This fall, energy and the environment have taken a back seat to financial turmoil, national security and the wars that the nation is fighting on two fronts. But when voters head to the polls they need to know where both candidates stand on important policies concerning nuclear energy, offshore drilling and clean coal — to name a few. For a look at how John McCain and Barack Obama plan to tackle energy dependence and global warming, The Takeaway turns to Martin Smith. Guest: Martin Smith, FRONTLINE correspondent. Smith traveled the globe for FRONTLINE's upcoming documentary "HEAT," a global investigation into what big business and governments are doing to combat climate change. "HEAT" airs Tuesday, October 21 at 9 p.m. Eastern on PBS.