This article compares chronologies reconstructed from historical records of prices, wages, grain harvests, and population with corresponding chronologies of growing conditions and climatic variations derived from dendrochronology and Greenland ice-cores. It demonstrates that in pre-industrial, and especially late medieval, England, short-term environmental shocks and more enduring shifts in environmental conditions (sometimes acting in concert with biological agencies) exercised a powerful influence upon the balance struck between population and available resources via their effects upon the reproduction, health and life expectancy of humans, crops, and livestock. Prevailing socio-economic conditions and institutions, in turn, shaped society's susceptibility to these environmental shocks and shifts.B raudel opened his great trilogy, Civilisation and capitalism, 15th-18th century, by likening the rhythm of population change over the pre-industrial centuries to a series of tides, whose 'alternate demographic ebb and flow . . . make almost everything else seem secondary'. 2 The marine analogy is powerful but paradoxical: the causes of oceanic tides are so well understood that their ebb and flow may be predicted with precision, whereas the mechanisms responsible for these human tides remain enigmatic. Even counting, measuring, and dating the latter can be a considerable challenge given the difficulty of observing population trends before the advent of explicit demographic evidence in the sixteenth and seventeenth centuries. For earlier periods Braudel's 'alternate demographic ebb and flow' can usually only be inferred from an array of 1 This lecture is dedicated to the memory of two distinguished medievalists who both died in 2007, their work incomplete: Professor Larry Epstein and Professor Harold Fox. I am grateful to Professor Richard Smith for the invitation to give it. The final version of the lecture was written during a period of research leave spent at the Malcomson cast an expert eye over the text and provided advice and encouragement at a critical stage. Three referees and the editors offered suggestions which proved helpful in translating the text from the medium of a lecture into that of an article. Finally, particular thanks are due to Mike Baillie, Professor Emeritus of Palaeoecology, The Queen's University of Belfast, for many stimulating conversations and for providing data and advice on dendrochronology. He nevertheless bears no responsibility for the views expressed in the following pages.2 Braudel, Civilization and capitalism, p. 31.