sentences:  The prize will initially only be open for five years, with ideas assessed by a panel of judges including Richard Branson, Al Gore and Crispin Tickell (British diplomat), as well as scientists James E. Hansen, James Lovelock and Tim Flannery.If the prize remains unclaimed at the end of five years the panel may elect to extend the period.Around two hundred billion metric tons of carbon dioxide have accumulated in the atmosphere since the beginning of the industrial revolution, raising concentrations by more than 100 parts per million (ppm), from 280 to more than 380 ppm.