Study: Climate Skeptics Arguments are Demonstrably False

The argument structure is something like this:
Premise one: The climate has changed in the past through natural processes
Premise two: The climate is currently changing
Conclusion: The climate is currently changing through natural processes.
…
The syntax conveys the impression that the argument is valid, but it is not.

If this is taught in a university course on critical thinking, UQ is in big trouble.
Nit pick: The “syntax” is simply whether it follows the rules of English sentence construction, and can convey nothing beyond the fact that the writer can write English sentences. Nitty picky, yes, but a lecturer in critical thinking should get it right because it matters in that very discipline.
Serious point 1: Let’s replace “syntax” with something that makes some sense of the passage, say, “argument form”. Well, no. It does not convey any impression of validity to anyone with a competent knowledge of logic. Consider:
Traffic lights have changed in the past from red to green.
That traffic light is changing.
Therefore it is changing from red to green.
Serious point 2: Climate skeptics do not make this argument anyway, they say it is up to the alarmists to provide evidence that the null hypothesis is false. The entire presentation slyly assumes that it is the job of the skeptic to disprove an unfounded claim.
Serious point 3: Straw man. This is not even one of the serious arguments advanced by skeptics. Amongst the main ones are:
A. If the theory were correct there would be a “hotspot”; there isn’t; therefore the theory is false.
B. If the theory were correct there would be more water in the troposphere; there isn’t; therefore the theory is false.
C. If the theory were correct there would be less radiation escaping to space; but there is actually more; therefore the theory is false.
Serious point 4: factual error: The climate has both warmed and cooled faster in the past than it is now.
All in all typical of what I have sadly come to expect from my (embarrassment!) alma mater.

Current climate change is much more rapid than previous climate change – they are not the same phenomenon.

The phrase, “climate change” describes a category of change, where the category described does NOT change. The category is the category, like a cat is a cat, whether it was a cat that lived a thousand years ago or a cat that was just born after I put the period at the end of this sentence.
Qualifying climate change as “current” or “previous” is a secondary operation that delineates a different feature than the base categorical description. Speaking of “current climate change” and then asserting that this QUALIFIED category is “much more rapid” is itself an unproven statement begging the question (as someone above said), which the author is trying to use to substitute for the base category label, “climate change”.
In effect, the author is trying to use an unproven claim to qualify a base category label and then use this unproven, qualified category label as a replacement label for the original category label. In other words, the author is trying to replace “climate change” with “current climate change more rapid than previous climate change”. The latter is unproven, thus, he is trying to replace a general label with an unproven claim.
I, thus, call bullshit sophistry on this “strategy”. [Note the crescendo of scholarly elegance in my final sentence.]

Ellerton’s representation makes a claim which arises repeatedly in the alarmist claims, namely that “the climate” is changing “faster” than it ever has in the past. What is glaringly absent from such claims is what is used to define “climate” and with that any meaningful measure of past rates of “change”. By “climate” does he mean windspeed, mean global precipitation, duration of growing seasons, or that most abused and foggy of metrics, “mean global temperature”? Since thermometers have existed only since the late 17th century, and contiguous monitoring of the temperatures at earth’s extremes such as the polar regions has only occurred since the international geophysical year in 1957, I am hard pressed to imagine how one would determine the rate of change that occurred in even one (very dubious) metric between say, for instance the height of the Roman warm period and the cooling that occurred prior to the rewarming known as the mediaeval warm period. The measurement tools necessary to obtain the degree of resolution required to make meaningful comparisons simply didn’t exist until the very recent past.

John Cook is the tip of the spear in the ongoing war on truth and science. His success is remarkable, given that his key arguments collapse completely and immediately under even mild scrutiny, as has been ably point out in comments here.
Cook et al 2013 misleadingly reported they sought to measure the scientific consensus on dominant AGW, but careful reading reveals that, instead, they included those who merely said, or even just implied, that AGW was more than zero, with no limit to how small. This shameless trickery established the complete lack of credibility of Cook, his co-authors, and the “journal” Environmental Reasearch Letters. It also demonstrated the fallibility of peer-review. It is sad, although no longer surprising, that someone entrusted to teach critical thinking would choose to join Cook as a comrade in arms in the war against truth and science.