The way in which we view environmental issues changes, often with remarkable rapidity.
The 'Earthrise' photo from Apollo II (1969) instilled a general perception of the Earth as a fragile, unified ecosystem in the world population.
During the 1980-90's the focus of issues moved from local to national to international due to increased awareness of transboundary nature, or spatial extent of issues such as marine and air pollution, habitat loss.
Focus on connections: population, pollution and resource depletion, once viewed as independent issues, now seen as related and in the broader context of sustainable development, climate change and biodiversity loss.