Eric Toensmeier is an author and expert on the link between agriculture and climate change who has recently completed a book, The Carbon Farming Solution, drawing on his deep knowledge of sustainable agriculture, including agroforestry and permaculture. More about the book here: http://carbonfarmingsolution.com/ . Also, check out Tim Flannery's work here: http://www.theguardian.com/books/2011/mar/14/tim-flannery-here-on-earth