Climate change is altering the dynamics of common pool resources around the world. We design an experimental game that varies both the flow of natural resources and the group punishment mechanisms available to resource users. Our experiments show that subjects are more likely to over-harvest when resource flows are high. But group punishment mechanisms that rely on social ostracism (as opposed to fines or fees) are more effective at mediating the desire to over-harvest when resources are booming. This suggests that collective management systems based on social norms, exclusion, and ostracism may be more resilient to unexpected changes in resource dynamics and supports bottom-up, as opposed to top-down, management of common pool resources.