Climate Change and the Precautionary Principle

Risk Analysis Volume 25 Page 1399 - December 2005

Volume 25 Issue 6

Defining Dangerous Anthropogenic Interference: The Role of Science, the Limits of Science

Michael Oppenheimer*

Defining "dangerous anthropogenic interference with the climate system" in the context of Article 2 of the UN Framework Convention on Climate Change (UNFCCC) presents a complex challenge for those developing long-term climate policy. Natural science has a key role to play in quantifying vulnerabilities of elements of the Earth system and estimating the risks from a changing climate. But attempts to interpret Article 2 will inevitably draw on understanding from social science, psychology, law, and ethics. Here I consider the limits of science in defining climate "danger" by focusing on the potential disintegration of the major ice sheets as an example of an extreme impact. I show that considerations of timescale, uncertainty, and learning preclude a definition of danger drawn purely from natural science. Decisionmakers will be particularly challenged by one characteristic of global problems: answers to some scientific questions become less accurate over decadal timescales, meandering toward the wrong answer, a feature I call negative learning. I argue for a precautionary approach to Article 2 that would be based initially on current, limited scientific understanding of the future of the ice sheet. >>>>>>>>>>>>>>>>>>>>>>>>>>> BrooklynDodger comments: The Dodger hasn't been a fan of the precautionary principle, applied to occupational safety and health issues. For leading occupational issues, "decisionmaking in the face of uncertainty," is a false paradigm, what's really happening is refusal to act in the face of certainty. For example, the refusal to address poorly soluble particles with low toxicity in the occupational environment, following the wave of community studies. However, the Dodger concedes a continuum of precautiousness. At one end, if there's two bioassays, mechanistic information, and clear evidence of carcinogenicity in humans, there's sometimes a choice of model for high to low dose extrapolation. At the other end are persistent organic pollutants, where human health effects are thinly documented in the community and marginal in occupational setting [dioxin] but typically consistent with risks predicted from laboratory studies. The Dodger is impressed that somewhere on the other end is the debate over Genetically Modified crops, mostly an EU debate. Here there's little data for risk, other than fear of "messing with mother nature." [Although the defense of GMO is often a depiction of the damage done by non modified invasive species, which hardly reassures.] The GMO debate over precaution is somewhere in the area of "whether" there is a risk, almost at the level of hazard identification. Climate change is more about "how big" and "when" Anyway, Risk Analysis publishes about a 1:10 ratio of precaution to corporatist briefs. The paper cited above relays thoughts about doing something about global climate change which never quite reach a conclusion. Somewhere in the middle of th paper, Oppenheimer states a question but doesn't give an answer: The example of the ice sheets demonstrates three points: (1) the impact of ice sheet disintegration would be very large; (2) the risk from global warming cannot be quantitatively estimated as a function of local polar temperature because there is no ice sheet model that reproduces recent changes in the ice, and because the relation of local to global temperature changes is very uncertain; and (3) timescales over which disintegration may occur could be so long as to be irrelevant to most people, or could be short enough to make adaptation to resulting sea level rise very difficult. Uncertainties inherent in point (2) with regard to what amount of warming could trigger disintegration are so large that one approach that might seem reasonable to some people involves ignoring the problem altogether until understanding increases. Others would view the risk as demanding preemptive action despite the uncertainties. Similarly, the uncertainties in timing are so large that a range of judgments could be anticipated. The Dodger muses that climate change is mostly an economic impact, with health effects secondary to economic changes. Warming means more water in the ocean, heavily impacting where people live now, more rain falling on land but in different places than it is now.