Green Towers?

Via Matt Yglesias, I happened upon this nice little piece by Lisa Chamerlain in New York. Chamberlain's article details the idea of Dr. Dickson Despommier of Columbia University to build vertical farms, or sky farms. Essentially, Despommier believes that we could build these farms in urban areas and they would allow for the reforestation of current farmland. Despommier insists that this is the only way to truly combat global warming. I must say that this isn't exactly my area of expertise but it seems like an idea worth exploring.