I had never intended this blog to be about climate science, but every now and again something comes along which changes that. Recently that something was a book by an Australian geologist, Ian Plimer, Heaven and Earth – global warming the missing science. The book sets out to deconstruct every single aspect of climate change science (even to the point of arguing that CO2 levels may not actually be rising). The book cites over 2000 scientific papers. It was sent to me by a colleague who I have known for many years – other colleagues also received copies from the same person. Added to this was the fact that the author comes from Adelaide University, where I studied chemical engineering. So I feel compelled to reply.
There is no doubt that this is a very heavily researched book, quoting over 2000 sources and scientific papers. The papers quoted, as far as I can tell based on the ones that I recognise, represent the peer reviewed findings of scientists from around the world, but I think Plimer has been somewhat disingenuous in the way he has picked pieces from a variety of papers on a subject, quoted them all en masse, but then not actually represented the full findings of those papers in the text that he writes on a given subject. I can only come to this conclusion based on papers I actually know and that sample represents a small fraction of the totality of papers cited, but I am concerned that this approach may be common throughout the book.
This is best illustrated with an example. On pages 405 to 410 Plimer discusses hurricanes and as is typical throughout every other part of the book seeks to deconstruct so called popular thinking about this issue in relation to climate change. He claims that tropical hurricanes and cyclones are not increasing in number, that there is no change in strength linked with temperature rise and that any variation we may have seen in hurricanes is due to a multi-decadal oscillation that exists as a background to hurricane activity. He twice quotes (and I am sure correctly) papers published in Natureby Dr Kerry Emmanuel, a well known researcher into this subject. I had the privilege of listening to a presentation by Dr Emmanuel on this paper and what was said in person bears little resemblance to the conclusions Plimer comes to, even though the paper is mentioned. Rather, Dr Emmanuel presented statistical evidence that hurricane strength is increasing as the oceans warm and that this is unrelated to any background oscillation. They did concur on the point that the number of hurricanes appears to remain the same globally, although Plimer puts “increasing numbers of hurricanes” forward as an issue that needs debunking, rather than an issue on which there are either no findings or possibly just a media finding.
It also appears to me that there is a faulty logic running throughout the book. It runs something along the lines of “I grow yellow flowers in my garden, this is a yellow flower, therefore it must have come from my garden”, or perhaps an alternative along the lines of, “When I last looked in my garden there were red flowers, this flower is yellow, therefore it couldn’t have come from my garden.” Over and over the reader is reminded that because certain sets of conditions have existed in the (long distant) past that we can’t be in the situation today where rising levels of CO2 can be linked with any change in temperature. For me this isn’t a valid argument. I can well imagine any number of steady states existing at quite different combinations of CO2 level and temperature, driven by the position of the continents, the type of biosphere at the time, orbital variation, solar activity and so on.
Other arguments seem just plain wrong. For example, he makes a constant mockery of Al Gore and his matching saw tooth graphs of CO2 and temperature. With hindsight, I suspect even Al Gore would probably agree that this wasn’t the best example to use, in that at least part of the phenomena he was highlighting is most likely CO2 degassing of the oceans as temperature rises (e.g. as a result of orbital variation) rather than rising CO2 driving temperature. There is a multi-century time lag involved for rising temperatures to lead to significant ocean degassing, simply because of the size of the oceans and the rate at which they take up heat. But Plimer then goes on to link (as a possibility) the current rising CO2 level (which in other parts of the book he even refutes is happening) to the Medieval Warm Period. Surely CO2 degassing will only take place after many hundreds of years of constant warming, i.e. a constant higher heat flux into the ocean, not as a delayed response to a temporary warming blip some 700 years ago, following by a cold period as well. This seems like pretty basic heat transfer thinking to me.
Perhaps the weakest part of the book is the discussion around CO2 absorption in the infra-red, which of course is critical to the whole issue. Having cited endless papers on everything else, he finally gets to this key point and cites almost nothing at all. He claims that the greenhouse gases that already exist in the atmosphere absorb most of the infra-red which means there is nothing more to absorb so there need be no fear of rising levels of greenhouse gases. I have spoken to colleagues who study the science very carefully and external climate scientists and this issue has long been put to rest. The reality is the opposite, i.e. that rising levels of trace gases are contributing to increased infra-red absorption. More importantly, the trace gases are driving (forcing mechanism) the change as they accumulate in the atmosphere, whereas water vapour, which Plimer talks about as the only greenhouse gas that really matters, is responding as a feedback mechanism with rising temperature. Water can only ever act in this way as it cannot accumulate in the atmosphere. If there is too much it rains. It is even possible to see all this from satellite data, which shows the difference in absorption spectra as seen from above our atmosphere over the period 1970 to 1997 (although presumably Plimer wouldn’t like this study as quite a bit of data processing has been done – seems to be a pet hate of his).
One other issue that particularly bothered me is his criticism of the measurement of CO2 and his claim that CO2 levels in the atmosphere have been much higher even in recent times. He notes that 19th Century CO2 measurements show periods at over 400 ppm, so why worry now about 390 ppm and rising. The reality is that since the late 1950s a very accurate system of global monitoring of CO2 levels has been put in place. These CO2 measurements are done in remote locations based on the techniques developed by Charles David Keeling. The measurements represent the background CO2 level of the atmosphere, not some local spot number. Local spot data can vary significantly for all sorts of reasons and is the most likely contributor to significant variations in atmospheric CO2 levels reported over the last 150 years. Plimer doesn’t even discuss this. More recently, ice core data has shown that the long term background level is very stable during inter glacial periods.
It is also important to mention another Plimer perspective – this is where he seems to get angry. He relentlessly attacks the IPCC as if it were a monolithic block of scientific thinking that is intolerant of any findings that deviate from “climate doctrine”. That is far from any reality I have seen. Whilst nobody would claim IPCC is perfect or free from political interference, it is a body that seeks to pull together peer reviewed literature, not generate such material itself. For example, IPCC have no computer climate models, although Plimer constantly refers to the “IPCC models” and their “doubtful findings”. Rather the models exist in the various research institutions that IPCC draws on. On the subject of political interference, demonisation of sceptics and witch hunts (of climate sceptics) I suspect that some scientists would claim the opposite, i.e. that their disturbing findings on what we are doing to our atmosphere and the impact that will have, were undermined by some governments in recent years. I have heard first hand such sentiments expressed from the podium in scientific gatherings.
Over a period of about ten years now Shell has supported the MIT Joint Program on the Science and Policy of Global Change. The researchers there also contribute to the IPCC process and they have an increasingly sophisticated climate model. In the time that I have been attending the meetings there has been a steady progression of new findings and advances in many fields, including aspects such as clouds, aerosols, volcanoes and the like, all of which contribute to the overall thinking on the climate issue. The MIT forums do not seek to promote climate scientists nor to demonise those that have alternative view points, rather they serve to discuss findings and promote thinking and understanding of the issues we face. I am at a loss to understand why Ian Plimer has set out to invalidate everything that such people have contributed and why he thinks that his view of this issue is the correct one, let alone that all others are simply wrong.
Finally, let us not forget the political reality of all this. Governments in all parts of the world are acting on the issue of climate change. For this and many other reasons, some good and some not so good, they want to see a shift in the make-up of the energy system and the way in which we use energy. It is hard to see that the energy status quo will persist, even despite the Ian Plimers of this world.
As for a book I would recommend, try The Long Thaw, by David Archer. It is based on many of the same papers that Plimer cites, but perhaps not surprisingly the conclusion is very different.