Recently Jos Hagelaars published a very extensive blog post (on the blog of Bart Verheggen) about a widely discussed paper of Klotzbach et al 2009. The title of the blog post – Klotzbach revisited – is in English, however, the post itself was written in Dutch. As a fellow Dutchman I understand that writing in Dutch is easier than writing in English. However, in this case, the blog post is focussed so much on one single paper, that Jos Hagelaars, in my opinion, should have chosen for an English version, in order to give the authors of the Klotzbach papers the chance to give a reaction. I translated the article with google translator and did some minor editing. I then shared the article with a few of the coauthors. John Christy looked at some of the issues raised by Hagelaars and wrote the following reaction which I publish here as a guest blog.
Guest blog by John Christy
In a blog post entitled “Klotzbach Revisited” Jos Hagelaars updated the results of Klotzbach et al. 2009, 2010, suggesting that the main point of Klotzbach was no longer substantiated. Klotzbach et al.’s main point was that a direct comparison of the relationship of the magnitude of surface temperature trends vs. temperature trends of the troposphere revealed an inconsistency with model projections of the same quantities. Klotzbach et al. offered suggestions for this result which included the notion that near-surface air temperatures are easily affected by factors unrelated to greenhouse gas increases, which then implies they may be poor proxies for detecting the magnitude of the greenhouse effect which has its main impact in the deep atmosphere.
It appears Hagelaars’ key point is that when the data from Klotzbach et al. are extended beyond 2008 to include data through 2012, the discrepancies, i.e. the observed difference between surface and tropospheric trends relative to what models project, are reduced somewhat.