Climate change continues to pose considerable challenges and uncertainties for fish and wildlife restoration and mitigation actions in the Columbia River Basin. In this report, the ISAB uses information from peer-reviewed literature and a series of technical briefings from scientists and managers to describe what’s been learned since the ISAB’s initial Climate Report was completed in 2007 . The current report’s focus is on restoration and mitigation practices that could best support a climate-resilient ecosystem in the future.
Shifts in environmental conditions since the 2007 report underscore the rate and magnitude of temperature and hydrological changes over this short period (i.e., decades rather than centuries). The most evident shifts in the Pacific Northwest and Columbia River Basin include:
Increases in mean air temperature, consistent with global patterns Increases in mean inland water temperature Accelerating air and water temperature increases, often occurring as extreme events, rather than gradual and continuous changes More dramatic changes in the interior Columbia River Basin than in coastal areas Although less certain, altered precipitation patterns including 1) shifts in timing of annual precipitation to winter months, 2) increasing precipitation intensity, 3) increasing frequency of rain-on-snow events at high altitudes where snowpack persists (although rain-on-snow events will decrease at lower elevations due to snowpack declines), and 4) an earlier onset of winter and spring flows – all of which tend to alter river discharge patterns throughout the basin Rising frequency of unprecedented heat events in the ocean (e.g., in 2015 and 2021) and other disruptions of Pacific Ocean-atmosphere patterns (e.g., El Niño/La Niña) Advances in analytical techniques and regional datasets enable local projections of the likely impacts to key species and communities, enhanced understanding of the spatial variability of impacts across the basin, and evidence for the importance and impacts of extreme heat events on coldwater fish. Research has also clarified how climate change overlaps with other anthropogenic impacts, which puts migratory species like salmon particularly at risk.
Planning for climate resilience in the basin has also advanced. Given the availability of predictive analytical tools, emphasis is now shifting toward prioritization of limited resources for the greatest ecological benefit. The Columbia River Basin’s Tribes have taken a leadership role in developing tools for resilience assessment, planning, and prioritization as have federal agencies, academic scientists, and local organizations. A wide range of programs and frameworks are summarized in this report, including innovative programs that encompass improving model and data-centered analyses, increasing transparency of decision making, and youth education and engagement.
Specific practices to increase climate resilience in the basin include protecting and reconnecting climate refuges, restoring connectivity of rivers with their floodplains and their headwaters, engineering practices that emphasize adaptability and dynamism, and salvage and captive rearing of particularly imperiled populations.
The ISAB concludes the report with seven recommendations for moving the Columbia River Basin’s fish and wildlife toward climate resilience:
Strategic and transparent prioritization of actions that considers other stressors intersecting with climate change is important at the outset of project planning. Maintaining and enhancing physical habitat and species’ life history diversity are priorities for increasing climate resilience. Climate-resilient habitats need more physical space, more temporal dynamism, and more innovative monitoring. Policy and regulations need to be adaptable and collaborative. Considering reciprocity of actions through a Tribal ecological and cultural framework will promote climate resiliency. Engaging a broad public constituency will increase the scale and benefit of projects. While some knowledge gaps exist, the current scientific foundation supports taking immediate action toward more climate-resilient restoration. Achieving ecological resilience to changing climatic conditions for an ecosystem as large and diverse as the Columbia River Basin is a complex and enduring endeavor, especially given the legacy of alterations the basin has experienced. Climate change will overlay and amplify impacts to fish and wildlife from other ecosystem stressors, including overfishing, habitat fragmentation and degradation, hydrosystem operations, and spread of non-native species. In short, climate change does not negate the continuing need to restore habitat connectivity and complexity, meet basic ecological flow needs, connect lateral floodplains, deter predators, and other similar actions. It is another anthropogenic disruption to the ecosystem that warrants robust restoration and protection efforts integrated with other ongoing efforts.
