No, warmer would be bad.
A warmblooded animal, such as mammals with their core temperature of ~37ÂC for mammals and few degrees more for birds, constantly produces heat. That is heat must go somewhere, otherwise it would lead to overheating. So the only choice is to run at a temperature which is above that of the environment. Once those temperatures come too close to each other, all animals reduce their activity more and more to prevent said overheating.
So, a jump in global temperature, i.e. one that is faster than evolution can keep pace with, would pose a serious threat to animals in areas where the gap between their core temperature and the environment is reduced.