Ian Plimer is a professor of Geology at the University of Adelaide in Australia, specializing in mining geology. This book, his view of the science of climate change, is a difficult read, with a large number of footnotes sometimes taking up half the page. The text often wanders, perhaps to use up some of the references he has accumulated. For readers unfamiliar with climate science, or science in general, this may create an impression of an expert author with a vast array of evidence to back up his writing, which is not necessarily the case.
The History chapter, the one closest to his actual expertise, is a detailed account of the many changes that have occurred in climate, mainly over the past few thousand years. Unfortunately, that history is not known to nearly the same level of detail in which it is presented. As in any science, there is much debate and uncertainty about the magnitude and timing of these events. Throughout the book Plimer rarely gives any hint to any such uncertainty.
According to Plimer's account, every plague or collapse of a civilization was directly caused by a climate change event. In reality, there is much debate among historians about the role of climate change, and it is only sometimes considered to be a contributing factor. The extreme climate determinism here is rather curious, given that it is usually those concerned with anthropogenic climate change who invoke images of civilizations collapsing due to climate.
The historical events do not always align with the climate changes that supposedly caused them. For example, the decline of the Roman Empire began well before the peak of the Roman Warming. Contrary to Plimer, the "Dark Ages" was not a climatic period, or even a "terrible time to be alive." Rather, its causes were internal political and external military pressures on the Roman Empire and its successors. The extreme events he describes appear to be a single volcanic eruption (with "meteor and comet swarms" no less), not the general climate of the period. Rather than people starving, agriculture became more productive due to the invention of a superior plow. If Europe was freezing in the dark, why did the center of power migrate northward from Italy to France, then to Germany during this period?
A statement such as "by 300 AD the global climate was far warmer than at present" is misleading because only the European climate is known in any detail. A regional climate change often has only a small global impact. The 1977 book used as a reference (instead of the 1995 version, available for free online) could not have had any information on the global climate of the period. But although much of the detail is wrong, the general picture of a variable climate in the past is valid. In particular, warming climates are often (not always) associated with improved agriculture, while cooling often leads to droughts and stormy weather. An informed and balanced discussion of the relevance of this to a warming climate in the future would be welcome, but it is not to be found here. Instead we get told the false dichotomy that because climate changed naturally in the past, human caused change is not possible in the future.
As another example of the quality of the references, on page 59 we are told that during the Roman warming "tropical rains in Africa caused huge flooding of the Nile and many great buildings were inundated. These changes in rainfall, river flow and lake levels were widespread." If you bother to scan down to read the two references given, one is a paper on the prairies in North America, the other is about the west coast of Spain and Portugal. In general, references tend to be given for minor items, while major and controversial statements get none.
The remainder of the book, departing ever further from his expertise, is about promoting all possible causes of climate change except carbon dioxide. Extreme and unsubstantiated statements are common, such as "there is no such thing as the greenhouse effect," or there is no correlation between carbon dioxide levels and global temperature. In fact, there is a good correlation wherever there is reasonably certain data on all but the shortest time scales. So on page 26 we are shown a chart of temperature compared to carbon dioxide levels, and are told "this diagram shows that the hypothesis that human emissions of CO2 create global warming is invalid." This chart covers a six year time span. Any trend can be generated by cherry picking the right six years, as any practicing geologist should know. Similarly, no mathematically literate scientist could make the extraordinary statement on page 361 that "in Australia, 40 major floods were recorded from 1900 to 1982. Of these, 24 occurred during the first cycle of a double sunspot cycle and 16 in the second cycle, again showing the very strong relationship between solar activity and climate." This small amount of data has no statistical significance.
An example of the desperate attempt to find any cause of warming other than carbon dioxide is found on page 209, "as the oceans contain 22 times more heat than the atmosphere, ocean heat contributes greatly to driving climate and the unseen submarine volcanism can have a profound effect on the surface heat of the Earth." In fact, the oceans contain one thousand times more heat than the atmosphere. As for under-sea volcanoes affecting the climate, the reference he gives is a 1979 paper on a single submarine volcanic vent system. The paper only says (imagine, actually checking a reference!) the plume becomes undetectable 150 meters above the bottom. It is only examining the effect of the heat on local biology, not the global climate.
But the ultimate departure from reality is found on page 416, "between 1812 and 1961, there have been more than more than 90,000 measurements of atmospheric CO2 by the Pettenkofer method. These showed peaks in atmospheric CO2 in 1825, 1857 and 1942. In 1942 the atmospheric CO2 content (400 ppmv) was higher than now." The reference is to a non peer-reviewed journal. If there was any truth to this, the entire case for global warming would be falsified, and the rest of the book would not be necessary. But (almost) no scientist, even those most skeptical about global warming, would take this nonsense seriously.
My question is, how can a scientist with a good reputation in his own field write a work that is so full of errors and every possible class of logical fallacy? The examples I give are representative of what is found on almost every page, backed by a horde of references that do not actually support his statements. This is the pseudo-science of a post-modern artist, for whom facts are merely the raw materials to construct a personal fantasy of both what climate science is, and the data that may or may not support it.
This book may be of use someone who is looking for examples to make critics of climate change look foolish. Those looking for "ammunition" to support a preconceived view that global warming is a complete fraud may also think this book useful, but consider the consequences of making a "Pettenkofer method" type of statement to an informed audience. Anyone who actually wants to understand more about the global warming controversy is advised to look elsewhere.