NEW : Bush warns of `` planetary emergency , '' announces new ad campaign . Ex-President Clinton says Gore has warned of dangers for 2008 . Source : Gore wo n't use prize as springboard to enter 2008 presidential race . U.N. : In recent weeks , Gore has been the target of a campaign to persuade him to enter the 2008 presidential race . President Gore pleased that Al Gore , U.N. panel won peace prize .
NEW : Bush warns of `` planetary emergency , '' announces new ad campaign . Ex-President Clinton says Gore has warned of dangers for 2008 . Source : Gore wo n't use prize as springboard to enter 2008 presidential race . U.N. : President Gore pleased that Al Gore , U.N. panel won peace prize .