  We predict that graphene is a unique system where disorder-assisted
scattering (supercollisions) dominates electron-lattice cooling over a wide
range of temperatures, up to room temperature. This is so because for
momentum-conserving electron-phonon scattering the energy transfer per
collision is severely constrained due to a small Fermi surface size. The
characteristic $T^3$ temperature dependence and power-law cooling dynamics
provide clear experimental signatures of this new cooling mechanism. The
cooling rate can be changed by orders of magnitude by varying the amount of
disorder which offers means for a variety of new applications that rely on
hot-carrier transport.
