Global Warming Impacts on NW Salmon

1. Global Warming Impacts on NW Salmon Dr. Nathan Mantua Climate Impacts Group University of Washington November 18, 2005 Long Live the Kings 2005 Chairman’s Council Luncheon Climate Science in the Public Interest

2. What will the future bring?

3. Pop-culture perspectives It might be a good story, but it is not good science Likewise, the Day After Tomorrow scenario makes for an exciting movie, but it presents an extremely unlikely impact of global warming

4. Science of climate change • Thousands of peer-reviewed scientific papers • Intergovernmental Panel on Climate Change (IPCC) • Major reports in 1990, 1996, 2001, 2007 • 2001 report involved 637 contributing authors, 420 peer-reviews, then another review by government experts and policy-makers • Conclusions: • “An increasing body of observations gives a collective picture of a warming world and other changes in the climate system.” • “There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities.”

5. Science of climate change • 2001 White House request for advice from the US National Academy of Sciences • “… are there any substantive differences between the IPCC Reports and IPCC Summaries?” • National Research Council convened a panel of 11 leading US climate scientists to write the report • Conclusions: • “Greenhouse gases are accumulating in Earth’s atmosphere as a result of human activities, causing temperatures to rise … The committee generally agrees with the assessment of human-caused climate change presented in the IPCC scientific report …”

6. Three Key Points • global warming is a serious long term issue • the regional impacts of global warming are likely to increase stress on many PNW salmon populations • “All-H climate insurance” for NW salmon can alleviate the negative impacts of global warming

7. 21st Century NW temperature scenarios The latest climate model simulations call for +2 to +10 F NW temperature increases by 2100 - the uncertainty comes from 2 streams: (1) social factors and (2) geophysics

9. The main impact of a warmer climate: LESS SNOW for a ~3.6°F (2°C) warming Snoqualmie Pass 3022 ft

10. Springtime snowpack will decline, especially at the warmest locations + 4.1 ºF (2.3 ºC) & + 4.5% winter precipitation +2.3C, +4.5% winter precip

11. The coldest locations are less sensitive to warming + 4.1°F + 4.5% winter precip

12. Western Washington Precip Oct Feb Jun +3.6 to +5.4°F (+2 to +3°C) Streamflow patterns are temperature dependent

13. A warmer climate and flooding, stormwater & wastewater management • At mid-elevations more precipitation will fall as rain and less as snow, leading to an increased frequency of river flooding • a warmer atmosphere holds more moisture: theory and climate models suggest an increased intensity of precipitation • more intense rainfall events increase the risk of urban flooding and combined sewer overflows

14. Sea Level Rise scenarios depend on regional tectonics • tectonic processes and glacial rebound are causing South Puget Sound to subside and the Olympic Peninsula to uplift • this means that relative sea level rise will be greatest in South Puget Sound (~3.3ft by 2100), and least near Neah Bay (~1.3ft by 2100) • Wetland and marsh habitat will be lost near hardened shores

15. Climate impacts on salmon must be added to existing stresses across their full life-cycle

16. Impacts are cumulative … HABITAT CHANGE and DEGRADATION INCLUDING GLOBAL WARMING HARVEST PRACTICES HATCHERY PRACTICES

17. Temperature thresholds for coldwater fish in freshwater • Warming temperatures will increasingly stress coldwater fish in the warmest parts of our region A monthly average temperature of 68ºF (20ºC) has been used as an upper limit for resident cold water fish habitat, and is known to stress Pacific salmon during periods of freshwater migration, spawning, and rearing. +4.1 °F +3.4 °F

18. 134 lb marlin caught 40 mi. west of Westport, WA, Sept 2, 2005 Photo obtained from the Seattle Times web-archives Species distributions change with temperature From the Seattle Post-Intelligencer, October 20, 2005

19. Upwelling food webs in our coastal ocean Cool water, weak stratification high nutrients, a productive “subarctic” food-chain with abundant forage fish and few warm water predators Warm stratified ocean, few nutrients, low productivity “subtropical” food web, a lack of forage fish and abundant predators Recently, warm ocean years have generally been poor for NW chinook, coho and sockeye, but good for Puget Sound pink and chum salmon.

20. Global Warming and NW salmon Increased fall/winter flood events in snow melt basins Thermal barriers to spawning migrations higher summer stream temps • Thermal limits? • will intensified upwelling winds sustain subarctic habitat? • earlier spring snowmelt • will smolt migration timing shifts match timing shifts in the spring transition in coastal upwelling?

21. summary • global warming is a serious long term issue • the regional impacts of global warming will increase stress on many PNW salmon populations • Warmer, lower summer stream flow; higher flows in winter • “all-H climate insurance” for NW salmon can alleviate the negative impacts of global warming • steps taken to increase abundance, diversity, and distribution are needed to support adaptation • existing stresses (Harvest, Hatchery, Hydropower and Habitat problems) will need to be alleviated to do this • reduce greenhouse gas concentrations to slow and eventually arrest global warming

22. A new report by the UW’s Climate Impacts Group for the Puget Sound Action Team • Available online: • cses.washington.edu/cig

23. Columbia River Basin The Climate Impacts Group A NOAA-funded interdisciplinary research and education team at the University of Washington cses.washington.edu/cig