We all know that climate change is a problem. We know it is caused in large part by greenhouse gasses like carbon dioxide being released into the atmosphere and trapping heat. If we can’t find a solution to global warming, we’re in all sorts of trouble. That solution will involve cutting carbon dioxide emissions. So far, most of us are in agreement. But the discussion tends to end at, “we should really do something.” But what? Even breathing emits CO₂, so we can’t cut our emissions entirely. What is enough? Having an understandable goal—even a politically unrealistic one can give us something to strive toward rather than something to fight against.

That goal becomes obvious once we think about what is happening. Remember that seventh grade science lesson about how the atmosphere changed as soon as plants appeared? Plants would absorb CO₂ and give off O₂. That extra carbon molecule became part of the plants. The plants died. Many of them turned into coal and other fossil fuels. Others turned into more plants. Gradually the atmosphere changed and we got animals, which ate the plants, and emitted more CO₂—but the animals could only emit as much CO₂ as the plants had fixed. Gradually the atmospheric composition changed as more and more of the carbon was locked in giant forests or buried as fossil fuels.

Enter humanity. We start burning the fossil fuels then cutting down and burning the forests. We’re undoing those millions of years of atmospheric shift that make animal life possible.

Thus, the solution is relatively simple. Don’t burn anything over fifty years old. This means no fossil fuels and no burning old growth forests. From an emissions stand point, ethanol is okay because whatever you make it from fixed as much CO₂ as burning the ethanol will emit. Biodiesel is also okay. You can have all the cows you want—so long as you don’t feed them petroleum products. (You’d think that would go without saying—but we feed some weird stuff to our livestock.) And if you really need to burn oil, you can offset it by planting a large enough forest.

This would lead to a negative net carbon emission. The goal isn’t politically pragmatic, but it is conceptually simple, and will serve until somebody offers a better alternative.