There's an interesting piece in Slate, The Great Schism in the Environmental Movement, which seems to be a distillation of trends which have been bubbling within the modern environmentalist movement for a generation now (I've read earlier manifestos in a similar vein). I can't assess the magnitude of the shift, but here's the top-line:
But that is a false construct that scientists and scholars have been demolishing the past few decades. Besides, there's a growing scientific consensus that the contemporary human footprint—our cities, suburban sprawl, dams, agriculture, greenhouse gases, etc.—has so massively transformed the planet as to usher in a new geological epoch. It’s called the Anthropocene. Modernist greens don't dispute the ecological tumult associated with the Anthropocene. But this is the world as it is, they say, so we might as well reconcile the needs of people with the needs of nature. To this end, Kareiva advises conservationists to craft "a new vision of a planet in which nature—forests, wetlands, diverse species, and other ancient ecosystems—exists amid a wide variety of modern, human landscapes."
Let's take this debate as a given. It is fundamentally normative. That is, it is about values. We we need to tread carefully before projecting values across disputants. Far too often in this domain people seem to presume normative alignments, and therefore confuse ideological disagreement for rejection of factual truths. But, one thing to consider is that it is probable that human beings have already radically reshaped the ecological character of the world over the past 100,000 years. The implicit model that many older environmental activists seem to present is a framework pitting man & the machine vs. nature (the Shire vs. Mordor). But it is just not a useful dichotomy for many. It is possible that there was, and is, no "pristine" nature. These disparate perspectives come to the fore in particular in post-colonial landscapes settled by Europeans. There is a long tradition in these areas of transforming 'natives' into 'Noble Savages,' who have attained some idealized harmony with Nature. The reality is that it is not harmony that was attained, but equilibrium. The arrival of anatomically modern humans to Australia and the New World resulted in a 'shock' to the ecological system, as megafauna went extinct due to the new variable of human predation. Even if H. sapiens were not the sufficient condition for these extinctions (populations naturally go through cycles), it is likely they were necessary (i.e., humans might extirpate species during times of low census size). But it is not just the initial impact in terms of species turnover. Australian and Amerindian populations seem to have reshaped the long term character of the landscape through fire. Charles C. Mann argues in 1491 that the vast forests which colonial and early American settlers cleared were in fact second growth, which emerged in the wake of massive die-offs of indigenous peoples due to Old World disease. All of this is fundamentally complicated. Instead of a decision tree with two options, 'Civilization' vs. 'Nature,' there is actually a space populated with a multitude of positions. As someone touched by a moderate amount of biophilia my vision for the future is one of arcology based urbanism, massively scaled up algaculture, and megafaunal rewilding through genetic engineering and ancient DNA. Rather than idealize a mythic past we should endeavor to forge a new future. So it was, and so shall it ever be.