Many scientists despair of ever putting the genie back in the bottle. In other instances, though, nature tends to spring back once the cause of disturbance is removed. Depleted fish populations recover once fishing stops. Forests and grasslands retake abandoned farmland, especially when given a helping hand by restorationists. Some ecosystems return to health when cleansing processes like fire, on which they depend, are restored.
Rivers tend to cleanse themselves once pollutants are no longer dumped in.
The problem is to get through the 21st century, and especially the next 50 years. Few if any scientists go so far as to say that what people know as the natural world will simply disappear, to be superseded by some high-tech virtual reality. But it is widely considered a sure bet that many species will vanish. Many kinds of ecosystems could disappear from the earth. Many genetic resources could be lost, including some that might offer the promise of lifesaving medicines and improved food production.