Could we – or Should we – try to Solve Global Warming?

Inordinate contention attends complex socio-technical problems like global warming. The polarized extremes (end of the world versus good for us) are, I believe, the two lowest probability cases, yet they dominate media and political debates and editorial pages. No responsible scientist would claim to have precise expectations about our climatic future, its implications for nature and our lives or the costs of doing something about it. Nevertheless, a great deal of consensus exists about many aspects of the topic, despite the large uncertainties that accompany other components. In full recognition of the remaining uncertainties, a half-dozen pieces of circumstantial evidence were sufficient for the 100-scientist International Panel on Climate Change (IPCC) to assert in 1995: "nevertheless, the balance of evidence suggests that there is a discernible human influence on global climate". The 2001 IPCC assessment both reinforced the original claim of detection of an anthropogenic climate signal and brought to the forefront a new "discernible statement"— this time that recent observations of climate changes and the movements of wildlife, marine systems, ice extent and the timing of vegetation life cycles are becoming clear enough in the past few decades— the warmest in at least 1000 years— -that there now appears to be a discernible impact of regional climatic variations on natural systems. The prime implications of this new finding is that as the climate continues to change— and in most mainstream scientific studies that is expected to accelerate substantially in the 21st century— we can expect natural systems to become highly stressed. I will try to distinguish which are the well known components of the debate, contrast them to the over-contentious media/political debate, and put this problem in the context of so-called Integrated Assessment of policy responses to the advent or prospect of global warming. Finally, I will show that whether to respond to current levels of knowledge or to wait for more certainty is not a scientific judgment, but rather a value choice that is grounded in the risk proneness/aversion of individuals. Only if decision makers are aware of the range of plausible alternative futures and their relative likelihood can decision making be as informed as current science allows.