I’ve finally got round to reading a number of the many climate change-related books that have been published in recent months. These books seem to have caught the public imagination in ways that are different than in the past, and so it’s worth examining how they do. The three I’ve read are; Eugene Linden’s The Winds of Change, Elizabeth Kolbert’s Field Notes from a Catastrophe and Tim Flannery’s The Weather Makers. The first two writers are journalists, while the third is a scientist by background, and while there is some overlap in contents all of them, they are clearly distinct works in quite different styles. I’ll mostly stick to commenting on the science though…
Eugene Linden’s book is very well written and sets up the book as a prosecutorial case that climate change can have (and has had) serious impacts on human society. He picks out a number of purported climate changes – the 8.2 kyr event, two less well-defined changes around 5200 and 4200 years ago, a mysterious (volcanic?) event in 536 AD, the Mayan collapse around 800 AD, and the Norse colony collapse in Greenland to make his case that societies can be vulnerable to abrupt shifts in rainfall, temperature etc. The 8.2 kyr event qualifies as an abrupt change by almost any definition (except that adopted by the NRC panel on the subject curiously) and was most likely tied to the catastrophic final draining of paleo-lake Agassiz and subsequent changes in the North Atlantic ocean circulation (see a summary of some of our recent research on the topic). This mechanism is not relevant to the other highlighted changes, and unfortunately no well supported ’causes’ have yet been demonstrated for the events in 5200 and 4200 BP. Solar forcing has been suggested for the Mayans and for the Little Ice Age, but hard evidence is difficult to come by.
Societal impacts linked to the 8.2kyr event involve potential changes in the Natufian culture in the Levant, but while intriguing, the imprecision of dating and lack of written evidence mean that this link remains speculative. However, evidence for societal impacts are tied to drought on ancient civilisations is much stronger – the ancient ‘Curse of Akkad’ describing the droughts affecting the Akkadian Empire; the Mayan collapse etc. – and this is well brought out in the text.
One example that I wasn’t previously aware of, were the climate events of 536 AD – ‘dry fogs’, crop failures, ‘dim suns’ and yellow snow etc. – features consistent with a large volcanic eruption, possibly near the site of Krakatoa – and which correlates with evidence of a sulphate peak in the North GRIP ice core at the same time. Linden quotes David Keyes as suggesting that the societal impacts of this event included the plague and the onset of the European ‘Dark Ages’. You don’t necessarily need to buy into this to get a sense of how disruptive this event was though.
Linden talks to the right people and makes a strong case, but I think he errs in seeing all of the climate changes as being analogous. The effects of circulation change in the North Atlantic are different to (potentially solar-driven) rainfall variability in the sub-tropics and are different again from the impacts of changing frequency and intensity in El Nino patterns. He unfortunately makes a large over-estimate in describing the magnitude of the 8.2 kyr event (claiming it lead to 5 deg C of global cooling, instead of a local result for Greenland), and then compares other ‘events’ to this more (climatically) well-documented case. There are a few more minor errors – isotopes are denoted by a pre-subscript (18O) instead of a superscript (18O) but we can probably blame the copy-editor for that. Linden appears to take seriously a suggestion that the Mayans were aware of multi-decadal variations in the sun’s irradiance and built them into their calendar – something that seems extremely unlikely to me. Overall though, the evidence for serious climatic impacts on societies is pretty strong and he swayed this member of the jury.
Next up is Elizabeth Kolbert’s book based on her extremely readable three-part series in the New Yorker last year. (I should note that I talked quite extensively to Elizabeth when she was doing the research, so I may be a bit biased). The benefit of having the famously pedantic New Yorker fact checking department (Hi Louisa!) working on your behalf is very clear as I wasn’t able to find a single mis-statement on the science. There is some overlap in material with Linden’s book – for instance both authors spend some time with Harvey Weiss talking about drought and the Akkadians. But Kolbert’s book is much more closely tied to the scientists and the environments in which they work than Linden’s, and as such, is a more personable and well rounded portrait of how the science is being done and why the scientists have come to the conclusions they have.
Kolbert spends time in the field in the Arctic, in Greenland, in the smoke-free rooms at the UN, in the dark corridors of a climate modelling centre and even includes a few lines of Fortran code from the GISS climate model – gobbledygook possibly even to the scientists that wrote it! But it’s an indication that she spent the time down in the trenches and that’s pretty impressive.
Finally, Tim Flannery. His book appears to have made the most noise and Flannery himself has generated a lot of media attention (and controversy) on his book tours. As befitting a book by a scientist, this one has by far the most ‘content’ of the three, and unsurprisingly, is a tougher (though still accessible) read. The sheer speed at which different studies and subjects are covered make it difficult to get into anything in depth. In itself, that isn’t bad – there is a lot of ground to cover – but it does mean that subtleties and caveats get lost.
As a scientist, one of the things I look for in popular science accounts is an appropriate recognition of the difference between a suggestion made in a single paper and the description of any ‘consensus’ on the issues (such as described in the IPCC reports for instance). We have made the point repeatedly here that single papers need to be placed in context and don’t necessarily overturn previous work. In the three books discussed here, I have the impression that Kolbert most recognises this, but unfortunately that recognition is not at all obvious in Flannery’s text.
In case after case, Flannery quotes a single paper as an absolute proof of the particular contention. One example taken at random, is in relation to the MSU satellite record (which we’ve discussed here before, so skip this next section if you’ve heard it all already). Flannery raises the issue of the at-one-time apparent contradiction between the satellite records (usually taken to be MSU 2LT from the UAH group) and the surface temperature records. He quotes the Fu et al paper (which discussed the stratospheric contribution to MSU 2) as providing the final word on the subject. Now while this contribution was useful (and fitted nicely with previous work), it did not reconcile the different records. That had to wait until August last year when errors in the UAH algorithm were brought to light, and for a re-analysis by RSS demonstrating the sensitivity of the results to methodological issues in the treatment of the raw data. Obviously, one cannot fault Flannery for not knowing ahead of time what would be discovered, but he can be faulted for assuming that the one paper he quotes ‘solved’ the problem. Flannery is quite critical of the IPCC process, describing it as ‘lowest common denominator science’ and claiming that it must be assumed that things are likely to be worse than are described in those reports. I think he is fundamentally mistaken on this point and his too-frequent absolutist statements based on preliminary science are a classic example of why ‘consensus’ reports are both more careful and more correct than an individual opinion. For instance, there is no way that a ‘consensus’ statement that climate sensitivity is probably around 3ºC (plus or minus a degree) should be interpreted as implying that climate sensitivity is more like 6ºC. In science, ‘conservatism’ implies proper acknowledgment of the uncertainties, it does not imply that systematic underestimation of effects.
There are also a number of careless errors in Flannery’s book that frequently deduct from his main points. How many interglacials before our own was the one 430,000 years ago? Five according to the Flannery (p68), four according to everyone else. How much flow in the Amazon? 1 Sv (106 m3/s) in the book (p192), a fifth of that in the real world. Has the Gulf Stream ‘stopped’ three times in the Holocene? No. Does global dimming indicate that we will be required to take CO2 out of the atmosphere in order to stabilize Earth’s climate? (p302). No. And there are more…
All of the authors end by emphasising the concern most scientists in this field feel for the ongoing climate changes and the potential for future serious impacts. Flannery is actually good on this point and discusses a number of the options for reducing emissions, some of which are likely only to make the practitioners feel good, some of which may actually do some good. But in terms of which books make a better case that climate change should be taken seriously as a problem, Kolbert’s and Linden’s are the more persuasive. Flannery’s is too polemical to appeal to those not already convinced. This is a shame, because contrary to Bill Bryson’s endorsement of the book ‘It would be hard to imagine a better or more important book’, I can easily imagine a better one. A rewrite using a lot more ‘suggest’s, ‘may’s and ‘possibly’s would go a long way to making the text more scientifically defensible.
And so, if you are looking for some informative and easy (though troubling) reading this summer, I would highly recommend Kolbert’s book (closely followed by Linden’s). Good reading!