Reply to Comment on "Using multiple observationally-based constraints to estimate climate sensitivity by Annan and Hargreaves (2006)" by Henriksson et al. (2010)

Henriksson et al. (2010), hereafter HALTL10, criticise Annan and Hargreaves (2006a) (AH06) primarily on the grounds that we assumed that different sources of data were conditionally independent given the climate sensitivity. While we consider this approximation to have been a reasonable one in the circumstances (and provided arguments to justify this approach), we also acknowledged its importance in our original paper and performed several sensitivity analyses. The alternative calculations presented by HALTL10 appear to strengthen rather than contradict our conclusion. HALTL10 additionally criticise Annan and Hargreaves (2009) (AH09) for proposing a Cauchy-type prior (as an alternative to the use of a uniform prior which was widespread up to that time) "without sufficient support'', and further claim that our choice was irrationally based on an economic assessment. We are surprised by these baseless claims, especially considering that the proposed prior was justified at some length both on the basis of both the "Charney report'' (National Research Council, 1979) and basic physical arguments, and also in light of our elementary demonstration of the pathological failings of the most commonly-used alternative. Thus, these claims are factually incorrect.