  The vertical temperature structure of a protoplanetary disk bears on several
processes relevant to planet formation, such as gas and dust grain chemistry,
ice lines and convection. The temperature profile is controlled by irradiation
from the central star and by any internal source of heat such as might arise
from gas accretion. We investigate the heat and angular momentum transport
generated by the resistive dissipation of magnetic fields in laminar disks. We
use local one-dimensional simulations to obtain vertical temperature profiles
for typical conditions in the inner disk (0.5 to 4 au). Using simple
assumptions for the gas ionization and opacity, the heating and cooling rates
are computed self-consistently in the framework of radiative non-ideal
magnetohydrodynamics. We characterize steady solutions that are symmetric about
the midplane and which may be associated with saturated Hall-shear unstable
modes. We also examine the dissipation of electric currents driven by global
accretion-ejection structures. In both cases we obtain significant heating for
a sufficiently high opacity. Strong magnetic fields can induce an order-unity
temperature increase in the disk midplane, a convectively unstable entropy
profile, and a surface emissivity equivalent to a viscous heating of $\alpha
\sim 10^{-2}$. These results show how magnetic fields may drive efficient
accretion and heating in weakly ionized disks where turbulence might be
inefficient, at least for a range of radii and ages of the disk.
