When did people change the physical environment?

Answer 1

People have been changing their natural environment since there have been people - which is to say about 200,000 years ago, according to our best guesses.

People aren't the only species that has changed the physical environment. The great barrier reef was constructed by coral.

Change to the physical environment is neither beneficial nor detrimental. The earth constantly changes. A thousand years ago, Leif Ericsson founded dairy farming communities in Greenland. They were abandoned a couple of centuries later as the climate grew colder there. They used to have vast vineyards in Great Britain, supposedly producing really fine wines, but then the climate changed, and the vineyards were not very productive.

And Native Americans have oral traditions, and there are paintings, of Amerinds hunting down a wooly mammoth - sorta like an elephant with hair all over its body. Nobody can explain it.

With "global warming" we are supposed to have rising sea levels, but along the Alaskan shoreline, the sea levels have been dropping.

It may well be that we're experiencing "global warming" but that is relatively easy to accomplish. We probably have more to fear from the rising CO2 levels in the air; there are no studies that show the long-term effects of mammals living in a high CO2 atmosphere. We probably ought to encourage development of space travel and self-sustaining colonies in the asteroids and on the moon, for at this point, it's as if we're on an ocean liner without any lifeboats.