of a single fish to that of a bushel of corn or a California redwood? How does that relationship change from the exhaust pouring out of your car or the dishwater circling your drain?

The methodology for answering these questions in ecological footprint analysis (EFA) is often criticized for being incomplete and for underestimating humanity's true impact on the environment. In response, researchers at Redefining Progress have made several amendments to the standard methodology, and given their creation the handle 'Ecological Footprint 2.0.' (Best explained by the paper Footprint of Nations, 2005 Update.)

The first improvement that Redefining Progress made is including the total surface area of the earth to estimate biocapacity, whereas the earlier methodology (hereafter called 'EF 1.0') used only the accessible regions and, most glaringly, left out the open ocean. EF 2.0 also sets aside 13.4% of the world's biocapacity for wild species. This number comes from a procedure called global gap analysis and reflects the amount of biocapacity needed for 55% of significantly threatened species to survive. EF 1.0 assumed that humans would occupy every last bioproductive hectare which leads to an artificially smaller ecological footprint and leaves no room for other species. In other words, the future envisioned by EF 1.0 has precious little work for nature photographers.

EF 2.0 also diverges from EF 1.0 in estimating the global food supply. EF 1.0 uses estimates of potential agricultural productivity furnished by the Global Agricultural Ecological Zone (GAEZ). Potential agricultural productivity measures the potential yield of food-energy from farmland in kilo-calories. While widely used, some researchers criticize this method because of its discrepancies with measurements of actual yields, such as those calculated in certain parts of Africa where actual production was significantly lower that potential production. EF 2.0 calculates the total amount of energy stored in a food source and subtracts the respiration of primary producers. This technique, called net primary productivity (NPP) estimates the full amount of available food-energy, and is a more accurate procedure for footprint needs than EF 1.0's potential agricultural productivity.

Other researchers have added to the standard EF 1.0 methodology in different ways. Experts at the Global Footprint Network have improved estimates of the footprint that international trade creates by making use of the U.N.'s COMTRADE database, which tracks more than 600 products as they move between nations. These experts have also made the leap of reporting time-trends in the Living Planet Report 2006 in units of constant 2003 global hectares. This improvement 'adjusts for inflation' so that people can compare the bioproductivity of two different years on the same scale.

The UK's Best Foot Forward research group throws two trademarked methodologies called 'Stepwise' and 'EcoIndex' into the mix, which break down the data from the National Footprint Accounts into several "categories of impact," including direct energy, materials & waste, food & drink, personal transport, water, and built land. Each of these categories can be further reduced to smaller components which let experts zero in on which objects and behaviors in everyday life press down on the environment with the most relevant footprints. For example, the study City Limits focused on the footprint of London and found that eating meat has a footprint of almost six million gha, over 24 times the size of fruit's footprint. If Londoners swore off meat, that change alone would decrease their footprint significantly.

But there are other ways that future research could refine these methods. For example, still missing from EF 2.0 and other methods is a way to account for the footprint of myriad other pollutants besides carbon. Presently, carbon is the only pollutant that ecological footprints consider. (Not surprising, considering the gravity of global warming) But there are many other pollutants that have significant deleterious effects on the environment, such as dioxins, mercury and endocrine-disruptors. With countries such as China and India growing massively in their production, these pollutants will make their impact felt by the environment as well as human health. Some pollutants, like radioactive waste, are not absorbed by the environment at all, and more refined measures must also take them into account. The work also excludes behaviors that harm ecosystems' future health, such as soil erosion and overfishing. Hopefully this will be one of the directions that research takes as scientists around the world improve their estimate of humanity's footprint.

Ecological Footprint 2.0 is part of our month long retrospective leading up to our anniversary on October 1. For the next four weeks, we'll celebrate five years of solutions-based, forward-thinking and innovative journalism by publishing the best of the Worldchanging archives.

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