Category Archives: Uncategorized

Schmidt’s Histogram Diagram Doesn’t Refute Christy

In my most recent post,  I discussed yet another incident in the long running dispute about the inconsistency between models and observations in the tropical troposphere – Gavin Schmidt’s twitter mugging of John Christy and Judy Curry.   Included in Schmidt’s exchange with Curry was a diagram with a histogram of model runs. In today’s […]

Gavin Schmidt and Reference Period “Trickery”

In the past few weeks, I’ve been re-examining the long-standing dispute over the discrepancy between models and observations in the tropical troposphere.  My interest was prompted in part by Gavin Schmidt’s recent attack on a graphic used by John Christy in numerous presentations (see recent discussion here by Judy Curry).   Schmidt made the sort of offensive allegations that […]

Objective Bayesian parameter estimation: Incorporating prior information

A guest article by Nic Lewis Introduction In a recent article I discussed Bayesian parameter inference in the context of radiocarbon dating. I compared Subjective Bayesian methodology based on a known probability distribution, from which one or more values were drawn at random, with an Objective Bayesian approach using a noninformative prior that produced results […]

Marvel et al.: GISS did omit land use forcing

A guest article by Nic Lewis I reported in a previous post, here, a number of serious problems that I had identified in Marvel et al. (2015): Implications for climate sensitivity from the response to individual forcings. This Nature Climate Change paper concluded, based purely on simulations by the GISS-E2-R climate model, that estimates of […]

Bayesian parameter estimation: Radiocarbon dating re-examined

A guest article by Nic Lewis Introduction In April 2014 I published a guest article about statistical methods applicable to radiocarbon dating, which criticised existing Bayesian approaches to the problem. A standard – subjective Bayesian – method of inference about the true calendar age of a single artefact from a radiocarbon date determination (measurement) involved […]

Gerry Browning: In Memory of Professor Heinz Kreiss

Gerry Browning writes: The Correct System of Equations for Climate and Weather Models The system of equations numerically approximated by both weather and climate models is called the hydrostatic system. Using a scale analysis for mid-latitude large scale motions in the atmosphere (motions with a horizontal length scale of 1000 km and time scale of […]

Disappearing the MWP at Icefields, Alberta

In today’s post, I’m going to critically examine another widely used tree ring chronology: the Icefields (Alberta) MXD RCS chronology of Luckman and Wilson (2005 pdf), used most recently in Wilson et al 2016. I’ll show that the RCS technique used in the LW2005 MXD chronology eliminated high medieval values as a tautology of their method, not […]

New Light on Gulf of Alaska

Last week, I posted on the effect of ex post site selection on the Gulf of Alaska tree ring chronology used in Wilson et al 2016 (from Wiles et al 2014).  An earlier incarnation of this chronology (in D’Arrigo et al 2016) had had a severe divergence problem, a problem that Wiles et al had purported to […]

Marvel et al. – Gavin Schmidt admits key error but disputes everything else

A guest article by Nicholas Lewis Introduction Gavin Schmidt has finally provided, at the GISS website, the iRF and ERF forcing values for a doubling of CO2 (F2xCO2) in GISS-E2-R, and related to this has made wholesale corrections to the results of Marvel et al. 2015 (MEA15). He has coupled this with a criticism at […]

A Return to Polar Urals: Wilson et al 2016

Wilson et al 2016, like D’Arrigo et al 2006, includes a ‘Polar Urals’ chronology as one of its components.  Tree ring chronologies from Polar Urals and Yamal have long been a contentious issue at Climate Audit, dating back to the earliest days (see tags Yamal, Polar Urals). Whereas the D’Arrigo et al 2006 version had one […]