Natural populations can suffer catastrophic collapse in response to small changes in environmental conditions as a result of a bifurcation in the dynamics of the system. We have used laboratory microbial ecosystems to directly measure theoretically proposed early warning signals of impending population collapse based on critical slowing down. Our experimental yeast populations cooperatively break down sugar, meaning that below a critical size the population cannot sustain itself. The cooperative nature of this microbial growth makes the population susceptible to “cheater” cells, which do not contribute to the public good and reduce the resilience of the population.