Crocodiles

Wallace-Wells, in the book at reference 1 which was noticed at reference 2, tells a good story, albeit a rather repetitive one, a story which includes lots of striking but rather sweeping observations. With it striking me that some of them might be generally rather than literally true, so I try to check some of them.

So having told us about the steady move east of the north-south wheat line running down the middle of north America, separating the ranges to the west from the farms to the east, he told us about the steady move south of the southern border of the Sahara desert, at the expense of the Sahel. Thus largely accounting for the troubles in that part of the world. And including the curious fact that the desert has expanded by 10% - but by as much as 18% in the winter (page 52 of my copy). And these Saharan observations I thought to check, which led me to reference 3.

A paper about the changes in the Sahara over the past 6,000 years, in particular its transition from a reasonably wet place then to a very dry place now. One is not blinded with science and statistics and there are good diagrams, but still not an easy read for the amateur and there are lots of long words. I can say that the story looks to have been built on sediment cores - with all their organic detritus - taken from the bottom of Lake Yoa, which lake has been around for a very long time and is accessibly introduced by Wikipedia at reference 6. I think there is controversy about the speed of the change: was it slow and steady over thousands of years, or did the world flip, say over a couple of hundred years, from one state to another - with the answer to this controversy possibly being suggestive in our own predicament.

Then this morning, I remembered that I had a more accessible book about the Sahara, which involved stories of crocodiles surviving in odd water holes, left over from the good old days. It turns out that I do still have such a book, reference 4, left over from the various culls over the years. A book which was once the property of Croydon Public Libraries and has not been stamped either WITHDRAWN or DISCARDED in either black or red. For which see reference 5. Nor can I find a price, despite the fact I am more or less certain I picked the thing up, many years ago, in a second hand bookshop.

Checking, I was pleased to find that there was such a crocodile, reported up by Jean Tilho, a French colonial geographer and explorer, 1875-1956. First appearances respectable enough, so perhaps the story is true. So perhaps I will now reread this book, rather than pressing on with reference 3.

I also notice the pull out map at the map, snapped above, which one can consult while keeping one's place in the text. A courtesy that books of today rarely extend to.

None of which contradicts the Wallace-Wells statement about the creeping forward of the desert, but which is suggestive of a reasonably complicated story and one wonders whether he has bothered to check it himself. Whether his simple, striking statement is a fair, reasonable and appropriate summary of the facts as presently known? Does he employ a squad of reliable research assistants to check this sort of stuff for him?

Reference 1: The uninhabitable earth: a story of the future – David Wallace-Wells – 2019.

Reference 2: http://psmv4.blogspot.com/2019/07/advertisement.html.

Reference 3: Climate-Driven Ecosystem Succession in the Sahara: The Past 6000 Years - S. Kröpelin, D. Verschuren, A.-M. Lézine, H. Eggermont, C. Cocquyt, P. Francus, J.-P. Cazet, M. Fagot, B. Rumes, J. M. Russell, F. Darius, D. J. Conley, M. Schuster, H. von Suchodoletz, D. R. Engstrom – 2008.

Reference 4: Sahara: the great desert – E. F. Gautier – translation by Dorothy Ford Mayhew – forward by Douglas Johnson – 1935.

Reference 5: http://psmv4.blogspot.com/2019/08/darwin.html. Discarded.

Reference 6: https://en.wikipedia.org/wiki/Lake_Yoa.