By Andy May

Tinus Pulles critique of our paper begins by admitting that, at present there are no adverse effects from climate change, but that we ignored possible future climate change effects. This was deliberate, as we wanted to deal only with established and observed facts and data. Climate model projections of the effects of climate change are highly speculative because the climate change models they use as input are incorrect and project too much warming as documented in the paper and in AR6 (McKitrick & Christy, 2018), (McKitrick & Christy, 2020), and (IPCC, 2021). I do not think there is any need to respond to projections from the critique.

Pulles seems to be concerned that I equate “dangerous” and “damage beyond our ability to adapt.” But they appear to mean the same thing to us.

He seems concerned that the Little Ice Age did not occur everywhere at the same time, and is barely observable in Antarctica, see figure 1.

No climate change event is synchronous around the world, that is also true of modern warming. Over the past century, Antarctic temperatures have barely changed as can be seen in figure 1 and in figure 13 here also shown as Figure 2. Climate change occurs by latitude mostly, although Atlantic/Pacific changes are different as well, this is an indication that CO2, which is global, is not very important.

Figure 1. Holocene proxy temperatures in Greenland, the Makassar Strait in Indonesia, and in Antarctica. The Little Ice Age is barely visible in Antarctica and the maximum cooling in the Pacific and in the Atlantic occurs at different times

Figure 2. Recent Antarctic Temperatures. From here

Pulles acknowledges that AR6 shows that present levels of global warming are moderate, but claims experts project that that will not be the case in the future. The IPCC’s AR6 admits that their models run too hot, and that the AR6 models are worse relative to observations than the AR5 (2013) models were. Their models are getting worse with time, so their projections should not be believed. When new versions of a model get worse, it is a sure sign that the premises the models are based upon are wrong (see here and here).

“We assess with medium confidence that CMIP5 and CMIP6 models continue to overestimate observed warming in the upper tropical troposphere over the 1979–2014 period by at least 0.1°C per decade, in part because of an overestimate of the tropical SST [sea surface temperature] trend pattern over this period.” AR6, p 444

“… despite decades of model development, increases in model resolution, and advances in parametrization schemes, there has been no systematic convergence in model estimates of ECS. In fact, the overall inter-model spread in ECS for CMIP6 is larger than for CMIP5; …”AR6, WGI, page 1008.

Pulles claims that the anomalous cooling from 1944-1978, as CO2 was increasing, was due to increasing industrial pollution. Very speculative and he offers no references or data to support this idea. I’ve seen this idea bandied about before, but I’ve seen nothing but speculative models that support it.

He disputes our statement that most of the evidence that humans change the climate comes from models, by citing evidence that comes from models! Then he claims, against all evidence, that the models are accurate. Amusing.

The next several comments are clearly incorrect or irrelevant and not worth messing with.

Then we get to this, Pulles writes “Even if these effects may not exceed natural variability, [this is not proof they will not be in the future.]” The bit in square brackets is paraphrased to make it easier to read. So, Pulles is admitting to the possibility that nothing outside natural variability has occurred yet but might according to climate models that have been shown to be erroneous. This supports the central point of our paper.

Pulles claims that plotting log(CO2) versus temperature shows an acceptable correlation and tries to use the R2 to show that only 10% of the variability in temperature is left unexplained. However, both the CO2 record and the temperature record are autocorrelated and the R2 statistic between two autocorrelated series is invalid.

His next comment is a question, and he seems to not understand what the AMO index is. This is described in detail in (Kerr, 2000) and (Gray, 2004) in the bibliography for the paper. He should do his homework before writing a critique. The following two comments only reveal his ignorance of the AMO and statistics, I’ll ignore them.

The next comment is on trends in extreme weather, but it is transparently nonsensical. One-year changes are not significant, and we reject projections into the future. Right now, extreme weather is not increasing globally. Of course, it will always increase and decrease locally. Some areas benefit and others suffer, that is how weather works

The remaining comments are irrelevant to the paper, transparently incorrect, or already dealt with above. I see nothing in this critique that invalidates anything in our paper, but feel free to read Pulles comments and decide for yourself.