Indoor skiing in the desert has become a symbol of Dubai’s status as a w    1    , modern metropolis. Originally a small fishing village, Dubai’s fortunes changed forever with the d    2     of oil in the 1960s. Since then, it has become the largest city in the United Arab Emirntes. But the rapid g    3     has come at a price. To power its cars and air-conditioning, the city has produced large amounts of carbon dioxide (CO2) from f    4     fuels. By 2006, Dubai had one of the I     5     ecological footprints in the world. But now it is making some big c    6    . To reduce its dependence on cars and lower its emissions, Dubai has invested in s    7     energy, green buildings, and a comprehensive public transportation system-Brightly Shining driverless trains now run b    8     the main roads. In addition, all new buildings must meet strict energy r    9    . Smart lighting and cooling systems must switch o    10     when no people are present in a room. New buildings must also use solar panels for water heating.