Chapter 2 - Climate Change and Interactions With Multiple Stressors in Rivers

Climate change is impacting river networks, many of which are also impacted by current stressors or have been subjected to a legacy of stressors. The most common projections of climate change impacts on rivers involve changes in timing and magnitude of discharge, and increases in extreme events of both peak flows and low flows and in stream temperature. However, model scenarios of the timing, magnitude, and duration of projected changes in precipitation and runoff are highly variable. There is generally a strong agreement that stream temperatures will increase with climate change, but the magnitude of change has a high uncertainty because of the interactions of the drivers of temperature with multiple other factors, including discharge, source of streamflow, and status of riparian vegetation. Direct observations of climate impacts on rivers are challenging to disentangle from the concurrent changes due to multiple factors that affect runoff and water temperature as well. Due to the number of rivers that have changes in land use and riparian vegetation cover, modifications to channel morphology, and increased water extraction and damming, the clear identification of changes to discharge and water temperature that can be attributed only to climate change is limited. The potential outcome of combined stressors might be to amplify or lessen the effects of each separate stressor. Predicting whether interactions among climate change and other stressors will be linear, additive, synergistic, or some other combination remains difficult. Ultimately, the conservation of river ecosystems depends on how well these issues are understood and addressed, as well as on solutions that allow them to coexist with multiple stressors.
keywords: Stressors, Climate change, Streams, Rivers, Runoff, Water temperature, Ecosystem responses