David Keys is archaeology correspondent for the London daily paper, The Independent, as well as a writer on historical climate change, and contributor to television programs on archeological subjects. His book Catastrophe: An Investigation into the Origins of the Modern World on a 6th AD climatic disaster has had a mixed reception - he and his theory were featured in the 2000 Television pilot to the PBS series, Secrets of the Dead
Keys' book Catastrophe: An Investigation into the Origins of the Modern World theorizes that a natural disaster caused changes during the 6th and 7th centuries in the Christian world that included the end of ancient civilization and initiated what is now known as the medieval era. Key's work expands on that by Mike Baillie in Exodus to Arthur : catastrophic encounters with comets in which the primary evidence for the event is dendochronology, as well as acidity in Greenlandic ice cores, as well as accounts of historians such as John of Ephesus, Procopius, and Cassiodorus on changes in climate, including dimming of the sun. Keys adds further information from East Asia and develops his own version of the theory; he attributes the changes to a volcanic event in East Asia, in 535 AD, possible at Krakatoa. The work has received mixed reviews: Publishers Weekly criticized the book, writing that "Huge claims call for big proof, yet Keys reassembles history to fit his thesis, relentlessly overworking its explanatory power in a manner reminiscent of Velikovsky's theory that a comet collided with the earth in 1500 B.C." A mainly critical review in The New York Times Book Review by Malcolm W. Browne concluded that "Still, this book must be taken seriously, if only as a reminder that survival in a world threatened by real dangers hangs by a very slender thread". British archaeologist Ken Dark commented that "much of the apparent evidence presented in the book is highly debatable, based on poor sources or simply incorrect. Nonetheless, both the global scope and the emphasis on the 6th century AD as a time of wide-ranging change are notable, and the book contains some obscure information which will be new to many. However, it fails to demonstrate its central thesis and does not offer a convincing explanation for the many changes discussed". Archaeologist Brian M. Fagan referred to it as "investigative journalism" and "an interesting and, at times, compelling narrative " concluding that "Keys is right to draw attention to the importance of short-term climatic change, but, in our present state of knowledge, the deterministic and somewhat sensationally written Catastrophe goes too far."
