It took 3.6 billion years for multi-celled life to appear on Earth, and another 535 million before humans appeared. Since then, our evolution- and survival- have been determined by the environment in which we lived.
That environment has changed over geological time. Now, as then, our survival depends upon our environment- but we have been changing that environment in only lifetimes. It took 4.2 billion years for our numbers to reach 1 billion- but we now add the same number every 12-14 years. And the planetary resources which each of us consumes has risen many fold more. The resulting crisis is no longer one for ‘our grandchildren’. The survival of ourselves and of our own civilisation are threatened.