  Planets form in disks around young stars. The planet formation process may
start when the protostar and disk are still deeply embedded within their
infalling envelope. However, unlike more evolved protoplanetary disks, the
physical and chemical structure of these young embedded disks are still poorly
constrained. We have analyzed ALMA data for $^{13}$CO, C$^{18}$O and N$_2$D$^+$
to constrain the temperature structure, one of the critical unknowns, in the
disk around L1527. The spatial distribution of $^{13}$CO and C$^{18}$O,
together with the kinetic temperature derived from the optically thick
$^{13}$CO emission and the non-detection of N$_2$D$^+$, suggest that this disk
is warm enough ($\gtrsim$ 20 K) to prevent CO freeze-out.
