David Hansen : We know what to do to prevent climate catastrophe . Ending emissions from coal and stopping development of tar sands are key , he says . The opinions expressed in this commentary are solely those of James Hansen . It 's time to establish a fee for companies that emit carbon , Hansen says . Hansen : It would be unjust to bequeath to our descendants a desolate land .
David Hansen : We know what to do to prevent climate catastrophe . Ending emissions from coal and stopping development of tar sands are key , he says . It 's time to establish a fee for companies that emit carbon , Hansen says . Hansen : It would be unjust to bequeath to our descendants a desolate land .