Climate change and land use change can affect multiple infectious diseases of humans, acting either independently or synergistically. Expanded efforts in empiric and future scenario-based risk assessment are required to anticipate problems. Moreover, the many health impacts of climate and land use change must be examined in the context of the myriad other environmental and behavioral determinants of disease. To optimize prevention capabilities, upstream environmental approaches must be part of any intervention, rather than assaults on single agents of disease. Clinicians must develop stronger ties, not only to public health officials and scientists, but also to earth and environmental scientists and policy makers. Without such efforts, we will inevitably benefit our current generation at the cost of generations to come.