One of Dr Weiss's former students, Sarah Parcak, of Cambridge University, presented data to the meeting on how a third period of cooling and drying, 4, 200 years ago, destroyed the Old Kingdom of Egypt.

ECONOMIST: Climate change and civilisation

Of course, rain-fed agriculture is even more vulnerable to climate change than the irrigated variety, as Ms Parcak's Cambridge colleague Lauren Ristvet showed the conference with her study of northern Syria during the same period as the fall of Egypt's Old Kingdom.

ECONOMIST: Climate change and civilisation

The dealer trusted him enough to produce a crate of what he said were artefacts more than 3, 000 years old, from Middle Kingdom Egypt.

BBC: Egypt revolution brings golden age for tomb raiders