Category Archives: Modeling

Guy Callendar vs the GCMs

As many readers have already surmised, the “GCM-Q” model that visually out-performed the Met Office CMIP5 contribution (HadGEM2) originated with Guy Callendar, and, in particular, Callendar 1938 (QJRMS). My attention was drawn to Callendar 1938 by occasional CA reader Phil Jones (see here and cover blog post by co-author Ed Hawkins here.) See postscript for […]

Results from a Low-Sensitivity Model

Anti-lukewarmers/anti-skeptics have a longstanding challenge to lukewarmers and skeptics to demonstrate that low-sensitivity models can account for 20th century temperature history as well as high-sensitivity models. (Though it seems to me that, examined closely, the supposed hindcast excellence of high-sensitivity models is salesmanship, rather than performance.) Unfortunately, it’s an enormous undertaking to build a low-sensitivity […]

Met Office Hindcast

In a recent post, I noted the discrepancy between the UK Met OFfice contribution to IPCC AR5 and observations (as many others have observed), a discrepancy that is also evident in the “initialized” decadal forecast using the most recent model (HadGEM3). I thought that it would be interesting to examine the HadGEM2 hindcast to see […]

More Met Office Hypocrisy

In yesterday’s post, I observed that Nature’s recent news article on Met Office decadal forecasts failed to show the most recent Met Office decadal forecast and that its inclusion would not have permitted the Nature headline. I also showed the large change from the Met Office submission to IPCC AR5 and their current decadal forecast. […]

Nature-mag Hides the Decline

Earlier this year, David Whitehouse of GWPF drew attention to a striking decrease in the UK Met Office decadal temperature forecast, that had been quietly changed by the Met Office on Christmas Eve. Whitehouse’s article led to some contemporary interest in Met Office decadal forecasts. The Met Office responded (see here); Whitehouse was also challenged […]

Non-centring in the Forest 2006 study

This is a cautionary tale, about a mystery that had an unexpected explanation. It’s not intended as a criticism of the scientists involved, and the problem involved, although potentially serious, actually had little impact on the results of the study concerned. However, I am hopeful that mathematically and computing orientated readers will find it of […]

New Nic Lewis Paper

Nic Lewis’s paper on climate sensitivity is available. See his BH post here. Also see discussion at Judy Curry and WUWT.

Mike’s AGU Trick

There has been considerable recent discussion of the fact that observations have been running cooler than models – see, for example, Lucia’s discussion of IPCC AR5 SOD Figure 9.8 (see here). However, Michael Mann at AGU took an entirely different line. Mann asserted that observations were running as hot or hotter than models. Mann’s assertion […]

Nic Lewis on Statistical errors in the Forest 2006 climate sensitivity study

Nic Lewis writes as follows (see related posts here, here) First, my thanks to Steve for providing this platform. Some of you will know of me as a co-author of the O’Donnell, Lewis, McIntyre and Condon paper on an improved temperature reconstruction for Antarctica. Since then I have mainly been investigating studies of equilibrium climate […]

Two Blogs on Climate Sensitivity

Two interesting blog posts on climate sensitivity. Troy CA here and Paul_K at Lucia’s here. I haven’t parsed either post, but both are by thoughtful commenters and deserve a read.

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