I don’t look at Anthony Watts’s blog, Watts Up With That (WUWT), very often, but I glanced at it today and noticed a guest post called four key charts for a climate change skeptic. Anthony Watts’s pre-amble says
Skeptics often get asked to show why they thinks climate change isn’t a crisis, and why we should not be alarmed about it. These four graphs from Michael David White are handy to use for such a purpose.
However, the rather amazing thing about the post (okay, maybe not that amazing) is that each one of the four key charts is deceptive and misleading.
The first chart purports to show 10000 years of climate change. Not only is it from a single site (an ice core from central Greenland – GISP2) but it is also presented as if it extends all the way up till today. However, the GISP2 ice core data is presented as years before present (BP) and the final data point is for 95 years before present. Also, before present in ice core data is actually relative to 1950, not now. This dataset actually ends in 1855 and so is not only for a single site (which would be expected to show more variability than the whole globe) it doesn’t even show any of our recent warming. If you consider what has happened in central Greenland since the mid-1800s, there appears to have been substantial warming. This Skeptical Science post explains all of this in quite some detail.
The second chart is intended to illustrate that climate models have failed by comparing model projections with observations. However, the chart indicates that we’ve only observed about 0.2oC of warming since 1980, and this is simply not true. Both surface and satellite datasets suggest that we’ve probably had at least 0.6oC of warming since 1980, which actually compares quite well with models. If anyone wants a fair comparison between models and observations there’s Realclimate posts for satellite and surface datasets. The comparison is clearly far better than the chart presented in the WUWT post.
The third chart is rather bizarre as it simply illustrates what happens if you change the y-axis scale. You can make the scale large so as to make the warming appear small, even though nothing has actually changed. The post actually says
To make your point or hide the truth you may change the representation of the data. Both of these charts show the same numbers.
It almost seems as if the author is suggesting playing with the y-axis scale so as to change the appearance of the warming. This seems blatantly dishonest, but maybe one should at least applaud the author for their openness.
The final chart is intended to illustrate the banality of climate change by comparing the last 140 years with the last 10000 years. The implication is that the climate has always changed and that the magnitude of the change we’ve recently experienced is nothing unusual. The comparison, however, is between global temperatures and – again – data from a single ice core in central Greenland. We expect much more variability locally than globally, so the comparison is clearly not fair. Furthermore, both datasets are plotted on the same graph, which makes the modern warming appear very slow in comparison to past changes.
Therefore, these clearly are not key charts for anyone who wants to be genuinely skeptical. If one is genuinely skeptical then one would like to see charts that don’t deceive and misrepresent. It’s one reason why the term skeptical is clearly not appropriate for anyone who promotes such charts. One could put inverted commas around skeptical as that would indicate a form of pseudo-skepticism, but even that seems generous. Other labels are, however, often criticised for being a form of unpleasant namecalling. However, if some are going to knowingly promote misleading charts, maybe they can’t really expect any better. It’s not as if doing so would somehow hamper genuine dialogue since genuine dialogue with those who promote such charts is almost certainly impossible.