In silicon carbide (SiC) thyristors, the turn-on time decreases with increasing temperature. Experimental data for 400-800 V and 2.6 kV 4H-SiC thyristors are analyzed. A qualitative analysis, analytical calculations, and computer simulations have been made to clarify the origin of this effect. It is shown that the temperature ionization of the Al dopand in the p(+)-emitter is mainly responsible for the effect. The hole concentration in the p(+)-emitter grows sharply with increasing temperature, making larger the injection coefficient of the p(+)-n junction. The role played by the temperature dependence of the carrier lifetime in the p(+)-emitter is demonstrated.