Your 4.9-ounce iPod is responsible for at least 200 times its weight in greenhouse-gas emissions.When you bought your last Apple iPod, you may have been aware that it had been manufactured at a factory in China, perhaps the Foxconn plant in Shenzhen in the province of Guangzhou. (Let's put aside for the moment the working conditions there.) You may have been aware too that in manufacturing your electronic marvel, the Shenzhen plant emitted roughly 25 pounds of the greenhouse gas carbon dioxide. It's even possible that you were aware of the 9-10 pounds of CO2 emitted in transporting the device …