There are several Nobel Prizes that have some credibility attached to them (Physics, for instance, or Chemistry). The Nobel Peace Prize is not one of them.
For the past century, this has been an annual celebration of liberals pinning awards on fellow liberals. In this case, Europe asked "Who can we give an award to that is the epitome of our ineffective foreign policy and constant blaming of America? I know, that's easy! Obama!"
Note that Ronald Reagan did not receive a Nobel Peace Prize for vanquishing the Soviet Union without a nuclear war (as liberals claimed would happen).