Reviews Climate CO2 Rising: The World’s Greatest Environmental Challenge by Tyler Volk Share this: Share via email (Opens in new window) Email Click to share on Facebook (Opens in new window) Facebook Click to share on Reddit (Opens in new window) Reddit Click to share on X (Opens in new window) X Click to print (Opens in new window) Print By Science News March 13, 2009 at 1:10 pm A biologist explains the carbon cycle. CO2 Rising: The World’s Greatest Environmental Challenge by Tyler Volk MIT Press, 2008, 223 p., $22.95