Too few resources, too many people. That's the received wisdom in most of the environmental movement, mainstream or radical. But can that assumption withstand close scrutiny? Not according to population scholar Betsy Hartmann, who interrogates whether overpopulation is a main -- or the main -- cause of our ecological woes. She also discusses the far Right's courting of liberal environmentalism. (Encore presentation.)

Huge tracts of fertile land in Africa are being gobbled up, not by Africans but by foreign investors with deep pockets. Many African governments, in cahoots with the World Bank, are doing all they can to encourage these land deals, but the consequences for ordinary Africans and the environment are staggering. Joan Baxter has done extensive on-the-ground investigation in Mali and Sierra Leone.

Why do some civilizations endure, while others implode? What role might the environment play in their survival or demise? Jared Diamond argues that much can be learned about our own future by looking at the trajectories of past societies and their relationship with nature. The controversial scholar has been criticized for environmental determinism, but his work is nothing if not thought-provoking.

Too few resources, too many people. That's the received wisdom in most of the environmental movement, mainstream or radical. But can that assumption withstand close scrutiny? Not according to population scholar Betsy Hartmann, who interrogates whether overpopulation is a main -- or the main -- cause of our ecological woes and discusses the far right's courting of liberal environmentalism.

Could it be that what we don't eat is destroying our environment? Historian Tristram Stuart argues that the vast amount of food that is wasted by manufacturers, supermarkets, farmers, and consumers -- up to 50 percent of food grown in this country -- has massive ecological consequences, leading to the depletion of the oceans, the decimation of rainforests to grow grains for livestock, and mountains of methane-emitting landfills. (Encore presentation.)

California has 1100 miles of coastline; most of it is eroding and all of it is changing in myriad ways. Gary Griggs has written a book about the coast's history, geology, climate, and resources. He also addresses the impact of rising sea levels and the history of oil extraction off California's coast.