Detection, attribution, disintegration
Feb 20, 2013
Bishop Hill in Climate: D&A

James Annan hit the climate blog headlines the other day, with a post that not only wrote off the possibility of high climate sensitivities but also revealed that one climate scientist had been so sure of the omerta among his colleagues that he openly admitted to lying to promote political action on climate change.

Annan has now written another potentially blockbuster post, which discusses recent publications in the area of detection and attribution (D&A) - the bit of the climate change science that assigns guilt. What Annan reveals is that the studies that have supported the claim of "the majority of recent warming is manmade" are fatally flawed.

I've been fairly critical of the conventional D&A approach in the past, primarily on the grounds that the null hypothesis of no anthropogenic influence is always false a priori (and therefore a failure to detect an anthropogenic influence is always a matter of insufficient data). These recent papers point to another, arguably more terminal, problem. Attribution will inevitably fail as the anthropogenic effect increases!

Read the (relatively technical) reasons why here.

As Annan explains, this is going to leave D&A specialists with a headache to rank alongside the one being ensured by the climate sensitivity team.

It will be interesting to see how the D&A community addresses this problem. Atribution of the observed changes to GHG and other influences was touted as a major step forward when it was first achieved, so it would surely be rather embarassing to lose the ability to do this. It looks a bit like they are trying to just ignore it for now, but that can't really be tenable as a long-term strategy.

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