Peak Ecological Water And Its Shift Under Climate Change: Case Studies From Peru And Pennsylvania

In most watersheds, as withdrawals for human needs increase, the ecological services provided by the same water are in decline. At a certain point, the value of water provided for human use is equal to the value of the ecological services, and beyond this point, ecological disruptions exceed the benefits of increased water extraction; this point is referred to as “peak ecological water." In addition, the human and ecological benefits may occur at different spatial and temporal scales. Climate change may be shifting the point of peak ecological water in new and unpredictable ways, and two case studies provide insights into how those changes may be context dependent. In the first case study, we examine the ecological and humans services provided by high altitude peat bogs termed bofedales that are supported by glacial melt water; the predicted loss in glacial volume changes the timing and amount of water delivery, with implications for the balance between human supply uses and the ecological services provided by these systems. The second case study investigates the predicted impact of hydrological changes associated with climate change on the ecological services provided by wetlands in Pennsylvania; the point of peak ecological water is predicted to shift in this case, as well. The shifts in hydrology that may be coming as a result of climate change may be far greater than the shifts that we have learned to manage in the recent past; a new generation of management and assessment tools will be required.