Read the text and decide which answer (A, B, C or D) best completes each collocation or fixed phrase.

Whenever we read about the natural world nowadays, it is generally to be giver dire predictions about its (1) ... destruction. Some scientists go so (2) … as to assert that from now on, the world can no longer be called 'natural', insofar as future processes of weather, climate and all the interactions of plant and animal life will no longer carry on in their time-honoured way, unaffected by humans. There will never be such a thing as 'natural weather' again, say such writers, only weather affected by global warming. It is hard to know whether to believe such (3) … of doom, possibly because what they are saying seems too terrible to be true. There are other equally influential scientists who argue that climate, for example, has changed many times over the (4) …, and that what we are experiencing now may simply be part of an endless (5)… of change, rather than a disaster on a global (6) …