Environmental problems regularly cut across levels defined in biophysical and socioeconomic terms. Although some problems (e.g., harvesting a local stock of fish sustainably, cleaning up a spatially limited toxic waste site) are local in scope, others involve much broader domains. Climate change, to take a prominent example, is a multilevel concern. Human actions anywhere on the planet (e.g., burning coal in a specific power plant, using gasoline in an individual automobile, cutting trees in a particular forest) can add to concentrations of greenhouse gases in the atmosphere and, therefore, contribute to climate change on a planetary scale. Climate change, in turn, affects the well-being of people everywhere, though the nature and severity of the impacts will depend on a range of biophysical and socioeconomic factors. It is possible that some may benefit, at least in the early stages, from the impacts of climate change. But no one will be unaffected, especially as its pace accelerates in the coming decades. Much the same is true regarding other large-scale biophysical changes. Sea-level rise is a matter of utmost concern to those residing in a host of low-lying island states; desertification is a major threat to those engaged in dryland agriculture in many places; melting glaciers pose a severe challenge to

those whose livelihoods are tied to rivers that currently flow freely throughout the year.