This is not a serious implementation document, rather it is intended to point out problems and a possible direction for solution.
With the notable exceptions of George W. Bush and the Russian government, most learned people agree that we've screwed up the environment pretty good. And that in the near term, things are only going to get worse.
While there are lots of people, especially less developed tribes of aboriginals, around the world who fit into nature quite easily, nobody really does things in a way to minimise impact. Do we pick the sapling that is growing in a bad place, if we need a sapling? At some level, we all show disregard for nature being full of living things.
What really separates "modern" civilisation from these people who fit into nature is numbers (or volume). One person walking across a meadow of grass in hiking boots, leaves no lasting impression. Hundreds of people walking across the same part of a lawn will kill it quickly. Most of the people don't intend to kill the grass, they just don't think. It saves them 37 seconds getting from point A to point B, so they do it.
Some ecosystems are very fragile. There are places in the arctic, where tire tracks from a vehicle travelling across the land only once, can be seen for years (or decades).
I've never gone looking for any papers on pollution or environmental effects of civilisation in the ancient world, but they would be interesting. I suspect early man did little or nothing to minimise the impact of larger civilisation centers had on the environment.
But back then, or even before, mankinds effects on the environment were mostly of a local nature. Probably the longest lasting of the non-local effects would be water pollution of moving bodies of water. We just don't have a history of thinking responsibly about the environment.
Even if you look at various aspects of "bush craft", the kinds of activities done by people who live in the "bush" and are in tune with it, they are seldom designed to minimise environmental impact. It is mostly the small scale of the activities which minimises their impact.
Today, our population and technology are high enough, that it really isn't difficult for us to have a lasting local or global impact on just about any aspect of the environment.
I couldn't hope to hit upon every area of concern, or come up with all possible solutions. This hopefully catches a few areas that most people have some knowledge or feeling about, and perhaps we can expand from there.
I'm not trying to pick on fishermen, but they are first in this writeup. I really don't think we can afford to keep fishermen around, not in anything like their current arrangement. This is as a whole, not every fisherman.
We have been driving species to the point of extinction or even making them extinct, and many (most?) fishermen don't see the problem. How about we go about things differently.
Let's say someone has decided that people like to eat cod. From our harvesting of cod from the ocean, we have some idea as to how big the market is. Okay, this person now has to find a way to grow cod for that market, with no access to the ocean. He can't put a pen in the ocean. He can dig a hole in the ground, and put in a pool. He can put in above ground tanks. He gets rainwater to fill his water containers with (not "city" water, and not ground water). He can get salt to make the water saline. This person is going to have to know an awful lot about cod in order to grow them himself. And he could easily end up needing other species, which he would have to grow as well, just to grow cod.
With no contact between these farmed fish, and the ocean, it is unlikely that diseases can move between them. We also are unlikely to be threatening species with extinction under this kind of scenario.
So, pick your species: cod, salmon, shrimp, clams, trout, .... If you understand the lifecycle and ecosystem, you should be able to farm fish. Safely. It's safe for the consumers, as there shouldn't be pollution/contamination concerns. It's safe for the ecology, as there is no contact between the artificial "ocean" and the real one.
And if you are one of those people who like to eat whale meat, good luck building an artificial habitat big enough to farm whales. Leave the wild, for the wild.
Some people like hunting and fishing. Well, if someone wants to operate a property where they farm deer, bear, trout, or whatever, they should certainly be allowed to let people come in there to shoot a land animal or catch a fish with a hook. As far as going hunting and fishing in the wild goes, there are too many people having too much impact in the back country as it is. The easiest solution is just stop it for all. Let the wild go back to regulating itself. If it can.
Just like with fishing, the environment must be self-sustaining and isolated. No barbed wire fences, you are probably looking at solid walls at least 20 feet tall (for deer). You want a stream on the property? Well, if you want to landscape the property so that water flows, and you put in the pumping to recirculate the water that is flowing, sure.
A question here more so than for fish above, is how much potential for transmission of disease is airborne? Insects and birds will allow for some communication of disease and pest vectors with the outside world.
Grain farming is another place where we can get disease and famine because we tend to set up monocultures. Farmer Jones grows wheat, as do all of his neighbours. Then a disease moves in, and everyone gets wiped out. It's hard to force people to not grow what they want to. Crop insurance is probably the place to try things. The premiums you pay depend on the distance between your field of some kind of crop, and the nearest field of a crop which has the same kind of disease or pest problems. If farmers purchase crop insurance, it gives them incentive to diversify. I'm not sure how one goes about helping provide incentive to better use fertilizer, conserve soil, and other aspects of modern dryland grain farming.
Livestock farming has similar problems with disease. I would expect a similar approach would work. Question though, is there such a thing as insurance for livestock? Some ranchers raise calves for themselves, some raise cattle from calves, some raise cattle to sell calves. Since the lifecycle has at least one break in it, at which point transport can happen, disease and pests are more mobile.
Do we have enough technology to make an impact on livestock? RFID tagging is starting to be used. We could put mass and thermal sensors in single animal gates, and with the serial number in the RFID tag, obtain measurements of animal weights and body temperatures on a regular basis. Building gates between pastures, or on transport trailers, that incorporate this sort of technology is more expensive than what's in use now, and significantly different. It also requires a lot more in the way of data storage and analysis. Does it pay off in term of healthier animals and improved productivity? Do we need to add other sensors?
As with the sports hunting and fishing, if the rancher wants water features on the land, they can put in the pumps to recycle water. With the high fertilizer/organic component to manure, I would imagine that all land boundaries be set up to eliminate any component of uncontrolled release of nutrients via runoff.
Many tracts of otherwise wild or public lands are often used for cattle. One name for this is community pasture. This kind of land usage is incompatible with leaving the wild for the wild.
Concern about fossil fuel usage can involve some similar thoughts. It's obvious that we have become accustomed to using liquid, high energy density, fuels which can be oxidised with air to drive motor vehicles. If the only thing fossil fuels were good for, was burning, there is less wrong with using them for fuels. However, that isn't the case. Fossil fuels are valuable as feedstocks for many kinds of chemicals, plastics and pharmaceuticals.
Coming up with an alternative fuel with a similar energy density is difficult, finding one with a better performance with respect to pollution and greenhouse gas emissions is the offsetting factor to decreased energy density.
The time to find this new fuel, whatever it is, is now. We have to have a replacement in place before the arctic warms up enough that transport across the arctic by supertankers is feasible. We cannot afford anything remotely like an Exxon Valdez disaster in arctic waters. Moving freight across the arctic is fine, moving crude oil across the arctic is out of the question.