Environmental and climate changes will challenge systems in different dimensions; heat waves, for example, stress infrastructure, energy, human and animal health, and agriculture. Climate change— observed or anticipated—almost certainly will become an increasingly integral component of how people view their world, especially as populations are projected to swell in those areas most vulnerable to extreme weather events and sea-level rise, including coastal megacities and regions already suffering from water scarcity. Many of the ecological and environmental stresses from climate change—and the infectious diseases it will affect—will cut across state borders, making coordination among governments and international institutions crucial to effective responses. Policies and programs to mitigate and adapt to these challenges will spur opportunities for those well-positioned to benefit.