When author and former UA Journalism instructor, Alan Weisman wrote his book "The World Without Us," he hoped that it would help readers realize the damage humans do to nature.

His book plays out a scenario where people everywhere are wiped out. Once the world is cleared of all humans, he said nature would be able to heal very quickly.

"Nature could regroup, refill empty niches where we've extinguished species and recover and be rather beautiful," Weisman said.

Through this book, as well as journalistic research, Weisman has been looking into the planet's sustainability of large populations. And this is how his new book, "Countdown," came about.

"Countdown" looks at fast, acceptable and affordable ways human presence on Earth could reach a positive balance, in the wake of an ever growing population.

Weisman said believes that women's education is the best solution for controlling over population.

"A woman who is in school, tends to defer her child bearing until she's done with her studies," he said. "And then, she's got something interesting, important and very helpful to her family to do, but you can't do that when you've got seven kids hanging on you, so they tend to have two children or fewer."