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Net Positive Impact: The Science Question for Today’s Conservation

Peter Kareiva 10/1/2012

Businesses and NGOs (including TNC) with strong commitments to sustainability often announce a goal of “net positive impact” (NPI) for activities such as mining or natural gas and oil pads. At first glance, this goal seems absurd — how could the activities of extractive industries have a net positive impact on the environment?

But once you understand how NPI might work, you also understand how the concept leads to probably the most important suite of scientific questions for today’s conservation. When industry mines, drills, dams, erects windmills or builds roads, the quality of local habitats is almost certainly degraded. But if the places where these activities happen are already degraded, and if we work with industry to invest elsewhere in restoring or protecting habitats critical for biodiversity and ecosystem services, then the balance sheet could turn out pretty well. All we need is the science to figure out how to accurately calculate that balance sheet.

The problem is: we almost never have the science. For example, what is the rate of biodiversity or ecosystem decline for each windmill, mine or road added per 1,000 square miles? Are there thresholds of activity or exploitation that, once crossed, lead to a total ecosystem unraveling? And how do we address the possibility of cumulative small impacts that sneak up on us and ultimately end up producing unacceptable degradation? These are just some of the questions to which we lack answers.

Traditional conservation biology focused on the placement, size and management of protected areas. We know that protected area science is not enough, given the scale of human activity today. So today’s conservation biology needs to focus on fracking, wind farms, mines, roads, transmission lines and hundreds of other human activities and their footprints. The research will not be about “yes” or “no” — it will be about where and how much, and about what can we do to recover or offset.

We will make mistakes as we take action. We might allow what we think is the correct amount of logging, grazing or windmills — only to learn in 20 years that ecosystems have been damaged more than we had hoped. The sin will not be in the mistake — the sin will be if we have not been gathering the type of data needed to learn from the mistake. And herein lies the challenge: Suppose you wanted to maintain grasslands as intact — what would you measure to determine whether or not they remained intact after different human intrusions?

The good news: Even if we make mistakes, there is much evidence that ecosystem recovery is possible, and sometimes even likely (Jones and Schmitz 2009, Lotke et al 2006). The bad news: outside of agriculture (where there are several studies comparing land sparing to wildlife friendly practices), I know of no large-scale concerted scientific analyses that quantify the dose-response curves for extractive activities or infrastructure deployment versus ecosystem services or biodiversity. The smart development efforts of conservation NGOs (such as TNC’s Development by Design and Smart Infrastructure initiatives) offer a tremendous opportunity for basic science studies that can provide the foundation for the new work of conservation.

But by “basic science studies” I mean actually collecting data in the field, as opposed to assuming that because the maps look right, all is OK. I will be skeptical of NPI until I see field data of species richness increasing or ecosystem services on the rise as compared to control sites. A coalition of different NGOs and their smart development projects could become the test cases of a much needed meta-analysis. Anyone interested in pursuing this with me — email pkarevia@tnc.org.


Jones, H.P., and O.J. Schmitz. 2009. Rapid recovery of damaged ecosystems. PLoS One 4(5) http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0005653

Lotke, H.K. et al. 2006. Depletion, degradation and recovery potential of estuaries and coastal seas. Science 312:1806-1809.