1. Climate change impacts and adaptation in the Pacific Northwest
Dennis P. Lettenmaier
Department of Civil and Environmental Engineering
and
Climate Impacts Group
University of Washington
Meeting of the Americas 2008 Joint Assembly
Fort Lauderdale, FL
May 29, 2008

2. Outline of this talk
The UW Climate Impacts Group – the scientific basis
CIG’s role in regional adaptation – Guidebook for local, regional, and state governments
Statewide climate impact assessment
Lessons learned, and evolving issues

3. The Climate Impacts Group
1st of 8 NOAA-funded U.S. Regional Integrated Sciences and Assessment (RISA) teams
UW Climate Impacts Group
Areas of study:
Water resources
Salmon
Forests
Coasts
[Agriculture, Human Health]
Objectives
Increase regional resilience to climate variability and change
Produce science useful to (and used by!) the decision making community

4. Have we seen changes in 20th century climate in the PNW?
UW Climate Impacts Group

5. PNW Temperature Trends by Station
3.6 °F
2.7 °F
1.8 °F
0.9 °F
Cooler Warmer
Mote 2003(a)
Average annual temperature increased +1.5F in the PNW during the 20th century
Annual variability present throughout the warming trend
Almost every station shows warming
Extreme cold conditions have become rarer
Low temperatures rose faster than high temperatures
Temperature increase spread throughout the PNW; in rural areas as well as urban areas.
Each dot represents a station with data going back at least to 1920, size of dot shows magnitude of linear trend. Most trends in the 1-3F range. These data have been quality-controlled and corrected by the National Climate Data Center. This includes removing the “urban warming” effect, which is statistically estimated and is very small.
Small + and – in the figure: denote tiny increases (+) or decreases (-) in temperature on the order of 0.3 degrees C or less
154 stations analyzed for the trends analysis.
Much of the 20th century warming took place in the second half of the 20th century (+ 1.6°F from 1950 to 2000)
Winter warmed 2.7 F (1.3 C) since 1950; approx. 1/3 of the winter warming was due to natural variation in North Pacific climate
In contrast: No clear 20th century trend in precipitation …

6. Trends in Snow Water Equivalent
Decrease Increase
Most PNW stations show a decline in snow water equivalent
Numerous sites in the Cascades with 30% to 60% declines
Decrease Increase
Similar trends seen throughout the western United States - 73% of stations show a decline in April 1 snow water equivalent
Trends in snowpack, like temperature, are very clear.
PNW results based on data from 260 snow course collection sites (Mote 2003)
West-wide results based on 824 snow courses/SNOTEL. Data from NRCS, CA DWR, BC SRM (Figure adapted from Mote, P. W., A. F. Hamlet, M. Clark, and D. P. Lettenmaier Declining mountain snowpack in western North America. Bulletin of the American Meteorological Society 86(1):39-49.)

7. More observed changes in the west
Glaciers are retreating
Peak snowpack is occurring earlier in the year
Mountain snow is melting earlier
Spring streamflow is increasing
Summer streamflow is decreasing
Flood risk has increased in coastal mountain watersheds
Flood risk has decreased in cold, inland watersheds
Lake Washington and Puget Sound have warmed
Snowpack melting earlier: 45 days in low elevation western washington watersheds; 1-2 weeks in higher elevation cascades (date of 90% melt). Hamlet et al
Spring streamflow increasing: trend in March fractional streamflow increasing across west 3-20%. Trend in June fractional streamflow decreasing 3-20% Stewart et al
Flood risk:
November 15,

8. Is This Climate Change?
Are these changes due entirely to natural climate variability? NO
Are these changes due entirely to climate change? NO
…but it would seem to have an increasing influence
The trends are consistent with global climate change projections, and
The trends are generally consistent across the Western U.S.
Re: consistency of trends: trends in snowpack losses are occurring in the very areas where models project losses

9. Projected 21st Century PNW Climate Change
Accelerated warming: °F (~ 0.5ºF average) per decade through at least (compared to 1.5°F over 20th century)
Warming is expected during all seasons with the largest temperature increases likely in summer (June-August)
Precipitation variability continues
High confidence in projected temp changes, less in precipitation changes
2020s
Temperature
Precip
Low
0.7F (0.4C)
- 4%
Average
1.9F (1.1C)
+ 2%
High
3.2F (1.8C)
+ 6%
2040s
Temperature
Precip
Low
1.4F (0.8C)
- 4%
Average
2.9F (1.6C)
+ 2%
High
4.6F (2.6C)
+ 9%
More detail on the new scenarios is available at:
All changes are benchmarked to average temperature and precipitation for

10. Lower Spring Snowpack April 1 Snowpack
Spring snowpack is projected to decline as more winter precipitation falls as rain rather than snow, especially in warmer mid-elevation basins Snowpack will melt earlier with warmer spring temperatures
+4°F, +4.5% winter precip
An underlying message in this slide is that the impacts of warming on snowpack are not equally distributed. Note the projected losses in the Cascades and flanks of the Rockies in Idaho versus projected losses in the Canadian portion of the basin. This has transboundary implications at the state and national level..
Figure 6. Projected changes in April 1 snowpack for the Pacific Northwest. This panel shows the projected loss in April 1 snowpack associated with +4°F warming (likely to occur ~2060s) and a +4.5% increase in average winter precipitation relative to historical ( ) snowpack. The largest declines in April 1 snowpack - up to 100% in many areas - are found in the warmest snow-accumulating locations where warmer temperatures cause more winter precipitation to fall as rain rather than snow. This includes the lower elevations of the Olympics, Cascades, and west slopes of the Rockies. There is little change in the April 1 snowpack in the highest elevation (coldest) locations in the study region. Snowpack is nearly unchanged in the Canadian portion of the upper Columbia Basin. Figure source: Climate Impacts Group3
April 1 Snowpack

11. Projected streamflow changes in the Quinault and Yakima Rivers
Shifts in Streamflow
More winter rain → higher winter streamflows
Warmer temperatures → earlier snowmelt and a shift in the timing of peak runoff
Lower winter snowpack → lower spring and summer flows
Projected streamflow changes in the Quinault and Yakima Rivers
2050s
The black lines in the panels depict simulated average monthly streamflows for the early 20th century for the Quinault and Yakima Rivers, while the gray lines depict the same data for simulated streamflows in the late 20th century. The light blue bands indicate the range of simulated flows for a range of future climate scenarios for the 2040s (+3.6 to +5.4 F). For both river basins, the basic changes include increased winter flows and decreased summer flows as more winter precipitation falls as rain and less accumulates in snow.
+3.6 to +5.4°F
(+2 to +3°C)

12. Impacts of Climate Change on Salmon Recovery in the Snohomish River
Decreasing Spawning Flows
Climate change will make
salmon restoration more difficult:
Decreasing Summer Low Flows
Increasing Winter Peak Flows
Increasing water temperatures in critical periods
Increasing Winter Flows

13. Preparing for Climate Change A Guidebook for Local, Regional, and State Governments
Climate Science in the Public Interest

14. Written to compliment ICLEI’s “Climate Resilient Communities” Program
Motivation for writing grew out of October 2005 King County climate change conference
Written by the CIG and King County, WA in association with ICLEI – Local Governments for Sustainability
Written to compliment ICLEI’s “Climate Resilient Communities” Program
Focused on the process (not a sector), and written for a national audience
Much of what I am discussing today draws from the CIG’s recent guidebook for local governments on preparing for climate change. The purpose here is not to get into the details of what is in the guidebook; I will let the guidebook provide that information to you. Instead, I want to talk in general about the role of local government in adapting to climate change and what adapting to climate change means. 14

15. Planning for Climate Change a.k.a what you will find in the guidebook
Collect and review information on climate change impacts to your region
Build internal and external support for climate change preparedness
Create your preparedness team
Identify your community’s vulnerabilities to climate change
Develop and implement your preparedness plan
Measure your progress and update your plan 15

16. General Implementation Tools
Zoning rules and regulations
Taxation (including tax incentives)
Building codes/design standards
Utility rates/fee setting
Public safety rules and regulations
Issuance of bonds
Infrastructure development
Permitting and enforcement
Best management practices
Outreach and education
Emergency management powers
Partnership building with other communities 16

17. Washington State Climate Impacts Assessment
Provides that, to reduce fossil fuel dependence and build
our clean energy economy, the state should develop policies
and incentives that help businesses, consumers, and farmers
gain greater access to affordable clean fuels and vehicles and
to produce clean fuels in the state. These policies and
incentives should include: (1) Incentives for replacement of
the most polluting diesel engines, especially in school buses;
(2) Transitional incentives for development of the most
promising in-state clean fuels and fuel feedstocks, including
biodiesel crops and ethanol from plant waste;
(3) Reduced fossil fuel consumption by state fleets;
(4) Development of promising new technologies for
displacing petroleum with electricity, such as "plug-in
hybrids"; and
(5) Impact analysis and emission accounting procedures
that prepare Washington to respond and prosper as global
warming impacts occur and as policies and markets to reduce
global warming pollution are developed.
Funding Source: Clean Air/Clean Fuels House Bill 1303
Answers to FAQ regarding HB 1303 from the Washington State Legislature website:

18. Human Health
Infrastructure
Agriculture
Water Resources
A comprehensive state climate change assessment that includes the impacts of global warming
Coasts
Energy
Evaluate Impacts of Climate Change in 2020s, 2040s, 2080s
Use IPCC 2007 Climate Scenarios
Show regional impacts and areas of high and low sensitivity to climate change
Characterize barriers to adaptation to these impacts (e.g., legal, institutional) and prioritize areas for future action
Collaborate with Governor’s Climate Change Challenge Team
To be completed December 2008
Forest Resources
Salmon
Adaptation / Legal Barriers

19. Goals of the Impacts Assessment
Evaluate impacts of climate change into the next century
use IPCC 2007 climate scenarios
show regional impacts and areas of high and low sensitivity to climate change
characterize barriers to adaptation to these impacts (e.g., legal, institutional) with help from UW Law School
provide tools for policy makers and user groups
collaborate with Governor’s Climate Change Challenge team
To be completed December 2008

20. Data Needs to Support a 21st Century Planning Framework Incorporating Climate Information and Uncertainty
Approach provides ensemble of variables that can be used to evaluate impacts of climate change
2 Emissions
Scenarios
20 GCMs 2
Downscaling
Approaches X X
IPCC Climate Scenarios
Precipitation
Air Temperature
Streamflow
Soil Moisture
PET
VPD
And more!
Overall Process for HB1303 Project:
Generally, a range of scenarios of climate change to 2100 are input to a hydrology model that provides projections of streamflow and other hydrologic variables.
-We are utilizing 100 year projections from approximately 20 GCMs, each of which has projections using 2 emissions scenarios. These emissions scenarios, A1B and B1, represent stabilization of CO2 by The B1 scenario is more ecologically friendly than A1B. They generally represent the range of possibly temperature changes into the future.
-The GCM scenarios, which are at a resolution of approximately 3-4 degrees, must be downscaled to the resolution of the hydrology model. We utilize 2 downscaling approaches including a statistical approach and an approach that incorporates results from regional climate models.
The downscaled GCM predictions and resulting hydrologic predictions provide a range of possibilities of future climate change which the various sectors can use to evaluate the impacts in their areas.
Hydrology Modeling

21. Projected Increases in PNW Temperature
14.4°F
Changes relative to
7.2°F
3.6°F
0°F
+2.2ºF ( ºF)
+3.5ºF ( ºF)
+5.9ºF ( ºF) °C
10.8°F
The average warming rate in the Pacific Northwest during the next century is expected to be in the range °C ( °F) per decade, with a best estimate of 0.3°C (0.5°F) per decade. For comparison, observed warming in the second half of the 20th century was approximately 0.2°C (about 0.4°F) per decade. The warming trend for the 20th century overall was 0.15°F per decade. In every scenario, the future warming greatly exceeds natural variability.
Trends in precipitation are less certain. A modest increase (+1-2%) in average annual precipitation is expected through the 2040s, although individual models produce a wide range of results.
Figure: Smoothed traces in temperature for the 39 model simulations, relative to the mean. The smooth curve for each scenario is the Reliability Ensemble Average (REA) value, calculated for each year. The average provided above each box is the REA for that decade; the low and high values represent the lowest and highest value from either scenario (B1 or A1B)
2020s temperature precipitation
low 0.6°C (1.1°F) -9%
average 1.2°C (2.2°F) +1%
high 1.9°C (3.4°F) +12%
2040s temperature precipitation
low 0.9°C (1.6°F) -11%
average 2.0°C (3.5°F) +2%
high 2.9°C (5.2°F) +12%
2080s temperature precipitation
low 1.6°C (2.8°F) -10%
average 3.3°C (5.9°F) +4%
high 5.4°C (9.7°F) +20% 21

22. Hydrology and Water Resources
Reduced snowpack and changes in soil moisture will occur.
Declines in April 1 SWE vary between 35%-41% for the 2040s, depending on the emissions scenario.
There are 40 total greenhouse gas emissions scenarios used to drive global climate models. The 40 scenarios are grouped into four families: A1, A2, B1, and B2. The CIG is using the B1 and A1B scenarios for the HB 1303 work.
The B1 emissions scenario represents a slower increase in greenhouse gas emissions with stabilization of CO2 concentrations by 2100 (the concentration of carbon dioxide will be 550ppm in 2100). The A1B emissions scenario has higher greenhouse gas emissions than the B1 scenario: the concentration of carbon dioxide will be 720ppm in 2100.
The A1B and B1 scenarios have the same population projections (population peaking mid-century then declining). The main difference in the scenarios is energy use. The A1B scenario story line has a balance between fossil fuels and other energy sources, while the B1 story line assumes the use of more clean and resource-efficient technologies. 22

23. Coasts 3” 6”
30”
50”
2050
2100
13”
40”
20”
10”
Rising sea levels will increase the risk of flooding, erosion, and habitat loss along much of Washington’s 2,500 miles of coastline.
Medium estimates of SLR for 2100: +2” for the NW Olympic Peninsula +11” for the central/southern coast +13” for Puget Sound Higher estimates (up to 4 feet in Puget Sound) cannot be ruled out.
Episodic flooding will likely pose a greater risk than permanent inundation of low-lying areas from increases in mean sea level.
Lower amounts of local SLR will be apparent on the northwest Olympic Peninsula given rates of local tectonic uplift that currently exceed projected rates of global SLR. SLR estimates for the central and southern Washington coast are more uncertain. Available (but limited) data suggests that uplift is occurring in this region, but at rates lower than observed on the northwest Olympic Peninsula. The 6” and 13” marks on the figure are the SLR projections for the Puget Sound region and effectively also for the central and southern WA coast (the rates are nearly identical for the central and southern coast: +5 inches by 2050 and +11 inches by 2100)
Assumptions of continued rapid ice melt from Greenland and Antarctica are a major factor in the potential for higher amounts of SLR. 23

24. Projected Maximum Weekly Average Water Temperatures – 2040s
Salmon
Water temperature is already a problem in many WA stream reaches.
Exceedances of WQ criteria for temp, especially in summer, will increase with warmer summer temperatures and reduced low flows due to earlier snowmelt.
Projected Maximum Weekly Average Water Temperatures – 2040s
From the interim report:
In the period, 15% of the stations included in our analysis had an observed maximum weekly average water temperature greater than the 21ºC (70°F) water quality criteria, and all of those stations are located in the interior Columbia Basin. Under the A1B emissions scenario, 2040s August average air temperatures are projected to rise by 2.8ºC (approximately 5.0°F). Using the delta method by assuming an equivalent rise in the annual maximum weekly water temperature results in 49% of these stations exceeding the 21ºC (70°F) criteria, with many recording stations in southwest Washington and the Puget Sound Lowlands and all the stations in the Columbia Basin exceeding the 21ºC (70°F) criteria. Although this approach ignores a range of factors that give rise to the observed heterogeneity in stream temperatures, this simple projection should give a useful preview of the projected stream temperatures we will develop in the next year using the 1/16 degree gridded air temperature fields and empirically-based stream temperature models.
The period of maximum temperatures will vary from stream to stream, therefore this figure is generally for summer temperatures and is not tied to a specific month (although most occurred in September). How were these values calculated? We took the average weekly maximum water temperature at each station for and averaged those max temps at each site. Changes are calculated from this base period.
49% of stations exceed the 21ºC (70°F) water quality criteria (changes relative to ) 24

25. Lessons learned, and evolving issues
Finding the happy medium between top down and bottom up management
The need for a strong core research staff
The need for strong core financial support
Fostering links between social and natural sciences
Managing outreach