It is claimed by Rickova and Irsova, in a paper titled "Publication Bias in Measuring Climate Sensitivity" [A], that:
We present a meta-regression analysis of the relation between the concentration of carbon dioxide in the atmosphere and changes in global temperature. The relation is captured by “climate sensitivity”, which measures the response to a doubling of carbon dioxide concentrations compared to pre-industrial levels. Estimates of climate sensitivity play a crucial role in evaluating the impacts of climate change and constitute one of the most important inputs into the computation of the social cost of carbon, which reflects the socially optimal value of a carbon tax. Climate sensitivity has been estimated by many researchers, but their results vary significantly. We collect 48 estimates from 16 studies and analyze the literature quantitatively. We find evidence for publication selection bias: researchers tend to report preferentially large estimates of climate sensitivity. Corrected for publication bias, the bulk of the literature is consistent with climate sensitivity lying between 1.4 and 2.3C.
Is this true? A paper titled "No evidence of publication bias in climate change science", written by Christian Harlos, Tim C. Edgell & Johan Hollander [B], appears opposed, but finds that while
Our meta-analysis did not find evidence of small, statistically non-significant results being under-reported in our sample of climate change articles
it did find the following:
However, our meta-analysis did find multiple lines of evidence of biases within our sample of articles, which were perpetuated in journals of all impact factors and related largely to how science is communicated: The large, statistically significant effects were typically showcased in abstracts and summary paragraphs, whereas the lesser effects, especially those that were not statistically significant, were often buried in the main body of reports. Although the tendency to isolate large, significant results in abstracts has been noted elsewhere (Fanelli 2012), here we provide the first empirical evidence of such a trend across a large sample of literature.
We also discovered a temporal pattern to reporting biases, which appeared to be related to seminal events in the climate change community and may reflect a socio-economic driver in the publication record. First, there was a conspicuous rise in the number of climate change publications in the 2 years following IPCC 2007, which likely reflects the rise in popularity (among public and funding agencies) for this field of research and the increased appetite among journal editors to publish these articles. Concurrent with increased publication rates was an increase in reported effect sizes in abstracts.
Similar stylistic biases were found when comparing articles from journals with high impact factors to those with low impact factors. High impact factors were associated with significantly larger reported effect sizes (and lower sample sizes; see Fig. 4); these articles also had a significantly larger difference between effects reported in abstracts versus the main body of their reports (Fig. 3). This trend appears to be driven by a small number of journals with large impact factors; however, the result is consistent with those of supplementary studies.
and also shows in Figure 3: that when their sample includes all journals (which is required per their above finding that journals with a high impact factor selectively publish larger results), the Climate Sensitivity is estimated at 1.6C per doubling of atmospheric C02.
PS: I found this blog to give a better overview of the claim than I can: http://grokinfullness.blogspot.com/2017/04/publication-bias-in-climate-science.html