most immediate risk from climate change and is in desperate need of all the help it cacan get to adadap. host: on particucularly bad da, it can be hard to tell where you are -- cairo, paris, teheran? smog is a major problem in many cities. the international energy agency estimates that air pollution kills over six million people each year. smog is a huge issue in china, and the government is only slowly beginning to get a handle on the problem, helped along by vast projects in the field of renewables. reporter: the dream of a smog-free world is taking shape here. over 1000 kilometers from beijing in northwestern china, the largest solar array in the world is going up. ningxia a is a small a autonos regi with sisix million inhabitatants, plenty y of suns, vast open n spaces, and d te ambition to become a world leader in the field of solar energy. zhang quan is convinced his country is on the right path. the engineer wasasroud to be one of t those selecteted to get e project t up and runnining. zhang: renewable energies are a historical opportunity. we can cut coal consumption by 800,000