Dorling does not seem overly concerned to explain or provide evidence for the positions he adopts in Population 10 Billion. We learn a great deal about how he views the world, when he was born, how he dislikes SUVs and so forth, but we don't get closely reasoned arguments about population and resource usage. Most of Dorling's projections are of his own views and not of demographic data, which is infuriating given his skills as a quantitative geographer.

Of even greater concern is his breezy willingness simply to ignore evidence or travesty it in his sheer pleasure at the flow of his writing. Take Malthus, for example. Dorling styles Malthus's advocacy of family limitation as resulting from "the sexual hang-ups of an economist of the cloth". Malthus (as I presume Dorling knows) was in fact a happily married father of three with no recorded sexual hang-ups. He advocated smaller families as a way to alleviate the lot of the poor, an aspiration Dorling would clearly endorse. Surely it behoves a book aimed at the general public to explain the arguments it wants to rebut properly and then respond to them patiently? To do otherwise is to demean that public's intelligence, to assume it does not want to or is not able to follow the detail of the argument. As a historian myself, I am left worried by such authorial legerdemain: how can one trust someone's projections for humanity's future if they do not attend to demonstrable facts about its past?

Similar strictures apply to Stephen Emmott. He has a swathe of academic credentials and runs the Microsoft Lab in Cambridge. Ten Billion emerges from a stage show performed in London in 2012 and betrays its "occasional" origins in that its format is akin to a Powerpoint presentation. 

Emmott's stance is the reverse of Dorling's, suggesting that the resource usage of ten billion people will lead us beyond tipping points in the earth's climatic system and thereby to societal breakdown. He is also clear that we can already see tokens of that collapse today. In framing himself as a scientist and predicting disaster, Emmott falls squarely into the lineage of population jeremiahs from Paul Ehrlich onwards, both the tone and the pamphlet style of Ten Billion echoing The Population Bomb from half a century ago. 

Alas, the comparison with Ehrlich does not end there, for Emmott shares with Ehrlich a certain laziness in argumentation, papered over by his appeal to his scientific pedigree. For example, Emmott conflates the fact that 87 per cent of the world's fisheries are now "fully exploited" with the idea that they are "exhausted". This is simply not true; a fully exploited fishery is one which is being harvested at its sustainable maximum, not one which is exhausted. Examples could be multiplied, but each would lead to the same point: Emmott's case for us to pause for thought would be stronger without such basic errors. Such exaggerations dent his credibility as assuredly as Dorling's short-cuts undermine his claims to our confidence.