Responsible bodies such as the Intergovernmental Panel on Climate Change (IPCC) provide overwhelming scientific evidence for a dominant anthropogenic influence on climate over at least the past fifty years. However, there are still outspoken critics, from Donald Trump on down, who deny this reality. The typical criticism, rarely supported by any form of credible analysis, is this: the critics say that climate models are wrong and that, therefore, they cannot be trusted as a basis for policy. But are climate models wrong? Have predictions made by climate models in the past already turned out to be flawed?
This denial of the science is alarming because if we fail to take the science seriously and act too little or too slowly to ameliorate the perceived threat of future climate change, the consequences could be very serious. But there is another side to this coin: What if the magnitude of the threat has been overestimated? The uncertainties in projections of future climate change are large, and future changes could be either more or less than the central projections. The problem that policy makers are faced with, therefore, is how to act in the face of such uncertainty. Although my personal view is that it is better to err on the side of caution, treating mitigation and advance adaptation measures as insurance policies. However, the possibility of erring on the “too large a response side” is still of concern.