The implicit belief in the title says it all. We think “the planet” belongs to us, and is ours to “give back” to nature. Our real and primary work is to turn that mistaken belief around, not just in talk but in how we actually live.

Doing that will necessarily generate far more “impact” on our dominant cultures than anything imagined in the half-earth proposal.

And, it will happen whether we want it to or not, as several other responses have pointed out.