If a population grows larger than the carrying capacity of the environment then

If a population grows larger than the carrying capacity of the enviromment, there will be more organisms than the environmental can support

So, if a population grows larger than the carrying capacity of the environment, there will be more organisms than the environment can support. The environment cannot sustain this number, so organisms will die until the population is under the carrying capacity. So, the death rate may rise to reduce the population size.