  The spontaneous pair production of charged scalars in a near extremal
Kerr-Newman (KN) black hole is analytically studied. It is shown that the
existence condition for the pair production is equivalent to the violation of
the Breitenlohner-Freedman bound in an AdS$_2$ space. The mean number of
produced pairs in the extremal black hole has a thermal interpretation, in
which the effective temperature for the Schwinger effect in the AdS$_2$ space
persistently holds, while the mean number in the near extremal black hole has
an additional factor of the Schwinger effect in the Rindler space. In addition,
the holographic dual conformal field theory (CFT) descriptions of the charged
scalar pair production are respectively realized both in the $J$ and $Q$
pictures in terms of the KN/CFTs correspondence.
