Ridley notes that with genetically engineered crops, synthetic fertilizers, and Roundup to control weeds, the trend of feeding ever more people with less land could be continued. The biggest obstacle to returning land to its wild state is organic farming. Currently we are using 38 percent of the Earth’s land for growing food or grazing animals; at 1961 levels of productivity we would need to be using 82 percent of the land.
Organic farmers won’t use genetically engineered crops, so they spend a lot more time and energy fighting pests. Organic farmers won’t use Roundup and other herbicides, so they plow the weeds under, which kills a lot of small animals and loosens the soil enough that it erodes (or sometimes they resort to flame-throwers). Organic farmers won’t use standard fertilizer, but only manure from cows, which means we’ll need a lot more cows running around.