Greenhouse gases are vital to life on Earth, but the growing concentration of certain gases, such as carbon dioxide, is throwing the planet's delicate balance out of whack. NASA is on the case, studying carbon dioxide on a global scale and its effects on our weather and climate. More about carbon: http://climate.nasa.gov/vital-signs/carbon-dioxide/ http://earthobservatory.nasa.gov/Features/CarbonCycle/page1.php More 'NASA's Earth Minute' videos: http://climate.nasa.gov/climate_resource_center/ea