Marianne Engelman Lado, Earthjustice & Alexis Baden Mayer, Organic Consumers Association & David Murphy, Food Democracy Now
This past week - two counties in Oregon passed laws banning GMO's - much to the dismay of genetically modified food companies like Monsanto. Where does the fight to ban GMOs stand today - and how can Americans fight back against mountains of corporate cash from the GM industry?

Eating organic is all the rage these days - but could it actually help save the planet from climate devastation? As the reality of global climate change continues to sink in - scientists - activists - and lawmakers all across the world are working to find new ways to fight back against greenhouse gas emissions before it's too late. Thom's guest for tonight's Conversations With Great Minds - Tom Newmark - is one such person. A former corporate attorney turned organic farmer - Tom is now at the forefront of the movement to use agriculture to fight global warming. He is the co-founder of the new non-profit the Carbon Underground as well as the co-owner of Finca Luena Nueva - an organic farm in Costa Rica. Tom is also the co-founder of Sacred Seeds - a trustee of the American Botanical Council.

Global warming is real - and possibly even worse than we've been told. Could it lead to the destruction of human civilization within just a few decades? For tonight's Conversations With Great Minds - I'm joined by Guy McPherson -Professor Emeritus of Natural Resources - Ecology - and Evolutionary Biology at the University Arizona. Guy is one of America's most influential experts on global warming - and writes about a variety of climate change-related issues for the Arctic News and his own website - Nature Bats Last. In the field of climate science - Guy is best known for his assertion that runaway global warming is already on a path to cause the extinction of the human race - an idea he has written about in his book - "Going Dark."

Could encouraging more private investments in solar power and other forms of clean energy help make renewable forms of energy more popular in America - and lead to the downfall of dirty fossil fuels? That and more in our Conversations with Great Minds with Billy Parish. Billy is the co-founder and president of Mosaic - a solar power investment platform. In 2002 - Billy dropped out of Yale University to help found the Energy Action Coalition - which quickly grew into the largest youth advocacy organization in the world working on the climate change crisis. He's been honored by Rolling Stone magazine as a "Climate Hero," and by the Utne Reader as one of the "50 Visionaries Who Are Changing Your World." Billy is also the co-author of the book, "Making Good: Finding Meaning, Money and Community in a Changing World."

During his first presidential campaign - then Senator Barack Obama said that people would look back on his time in office and say that that was the "moment when the rise of the oceans began to slow and our planet began to heal" But has he really lived up to his own high standard on climate policy? I'll ask Dr. Michael Dorsey in tonight's Conversations with Great Minds. Dr. Michael Dorsey is currently the Interim Director of the Energy and Environment Program at the Joint Center for Political and Economic studies - where he works to combine the study of climate policy with the study of social justice issues. Before taking this position - Dr. Dorsey taught environmental studies at Wesleyan University and Darthmouth University. He was also a member of Barack Obama's energy and environment campaign team in 2008 and is on the Environmental Protection Agency's national advisory committee.

Shane Bauer, Joshua Fattal and Sarah Shourd - A Sliver of Light: Three Americans Imprisoned in Iran, all join Thom. It was a story that captivated the world: Three Americans hikers captured by Iran - and thrown into solitary confinement for over a year.

For tonight's Conversation With Great Minds - I'm joined by one of the country's foremost experts on nuclear security and nuclear nonproliferation. As the president of the global security organization the Ploughshares Fund - Jospeh Cirincione is on the frontline of the fight to prevent the spread of dangerous nuclear weapons. He is also a member of Secretary of State John Kerry's International Security Advisory Board and the Council on Foreign Relations. Before taking his position at the Ploughshares Fund in 2008 - Joseph worked on nonproliferation issues for the U.S. House of Representatives - Center for American Progress - and the Carnegie Center for International Peace. He is the author of a number of books on nuclear weapons policy - including his latest -"Nuclear Nightmares: Securing the World Before It Is Too Late" - a fascinating - and often sobering - look at the reality of modern day nuclear destruction.