1. Marketa McGuire Elsner
Washington State
Climate Change
Impacts Assessment:
HB 1303 Key Findings
UW Climate Impacts Group
Marketa McGuire Elsner
Jeremy Littell
JISAO CSES Climate Impacts Group
University of Washington
Washington State University
Pacific Northwest National Laboratory
Talk about the climate in the Pacific Northwest and how it has changed over the last years and then how it might continue to change into the future. The purpose is to provide some background and context for the discussions here today surrounding sustainability in water and wastewater industry and minimizing our vulnerabilities in a changing climate.
Climate science in the public interest

2. Project Team Forests Scenarios (D. McKenzie, J. Littell)
CIG, UW, USFS, Univ. ID
Coasts
(D. Huppert)
CIG, UW
Urban Stormwater Infrastructure
(A. Steinemann, D. Booth)
UW, Stillwater Sciences, King Co. Water and Land Resources Div., Northwest Hydraulic Consultants
Human Health
(R. Fenske)
UW, WSU, Institute for Chemical Process and Envir. Tech. - Canada, CA Air Resources Board
Adaptation
(L. Whitely-Binder)
Scenarios
(E. Salathé, P. Mote)
CIG, UW, PNNL
Hydrology and Water Resources
(D. Lettenmaier, M. Elsner)
CIG, UW
Energy – Hydropower
(A. Hamlet)
Agriculture & Economics (Stockle, Scott)
WSU, USDA ARS, PNNL
Salmon
(N. Mantua)
CIG, U 2

3. Assessment Overview: Study Region

4. Overall Assessment Approach
Focus on regional integration

5. Scientific progress, assessment limitations
Vertical integration of climate change projections
Wide range of research areas
Narrowing of uncertainty with many climate models
Quantified impacts and ranges for decision making
Limitations:
Modeling climate variability (interannual, decadal)
Interactions or synergies between impacts
Uncertainty in climate and projections
There may be thresholds we have yet to understand
Limitations:
Climate variability and timing of impacts
This refers to our inability to directly model climate variability – most of the GCMs don’t do very well at this, and in any case most of the sectors use a GCM “mean” for future projections. As such, it is possible the projected impacts may vary substantially in the timing of their arrival on the planning horizon. For example, projections I might make about WHEN there will be a doubling of area burned in the PNW could be off by a full analysis window (projection for the 2040s might not be realized until the 2080s) if we had a cool window of climate associated with PDO or other atmosphere/ocean interactions.
Interactions between impacts (synergy)
This refers to the idea that different impacts might exacerbate or cancel each other and the true conditions may be better or worse than what we state. Usually. The feedbacks DON’T cancel each other, but we can’t usually rule that out.
Uncertainty in climate and projections
This one is basic – there are several sources of uncertainty though in our understanding of climate. One is that all the models have different projections, and some things they notably disagree on. We deal with that fairly well by consulting many models and approaches. Another is that the forcing factors could shift based on what we or Nature do. A third is that there may be thresholds out there that we don’t understand.
Thresholds outside range of modern variability
This refers both to climate and impacts – the 1303 report frequently uses statistical modeling in place of process modeling, but both are subject to the potential for the nature of the system, whether climatic, hydrologic, ecological, or human – to be different outside the bounds of the observed record.
Progress:
Sector integration and resolution of inquiry
Unless I am mistaken, NO integrated assessment has before been THIS integrated. This starts with hemispheric climate models and moves down to sub-basin watersheds and impacts at that level. Snowpack and changes in potential evapotranspiration appear to be unifying themes of impacts. And we follow it through to adaptation – that’s key too.
Scope: sector diversity and geographic potential
We have atmosphere, ocean, mountains, water, fish, trees, potatoes and apples, people and their dollars, all in one big report,
Narrowing of uncertainty with many climate models
We’ve at least controlled, if not eliminated, the nature of uncertainty associated with future climate projections across models (not necessarily with variability though, see above), and that’s one that people often have a difficult time gettting around in decision making.
Quantified impacts and ranges for decision making
At least for many sectors, there are hard numbers about the projected ranges of impacts at different locations or in different ecosystems. That’s a great leap forward, right?

6. Projected Increases in Annual PNW Temperature
* Compared with average
2080s
2040s
2020s
+5.9°F
+3.5°F
+2.2°F °C
Figure 3. Simulated temperature (change, top panel) and precipitation (% change, bottom panel) for the 20th and 21st Century climate model simulations. The black curve for each panel is the weighted average of all models during the 20th Century. The colored areas indicate the range (5th to 95th percentile) for each year in the 21st Century. All changes are relative to averages. °F
Mote and Salathé, 2009

7. Projected Changes in Annual Precipitation
* Compared with average
Figure 3. Simulated temperature (change, top panel) and precipitation (% change, bottom panel) for the 20th and 21st Century climate model simulations. The black curve for each panel is the weighted average of all models during the 20th Century. The colored areas indicate the range (5th to 95th percentile) for each year in the 21st Century. All changes are relative to averages.
Changes in annual precipitation averaged over all models are small but some models show large seasonal changes, especially toward wetter autumns and winters and drier summers.
Mote and Salathé, 2009

8. Regional climate model projections
Figure 4. Differences between a regional climate model (WRF) and a global climate model (CCSM3) for projected changes in fall precipitation (September to November top) and winter temperature (December to February, bottom) for the 2040s. The global model produces a regionally averaged 11.7% increase in precipitation, but the regional model provides more detail (top), projecting some areas of increase (green) and some of decrease (brown) compared to the global model. Note that large increases are seen on windward (west and southwest) slopes and smaller increases on leeward (east and northeast) slopes. The global model produces a 3.6°F regionally averaged increase in winter temperature, while the regional model produces a statewide average 2.5°F warming. There are greater increases (darker red) at higher elevations and windward slopes, particularly the Olympic Mountains, North Cascades, and central Cascades. These differences illustrate the value of regional climate models for identifying sub-regional patterns and differences. The patterns of climate change differ depending on the global model being downscaled (we present only one here); nevertheless, the local terrain has a consistent influence on the results.
Salathé et al, 2009

9. Hydrology and water resources
Figure 5. Summary of projected changes in April 1 snow pack (measured as snow water equivalent, or SWE) for the 2040s, scenario A1B. Statewide decline relative to is 37%-44%.
37-44% change (B1/A1B)
* Compared with average
Elsner et al. 2009 9

10. Include in this discussion impacts impacts to urban water supplies of the Puget Sound (namely their system are robust to climate change if population remains flat) and Yakima irrigation supply (namely the system will be water short more often, which will impact junior water users significantly)
Mantua et al. 2009

11. Yakima Economics - Production Value
These impacts are cases with CO2 fertilization. Physical impacts on junior lands are buffered somewhat by price increases and by largely unchanged production on senior land.
Reservoir system will be less able to supply water to all users, especially those with junior water rights.
Junior and senior water user averaged, impacts include CO2 fertilization
Production decreases by 5% in 2020s, 16% in 2080s (relative to historical)
Production values are buffered somewhat by price increases and largely unchanged production on senior water user lands
Vano et al. 2009b

12. Puget Sound Basin municipal supply - current demand
Tacoma, water allocations closer to current system capacity
Municipal and Industrial, reliability measures differ across systems
With current demands, system reliability able to accommodate changes (A1B)
With demand increases, system reliability reduced, conservation measures matter
Note: simulations do not include adaptation 1% 7% 0%
Everett, largest system capacity
* Projections compared to water year average
Vano et al. 2009a

13. Energy
Annual hydropower production is projected to decline by a few percent due to small changes in annual flow, but seasonal changes will be substantial.
Winter hydropower production is projected to increase by about % by the 2020s, % by the 2040s, and 7%-10% by the 2080s (compared to water year )
Summer energy production is projected to decline by 10% by the 2020s, 15% by the 2040s, and 20% by the 2080s. At the same time summer cooling demands may increase by 400%
Figure 3. Simulated temperature (change, top panel) and precipitation (% change, bottom panel) for the 20th and 21st Century climate model simulations. The black curve for each panel is the weighted average of all models during the 20th Century. The colored areas indicate the range (5th to 95th percentile) for each year in the 21st Century. All changes are relative to averages.
Hamlet et al. 2009 13

14. Energy
Figure 7. Long-term average system-wide energy production from the Columbia River hydro system for 20th Century climate, compared to future scenarios for the 2020s, 2040s, and 2080s for the A1B emissions scenario.
Changes in system-wide hydropower production in the Columbia system for three future time frames: large declines in summer, slight increases in winter.
Hamlet et al. 2009 14

15. Agriculture
Given sufficient irrigation, the projected impact of climate change on eastern Washington agriculture is unlikely to be severe. Likely changes in yields from climate alone are increases in winter wheat (2-8% by the 2020s), decreases in irrigated potatoes (15% by the 2040s) and decreases in apples (3% by the 2040s).
However, the combination of warming and elevated CO2 could provide significant potential benefits that offset these declines. There is some uncertainty about whether the CO2 effect is transient, but for well managed crops in eastern WA, the beneficial effect of elevated CO2 will most likely be positive.
Figure 3. Simulated temperature (change, top panel) and precipitation (% change, bottom panel) for the 20th and 21st Century climate model simulations. The black curve for each panel is the weighted average of all models during the 20th Century. The colored areas indicate the range (5th to 95th percentile) for each year in the 21st Century. All changes are relative to averages.
Stöckle et al. 2009 15

16. Salmon and Ecosystems
Rising stream temperature will reduce the quality and quantity of freshwater salmon habitat substantially.
The duration of temperatures causing thermal migration barriers and extreme thermal stress (where weekly water temperatures exceed 70°F) are predicted to quadruple by the 2080s.
Water temperatures for Western Washington stations are generally cooler, and predicted impacts on thermal stress are significant but less severe.
Figure 3. Simulated temperature (change, top panel) and precipitation (% change, bottom panel) for the 20th and 21st Century climate model simulations. The black curve for each panel is the weighted average of all models during the 20th Century. The colored areas indicate the range (5th to 95th percentile) for each year in the 21st Century. All changes are relative to averages.
Mantua et al. 2009 16

17. Salmon and Ecosystems
August Mean Surface Air Temperature and Maximum Stream Temperature
Historical ( )
2040s medium (A1B)
Figure 9. August mean surface air temperature and maximum stream temperature for (top left) and the 2040s (top right, emissions scenario A1B). The area of favorable thermal habitat for salmon declines by the 2040s in western Washington, and in eastern Washington many areas transition from stressful to fatal for salmon.
* Projections are compared with average
Mantua et al. 2009 17

18. Forests
The area burned by fire regionally (in the U.S. Columbia Basin) is projected to double or triple (medium scenario, (A1B)), from about 172,000 ha annually ( ) to 0.3 million ha in the 2020s, 0.5 million ha in the 2040s, and 0.8 million ha in the 2080s.
Due to climatic stress on host trees, mountain pine beetle outbreaks are projected to increase in frequency and cause increased tree mortality. Climatically suitable habitat for pine species susceptible to mountain pine beetle is likely to decline but increase in elevation by the 2040s.
Figure 3. Simulated temperature (change, top panel) and precipitation (% change, bottom panel) for the 20th and 21st Century climate model simulations. The black curve for each panel is the weighted average of all models during the 20th Century. The colored areas indicate the range (5th to 95th percentile) for each year in the 21st Century. All changes are relative to averages.
Littell et al. 2009 18

19. Forests
Figure 11. Changes in areas of potential pine species’ ranges (top panel) and severely water limited forest (bottom panel) in Washington. Areas of orange and yellow in the top panel indicate areas where one or more pines may have difficult re-establishing after disturbance because the climate has exceeded their tolerances (Data: Rehfeldt et al. 2006, multiple IPCC scenarios). Hydrologic modeling suggests many areas on the northern edge of the Columbia basin will become severely water limited (bottom, scenario A1B)
Current
2060s
Changes in the potential climatically suitable range of lodgepole pine
(Data: Rehfeldt et al. 2006, multiple IPCC scenarios).
Littell et al. 2009 19

20. Coasts
A previous study involving the Climate Impacts Group found that sea level rise in Puget Sound might be as little as 6” or as much as 50” by 2100.
Sea Level Rise (SLR) will shift the coastal beaches and increase erosion of unstable bluffs, endangering houses and other structures built near the shore or near the bluff edges.
Shellfish will possibly be negatively impacted by increasing ocean temperatures and acidity, shifts in disease and growth patterns, and more frequent harmful algal blooms (HAB).
Figure 3. Simulated temperature (change, top panel) and precipitation (% change, bottom panel) for the 20th and 21st Century climate model simulations. The black curve for each panel is the weighted average of all models during the 20th Century. The colored areas indicate the range (5th to 95th percentile) for each year in the 21st Century. All changes are relative to averages.
Huppert et al. 2009 20

21. Urban Stormwater Infrastructure
Drainage infrastructure designed using mid-20th century rainfall records may be subject to a future rainfall regime that differs from current design standards. Results from regional climate models suggest increased extreme rainfall in late autumn in western Washington.
Hydrologic modeling of two urban creeks in central Puget Sound suggest overall increases in peak annual discharge over the next half-century, but only those projections resulting from one of the two RCM simulations are statistically significant. Magnitudes of projected changes vary widely, depending on the particular basin under consideration and the choice of the underlying global climate model.
Figure 3. Simulated temperature (change, top panel) and precipitation (% change, bottom panel) for the 20th and 21st Century climate model simulations. The black curve for each panel is the weighted average of all models during the 20th Century. The colored areas indicate the range (5th to 95th percentile) for each year in the 21st Century. All changes are relative to averages.
Rosenberg et al. 2009 21

22. Changes in Flood Risks
Floods in western WA will likely increase in magnitude due to the combined effects of warming and increasingly intense winter storms.
In other parts of the State, changes in flooding are smaller, and in eastern WA projected reductions in flood risk are common due to loss of spring snow cover.
Floods in western WA will likely increase in magnitude due to the combined effects of warming and increasingly intense winter storms.
In other parts of the State, changes in flooding are smaller, and in eastern WA projected reductions in flood risk are common due to loss of spring snow cover.
Mantua et al. 2009

23. Human Health
In Washington, climate change will lead to larger numbers of heat-related deaths due mainly to hotter summers and population growth. For example in Seattle a medium climate change scenario projects 101 additional deaths for people over 45 by 2025 and another 50% increase by 2045
Although better control of air pollution has led to improvements in air quality, warmer temperatures threaten some of the sizeable gains that have been made in recent years.
Figure 3. Simulated temperature (change, top panel) and precipitation (% change, bottom panel) for the 20th and 21st Century climate model simulations. The black curve for each panel is the weighted average of all models during the 20th Century. The colored areas indicate the range (5th to 95th percentile) for each year in the 21st Century. All changes are relative to averages.
Jackson et al. 2009 23

24. Human Health
Figure 14. Percent Increase in Risk of Death, and Number of Deaths Each Day for All Non-Traumatic Causes by Heat Event Duration, Greater Seattle Area, Given 2006 population levels, residents of the greater Seattle area aged 65 and above could be expected to experience, on average, 3 additional deaths on day 1 of a heat event, 10 additional deaths on day 2, and so forth; over a 5 day heat event this age group would incur a total of 45 additional deaths, and during a typical heat event of 2.2 days’ duration, they would incur an additional 14 deaths. Persons aged 85 and above could be expected to experience 25 additional deaths during a 5 day heat event and 9 additional deaths during a typical heat event.
Jackson et al. 2009
Percent Increase in Risk of Death, and Number of Deaths Each Day for All Non-Traumatic Causes by Heat Event Duration, Greater Seattle Area, 24

25. Adaptation Options and Opportunities
Climate change impacts over the next few decades are virtually certain. Impacts beyond this timeframe will be greatly influenced by how successfully we reduce greenhouse gas concentrations both in the near-term and over time.
State and local governments, businesses, and residents are on the “front line” when it comes to dealing with climate change impacts.
Decisions with long-term impacts are being made every day, and today’s choices will shape tomorrow’s vulnerabilities.
Whitely Binder et al. 2009 25

26. Conclusions
Adaptation to climate change impacts is necessary because the projected impacts within and across sectors are large.
To the extent that it can be identified, quantified, and mitigated, uncertainty is a component of planning, not a reason to avoid planning.
Many sectors report different impacts in different systems (e.g., snowpack response at low vs. high elevations, fire response in the western Cascades vs. Blue Mountains, different species of salmonids, different crops etc.), but the natural spatial and temporal complexity of these systems is a key part of planning for the future.
By understanding the direction and magnitude of projected climate changes and their impacts, we can better manage risks and capitalize on opportunities to reduce impacts. 26

27. 27

28. The Climate Impacts Group
JISAO CSES Climate Impacts Group
The Climate Impacts Group
UW Climate Impacts Group
Talk about the climate in the Pacific Northwest and how it has changed over the last years and then how it might continue to change into the future. The purpose is to provide some background and context for the discussions here today surrounding sustainability in water and wastewater industry and minimizing our vulnerabilities in a changing climate.
Climate science in the public interest