That's a pretty big "if." If wishes were horses, beggars would ride. We can only go with the data we have. Indulging "what ifs" about how people might have behaved centuries ago is a fruitless pursuit. Fifteen hundred years ago, the north Atlantic region (at least) was just coming out of a cold spell which is often referred to as a "mini-ice age." Twelve hundred years ago, there was a dramatic warming trend in the north Atlantic region (at least) known as the "little climactic optimum." In the third century BCE, a merchant captain sailing from Masilia (Marseilles) reported that he encountered pack ice just south of the coast of what we now call Iceland. That was during the little ice age. A thousand years later, the Albans (the people who had inhabited Scotland before the Picts and Irish arrived) were hunting walrus off the coast of Iceland, and probably at least "over-wintering" there, it not actually settled there. By the late 800s, the Norse were colonizing Iceland, and although they claimed that they were the first there, they weren't very good propagandists. Their own sagas tell of them enslaving the Irish they found there. (They may have been Irish, they may have been Albans--but people definitely were living in Iceland before the Norse arrived.)
More than a century later, Eirik Raudi (we call him Eric the Red) was outlawed for three years for manslaughter (a euphemism for murder--you have to be careful what you say in a society in which nearly every many goes about heavily armed). In 981 he sailed to Greenland. He spent three years exploring, and then having returned to Iceland, in 985, he lead colonists there. A few years after 1000, the Norse made an unsuccessful attempt to colonize Newfoundland, undoubtedly what Leif Eiriksson had called Vinland. That was the height of the little climactic optimum. In a few centuries, the climate had changed so dramatically that not only were the coasts of Iceland and Greenland free of the pack ice which had previously prevented their colonization, but they could be colonized and support large human and livestock populations.
After 1200, when the little climactic optimum had ended, the climate began to cool rapidly. By 1450 (or thereabouts), a Dutch whaling captain recorded finding the last Greenlander, dead, lying face down on a path leading from an otherwise empty settlement. By 1600, lakes in northern Scotland would be frozen over by the end of August. By 1709, the winters were so severe, that that year in France, birds froze to death and fell dead from the trees, and rabbits and badgers froze to death in their burrows. Wolves stalked the poor around Paris, and attacked the guards at the barriers on the roads leading into the city. When they could get through, they stalked the poor in the streets of the city at night.
Climate change, just in the historical period alone, has been known to change rapidly and dramatically. "Green" policies are probably a good idea in their own right. However, i see no reason to assume that climate change is anthropogenic. We are not nearly as important as we think we are. Hurricanes and typhoons prove that to us on an annual basis.