Discovery of the Subtle

Abstract

Astute observers have long recognized that human activities have indirect, unexpected, and often deleterious effects on natural systems. George Perkins Marsh was probably the first to consider explicitly the indirect and cumulative effects of human activities, observing in 1864 that “[w]e are never justified in assuming a force to be insignificant because its measure is unknown, or even because no physical effect can now be traced to its origin” (Marsh 1965:465). The critical importance of understanding the interconnections between human activities and the natural world is even greater today than it was in the mid-nineteenth century as the pace and pervasiveness of human influence intensifies. There are ever-increasing human activities with currently subtle but potentially devastating effects.