We study the well known
variational problem proposed by Calabi: Minimize the functional ∫Msg2dvg among
all metrics in a given Kahler class. We are able to establish the existence of the
extremal when the closed Riemann surface has genus different from zero. We have
also given a different proof of the result originally proved by Calabi that: On a closed
Riemann surface, the extremal metric has constant scalar curvature on a closed
Riemann surface, the extremal metric has constant scalar curvature, which originally
is proved by Calabi.