You can't 'save' the Earth.
At least not in the sense that it should be preserved in its current state - the status quo.
That's what 'saving' something is. When we talk about saving the Earth, what we mean is that we should stop changing it - we should preserve it. OK - so is the current condition the way we want things to stay forever? And does that mean that we need to stop consuming - everyone in the world? Because that is the only way that things are going to be preserved in their current state.
Or do we mean that only certain things should be preserved? Things like wildlife, and habitats.
Well, that covers everything. Find some place which is not habitat to some life form and you win the nobel prize - life is EVERYWHERE you might care to look for it. How does one make a case that some species and habitats warrant protection and others do not?
Many go so far as to say we should restore the Earth.
To what condition, I ask? And what time period do we conclude makes a good target for which we should aim? 100 years ago? Probably not. 500 years ago? Why would that be better? 10,000 years ago? Is that being ridiculous? I don't think so.
And to which geologic time period should restoration proceed? Where does one draw a logical line? There is no logical differernce between 100 years and 100 million years.
One can not say that things are different now because humans have caused extinctions and losses of habitats. We are, quite simply, an ecological dominant speicies - there have been many over time, and all have done the same thing we have. They have outcompeted other species, resulting in irrevocable habitat changes and affecting evolution and Earth history forever into the future.
And where do we draw the line as to what species to restore? Do we continue our genocidal warfare against pathogenic bacteria and viruses, or do we also go after fleas which are the vectors of such pathogens (go ahead - someone make a case that fleas should be protected), or do we go up the ladder and erradicate the rats which carry the fleas (anyone not have an instinct to kill any specimen of ratus vulgaris upon sight)? From a perspective that all species warrant protection and that all of the organisms in that particular vector (bubonic plague) are/were vital components in its propagation, what do we preserve and what do we erradicate in order to preserve ourselves? Ditto malaria - which is now killing people in multitudes because the only effective pesticide for the culex pipiens mosquito was DDT which is now in short supply. We eliminated DDT to save raptors (all well and good) and the end result is many people dying. All well and good?
I don't advocate re-introducing DDT, but use this example that at some point in any attempt to "save" the Earth, there are consequences to human civilization. We can look at many similar examples but that one will suffice for now.
So let's take the approach that we want to preserve all currently undeveloped land and sea areas to pre-human civilization conditions. That implies that there is some primordial condition for each such area that represents the status quo and that is what we strive to recreate and then preserve.
Let's look at a worthy candidate - Yellowstone Park. It's already preserved to some degree. The re-introduction of wolves a couple decades ago stirred up a controversy amongst local ranchers which rages to this day - one re-introduced species. But that's simple. What abuot the geyser field? An earthquake in the 1990s resulted in Old Faithful geyser being not quite so faithful - a re-alignment of the subterranean pluming system has caused a more irregular eruption schedule - and some woman tried to sue the National Park Service because she did not get to see that geyser epupt! I'm not kidding.
So - should we engineer the geyser field to re-establish conditions to the pre-1990s? Install some pumps so that Old Faithful erupts every 68 minutes again?
Well ... I don't need to get ridiculous, but we could continue this line of argumentation all the way back to the time before the Yellowstone caldera formed and make a good case that any of the many conditions going back in time are just as worth re-establishing as any other.
Regardless of humans' presence or absence, the Earth changes - it is the only constant of Earth history - CHANGE.
We do not live in a special time. We do not live in a priviledged environment. The Earth has not always been as it is now. The Earth from 50 million years ago (m.a.) would be unrecognizable to us, and the Earth at 100 million years ago would be unrecognizable to the inhabitants of 50 m.a. and so on. On a local scale, one does not need to have such an expansive time lapse between interrations and the changes render your own little corner of the world as vastly different than in previous times.
Life on Earth has not only changed the Earth over geologic time, life on Earth has made Earth what it is. The atmosphere of today was manufactured by life. The atmospheric composistion is what dictates the behaviour of weather patterns and climates, which in turn drive erosion, transportation and sedimentation, which in turn create new landscapes and geology, which in turn are eroded by the atmosphere.......
We are part of the web of life. The changes we visit to the surface of the planet are just the latest in the processes of changes which life and the physical planet have been enacting for 4 billion years.
As Bradbury noted "I hate a Roman called 'Status Quo'". Well, in terms of the Earth, there IS no Roman called Status Quo.
Life is not a passive passenger (the roots of those words are related) on spaceship Earth. Life changes Earth - it always has - it always will.
The Earth does not need to be saved, as in rescued, from us any more than it does or did from any other species.
The Earth does not need to be saved, as in preserved - quite simjply, it can not be.
Once again, I don't advocate wasteful living. We are a self-recognizing, forward-looking species, unique in all the kingdoms of life on Earth and that attribute comes with some responsiblities, but that would be moralizing...