THE HOCKEY STICK AND THE CLIMATE WARS
This book was better than I expected. My expectation was based not on Mann’s reputation/caricature, but on his previous book “Dire Predictions” co-authored with Lee Kump which we have reviewed previously.
On this site and in blog contributions I’ve recently been trying to promote two themes. The first is that the climate science community is weakening its case by trying to ignore inconvenient facts and data; it then gets doubly blamed for the cover-up and the inconsistency between their claims and the data. The second theme is that when presenting climate science to a largely lay audience, as Mann does here, a scientist has to be more careful than in a published paper. A paper will be thoroughly scrutinised by other scientists; lay people will not know if the wool is being pulled over their eyes.
Much of the book deals with the ‘climate wars’ aspect of title and the fact that few attacks on climate scientists fail to include Mann or his ‘Hockey Stick’. In the USA the whole issue of climate is much more divisive than in the UK. In the UK the Climate change Bill, mandating a reduction of 80% in CO2 emissions by 2050, was passed with only 5 votes against. At a recent lecture the Director of the Grantham Institute for Climate Change, Sir Brian Hoskins, was very frank about the shortcoming in climate science. None of this would be possible in the USA. And it goes a long way to explain why Mann devotes time to this topic.
One of my complaints of his previous book was that Mann blithely ignored any criticisms of his work. In this book he tackles some of them – even if not always head on. One example was the use of the word ‘censored’. When the data used for his original millennial temperature reconstruction was released it contained a folder called ‘censored’. This was regarded by anthropogenic global warming antagonists as proof of malfeasance; in reality it is a normal statistical term used to define a data sub-set excluded to test its importance to the overall conclusion. Another area he deals with is what he refers to as the ‘divergence problem’. This is the fact from about 1960 onwards most tree rings fail to respond to global warming. In the case of his own work he simply says that his data sets ended in the 1970s and 1980s and claims that the idea of adding the observed temperature for recent years to bring the data up to date, and increasing the hockey stick appearance, was suggested by a reviewer. Elsewhere he deals with a “high-elevation site in western United States”, without actually calling them ‘bristle cone pines’, and accepts that their growth rates could have been influenced by CO2 enhancement rather than temperature increases. This had been a criticism of his record. Another criticism of his work had been that one of the proxy records, sediments from a Lake in Finland, had not only been corrupted by upstream engineering works but had been used ‘upside down’. In one of comments on this Mann says “one of our methods didn’t assume orientation, while the other used an objective procedure for determining it”. This appears to be an admission that the orientation might not have been correct though elsewhere he says that this record did not change the overall conclusions.
So, if other climate scientists might have understood the oblique references in the book how might the public react to the book. Well of course few of them would have picked up the allusions and would quite possibly have been unaware of the significance of some of the statements. Another objection of proxy records is that, for statistical reasons, they underestimate the variability of the parameter they are estimating. Mann recognises this and explains this is a reason for the wide error bands. It is quite possible that increases in temperature such as those from 1910 to 1945 or 1975 to 2005 might have occurred in the past but not have registered in the proxy record. Again few members of the public reading this book would have understood the point and simply seen the ‘blade’ of hockey stick and not realised that the handle could have been as curvy as the blade. Another example of misleading the public is the graph he presents of a projection of temperature made in 1988 but he only includes data “available through 2005 in this analysis” even though later data were available at the time of writing the book and show the projection as been less accurate.
Elsewhere I have argued that there was need for a book in a popular style to combat the popular books of AGW antagonists – this is indeed such a book. What is now needed is a book which arbitrates between two sides.
Author: Michael E. Mann
Publisher: Columbia University Press, 2012
MICHAEL MANN AND LEE KUMP: DIRE PREDICTIONS – UNDERSTANDING GLOBAL WARMING
The Reader’s Digest magazine used to publish what they referred to as “unexpurgated abridgements.” By this they meant that they had left in the exiting bits and cut out the boring bits. This book could be considered an “unexpurgated abridgement” of the IPCC 2004 Technical Assessment Report. A lot of the detailed science has been left out but the elevated temperatures and other symptoms associated with an attack of ‘dire era’ are given lurid prominence.
The book does give a clear and approachable synopsis of how our climate operates and how human activity can lead to changes. As an introduction to the science, the book is quite good. It is clearly written and has good supporting material. It also tackles some of the issues raised by sceptics.
In a recent double interview in Discover magazine with Judith Curry and Michael Mann, Judith Curry drew a nice distinction between ‘political sceptics’, who do not want climate change to be true, and ‘scientific sceptics’, whose opinions are based on the evidence. I would suggest that there is a third type of sceptic: the ‘bar-room’ sceptic, who’s not reticent about sharing his knowledge over the internet. You know the type “Why does the IPCC ignore the book ‘The incredible lightness of being’ by the Russian Milan Kovich which proves CATEGORICALLY that the recent so-called warming has all been due to fluctuations in the earth’s orbit?” Unfortunately the authors tend to engage with this level of sceptic rather than the scientific sceptics. The issues where there is real scientific debate, the ‘hockey-stick’ and the urban heat island effect are either ignored or glossed over. Instead they rebut claims that the increase in CO2 is due to natural fluctuations, which scientific sceptics generally accept, or raise the hoary chestnut of “In the 70s the scientists said we were in for global cooling so why should we believe them now?”
The way they tackle the cooling/warming issue says a lot about the authors’ scientific credibility. They present a pair of graphs (page 45 in my edition) which show that the northern hemisphere temperature fell from 1940 to 1970, which explained the then current belief in cooling, and then again increased. Like the rest of their graphs there is no reference to the source but as it starts in 1850, and only the CRU record started in that year, it is reasonable to assume that that was the source. Yet their graph is very different to the CRU one: they show temperatures rising from 1970 to the present by 1.8 °C but the CRU data shows a rise of less than half of that. Elsewhere (pages 20 and 88 in my edition) they show graphs of ‘past observed surface temperature changes’ with an almost constant rate of temperature rise and no sign of the 1940 to 1970 fall. This is very different to the above graph. Since the observed global temperature record shows similar variation to the northern hemisphere record that does not explain the anomaly. Once again without references it is difficult to be definitive but it is almost certainly the ‘modelled’ temperature increase which they have presented as ‘observed’. This gives the false impression that the temperature increases projected by the models follow on naturally from steadily rising observed temperatures.
The book is in fact heavy on dire predictions, based on model projections, but very light on evidence that the models were able to represent past changes accurately. For example, they talk of precipitation changes as being probably of ‘more importance than temperature changes’ but present not a shred of evidence of how well models simulated precipitation. At least the IPCC report does have a shred of evidence: a graph which occupies 1/8 of a page!
What is most frustrating is the fact that this biased, one-sided, presentation of the facts is counter-productive. I fully accept that people are in part responsible for the recent temperature increase. I fully accept that there are many reasons, one of which is CO2 emissions, for reducing fossil fuel consumption. I fully accept that climate projections should play a major role in how we plan for the future. Yet, largely because the IPCC and scientists chose to ignore Abraham Lincoln’s dictum and think that in this ‘information age’ they can ‘fool all of the people all of the time’, the number of climate change sceptics is currently growing.
To give a final example: in his book “Cool It” Bjorn Lomborg mentions the 35,000 people killed in a heat wave in Europe. He also mentions that many more people die of cold in winter and follows it with a nuanced discussion of age profiles and the difficult moral question of how you balance the deaths of old people and of children. In this book only the heat deaths are mentioned. If you are an intelligent, thoughtful, person which approach is most likely to help form your opinion?
I also noticed a typo on the back cover where the book is described as being a scientifically ‘based’ overview. And where, you might ask, is the typo? It’s the missing “i” of course?
Authors: Michael Mann and Lee Kump
Publisher: Dorling Kindersley, 2008