  The underlying Dirac point is central to the profound physics manifested in a
wide class of materials. However, it is often difficult to drive a system with
Dirac points across the massless fermionic critical point. Here by exploiting
screening of local moments under spin-orbit interactions in a Kondo lattice, we
show that below the Kondo temperature, the Kondo lattice undergoes a
topological transition from a strong topological insulator to a weak
topological insulator at a finite temperature $T_D$. At $T_D$, massless Dirac
points emerge and the Kondo lattice becomes a Dirac semimetal. Our analysis
indicates that the emergent relativistic symmetry dictates non-trivial thermal
responses over large parameter and temperature regimes. In particular, it
yields critical scaling behaviors both in magnetic and transport responses near
$T_D$.
