On Nov. 2, the United Nations’ Intergovernmental Panel on Climate Change will release its “Synthesis Report,” the final stage in a yearlong document dump that, collectively, presents the current expert consensus about climate change and its consequences. This synthesis report (which has already been leaked and reported on — like it always is) pulls together the conclusions of three prior reports of the IPCC’s 5th Assessment Report, and will “provide the roadmap by which policymakers will hopefully find their way to a global agreement to finally reverse course on climate change,” according to the IPCC chairman Rajendra Pachauri.
There’s just one problem. According to a number of scientific critics, the scientific consensus represented by the IPCC is a very conservative consensus. IPCC’s reports, they say, often underestimate the severity of global warming, in a way that may actually confuse policymakers (or worse). The IPCC, one scientific group charged last year, has a tendency to “err on the side of least drama.” And now, in a new study just out in the Bulletin of the American Meteorological Society, another group of researchers echoes that point. In scientific parlance, they charge that the IPCC is focused on avoiding what are called “type 1” errors — claiming something is happening when it really is not (a “false positive”) — rather than on avoiding “type 2” errors — not claiming something is happening when it really is (a “false negative”).