In a way, it’s a nice idea, but there is no way to accomplish this. You cannot really set aside half of the globe or a quarter of the globe or a tenth of the globe and “protect” it. What happens to the rest of the globe will influence it.
If one wants an easy example, look to the national parks in the California Sierra Nevada, eaten considerably through by beetles because of the rising temperatures, and ready to fuel the next fires. And when the pines are off the slopes, the soil and water will run down, and the droughts will intensify as bare dry land spreads.
At least that’s how it’s happened before.
No. What is necessary is not to divide humans from nature, but to draw human sustenance from natural systems and make decisions that protect those systems. Humans are creatures, too, and in the end receive support from ecological systems.
Economic systems only exist to distort distribution between persons.
Start gardening what’s close. Stop eating what’s flown in. Park the car. Devise passive heating or cooling. Trap your rainfall and drink it, and let what’s used flow to your plants. There’s a whole lot of details and a world of small changes, but it’s all a good deal of fun. It takes some learning, but it responds pretty well to insight and learning, too.
And develop your connections and get ready to face down companies and politicians; there’s sure to be some conflict in all this.