Ominous trends in nature recreation.

C onservation science is replete with analyses of threats to biodiversity. The IUCN even has a formal taxonomy of threats to imperiled species that can be used to tally up global inventories of threats across taxa or geographies (1). Habitat loss and habitat degradation are touted as the greatest threats, with global warming now also recognized as a major problem along with species introductions (2). However, in a recent issue of PNAS, Pergams and Zaradic (3) show a trend in human behavior that ultimately may be far more foreboding for the environment than even declining tropical forest cover or increasing greenhouse gas emissions: widespread declines in nature-based recreation. The importance of human behavior and attitudes to our environmental future is not a new idea. It is this connection between human decisions and environmental outcomes that spurred Paul Ehrlich and Donald Kennedy (4) to call in 2005 for a global assessment of human behaviors. What is less clear is how human environmental attitudes get shaped and what causes those attitudes to change through time. One hypothesis is that the environmental choices humans make depend to a great measure on the connection between humans and nature, and on a broad human appreciation of nature’s constraints and workings. Although attention to the human connection with nature might seem remote from the more immediate peril of a bulldozer, there is no doubt that investment in and protection of the environment will require human choices and some changes in human behavior. Just as we track trends in species loss and forest cover as key environmental indicators, we need to pay attention to trends in human behaviors and attitudes as the ultimate drivers of global change.