A version of this article originally appeared in The Observer.

Investigative journalist and author Fred Pearce has a new book out this week: The Land Grabbers: The New Fight Over Who Owns the Earth, which explores "how Wall Street, Chinese billionaires, oil sheiks, and agribusiness are buying up huge tracts of land in a hungry, crowded world." Here he answers questions about the book and his long career reporting on environmental challenges.

Q. What inspired you to write The Land Grabbers?

A. Over the last few years, I became aware of this hidden revolution taking place around the world: the buying up of vast swaths of land by foreign entities from beneath its occupiers. Soaring grain prices in 2007/2008 led to countries such as Saudi Arabia and South Korea worrying about their national food security and buying up overseas land. Then speculators and investors started piling in on the back of that. The net result is that poor farmers and cattle herders across the world are being thrown off their land. Land grabbing is having more of an impact on the lives of poor people than climate change. No one has put together the global picture of land grabbing so I wanted to take a closer look.