The Irish famine, the Black Death of the 14th century and the many plagues that followed it, the famines of the 13th and early 14th century, are well known. There is sketchier historical record of previous plagues and famines in western Europe back to Roman times.
Archaeology shows that a major change in climate badly affected the northern and western parts of the British isles in the Bronze Age - wheat, for example, could no longer be grown - and there appears to have been a severe fall in both population and material culture as a result. We can now only guess at what hunger, disease and warfare resulted from the competition for declining resources.
It is precisely because the environment changes, and can be changed by our human actions, that people espouse environmental causes. By better understanding how we interact with our environment we hope, unlike our ancestors, to be able to avoid the pain that otherwise goes with those changes.
To answer Mr Warnock's question of whether the environment is endangered or just evolving, it depends on your point of view. From that of the bacteria that break down oil-spills, to take just one example, it hasn't looked better for aeons.
Market Rasen, Lincolnshire