In the September 2009 edition of Nature, Rockstöm and colleagues proposeda range of essential Earth-system processes and their biophysical thresholds, or ‘planetary boundaries’, that, if exceeded, could lead to catastrophic environmental changes. Earlier this year, the planetary boundaries concept was accepted into the ‘Zero Draft’ of the Rio+20 conference as an essential element in negotiations toward setting environmentally related goals. However, following heavy scientific criticism, the concept was excluded from the Summit’s final statement in June.
The dismissal of planetary boundaries from the final Rio+20 text provides some implications for other environmental metric projects, including our work with the Environmental Performance Index (EPI). Here we address the arguments posed against planetary boundaries, which were recently reviewed by the staff at the Breakthrough Institute. Over the last decade we have incorporated many of these views into the EPI projects, and now we would like to offer some insight into our lessons learned. These experiences will be among the many we present in the upcoming release of our new “how-to” manual on developing environmental performance indices.
A huge challenge for many environmental metric projects is defining the goals and targets of the indicators they present. One of the major arguments from scientists is that planetary boundaries, or biophysical thresholds, are set subjectively, and humans, not ecological systems, determine the question, “How much is too much?” Research has shown that there are limits to an ecosystem’s capacity to absorb human impacts, and this understanding must be applied when defining a threshold or target. For example, we can only divert so much river water for irrigation before a river runs dry, and a plant can only take up so much nitrogen before the excess is washed away during a rainstorm.
Throughout our experience with the EPI, we have carefully considered setting limits and boundaries – constraints that may be viewed as subjective. We generally first looked toward global treaties or universally accepted goals for our indicator targets. We also obtained feedback from experts through discussions of existing data and policy needs, and we chose targets based on that guidance. While the targets of our index are not thresholds per se, they do allow countries to compare their performance toward the overall EPI goal of global improvement while providing data-driven support for policymaking.
Another major challenge for environmental metric projects is comparability between the types of issues they present. Scientists argue against the attempts of the planetary boundaries concept to compare local and global issues collectively. Is it adequate to compare a global issue, such as climate change, with more local issues, such as biodiversity, water, land and fertilizer? For a planet-wide standard, this may be a hard argument to win because many of the processes presented in these boundaries are not static around the world, and vulnerability to changes in these processes may vary geographically. But these are problems that should be examined everywhere, and it is important to consider what geographical scope is necessary for adequate comparability and applicability of a given project.
Several concepts of environmental change attempt to integrate costs and benefits into a framework, which ultimately is a decision that must be made with regards to a project’s objectives and metrics (e.g., examining human influence on environmental change or measuring progress toward a policy-defined environmental objective). Many times, changes in the environment with respect to human influence are often seen as negative. The authors at the Breakthrough Institute frame this as a problem with planetary boundaries – that they only measure environmental change as negative, and it is impossible for progression toward these boundaries to be positive. They argue that humans have benefited from many of these changes, and any framework attempting to measure environmental change must acknowledge these trade-offs.
The planetary boundaries framework also addresses ethics within science – arbitrarily setting numbers that “reflect preferred outcomes.” The planetary boundaries concept failed to make an explicit connection between particular outcomes and values. Without clarification of meanings and trade-offs between numbers, these thresholds suggest “what is” or “what ought to be,” therefore hindering the transparency of the project’s ethical commitments.
The EPI team takes great care in selecting appropriate targets that are transparent, supported by data, and globally comparable. The EPI is not trying to answer the question of ”how much is too much” because this is only a question that can be answered with human subjectivity (e.g., zero human impact is not possible without ceasing all economic activity, and any goal above zero impact would be determined by individual notions of how much harm is acceptable). Rather, we are hoping to provide a useful and transparent measurement of performance toward a specified policy goal using unbiased judgment and expert reasoning.
The arguments against the planetary boundaries framework have offered our team a chance to reflect on the lessons we’ve learned in our environmental performance measurement work over the years. Data-driven research is necessary for sound policymaking, and the failure to incorporate planetary boundaries into the final Rio+20 text has important implications for environmental measurement projects, especially with regards to measuring change, establishing limits or targets, comparability, trade-offs, and transparency.
Laura Johnson is a master's student at the Yale School of Forestry & Environmental Studies, where she is focusing on biogeochemistry and pollution analysis of aquatic systems. She is interested in the science and policy of environmental issues and their impacts on human health and welfare.