Philip Mote, Lara Whitely BinderPhilip Mote, Lara Whitely BinderClimate Impacts GroupCenter for Science in the Earth SystemJoint Institute for the Study of the Atmosphere and OceanUniversity of WashingtonATMS 211 May 23, 2007http://www.yakima.net/UW Climate Impacts GroupUW Climate Impacts GroupClimate science in the public interestUW Climate Impacts GroupClimate Change in the Climate Change in the Pacific NorthwestPacific NorthwestImpacts, Choices, and ChangeImpacts, Choices, and ChangeAreas 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 community1st of 8 U.S. Regional Integrated Sciences and Assessment (RISA) teams UW Climate Impacts GroupThe Climate Impacts GroupKey Trends in 20Key Trends in 20ththCentury ClimateCentury ClimateAverage annual temperature increased +1.5°F in the PNW during the 20th century3.6 °F2.7 °F1.8 °F0.9 °FCooler WarmerMote 2003(a), updatedTemperature Trends (°F per century), since 1920Key Trends in 20Key Trends in 20ththCentury ClimateCentury ClimateAverage annual temperature increased +1.5°F in the PNW during the 20th centuryApril 1 snowpack has decreased throughout the PNW with losses of 30-60% at many individual stations (1950-2000)Decrease IncreaseNearly every glacier in the Cascades and Olympics has retreated during the past 50-150 yearsPhotos courtesy of Dr. Ed Josberger, USGS Glacier Group, Tacoma, WASouth Cascade Glacier, 1928 (top) and 2000 (right)Trends in Spring RunoffTrends in Spring RunoffStewart et al. J Climate 2005 Peak of spring runoff is moving earlier into the spring throughout western U.S. and Canada-3-2-1012341916192019241928193219361940194419481952195619601964196819721976198019841988199219962000Std Anomalies Relative to 1961-1990PNWCACRBGBRegionally Averaged Cool Season (Oct-Mar) Precipitation AnomaliesAnd What About Trends in Precipitation?...And What About Trends in Precipitation?...Little evidence of a consistent trend in the PNW but coherence and variability seem to have increased noticeably throughout the West around 1973Is This Human-induced Climate Change?• Are these changes attributable entirely to greenhouse gases?NO• Are these changes attributable entirely to natural climate variability? NO…but a climate change signal may be emergingQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.And what about the PNW in the 21st century?UW Climate Impacts GroupProjected 21Projected 21ststCentury PNW WarmingCentury PNW Warming+1.9ºF (0.7-3.2ºF)+2.9ºF (1.4-4.6ºF)More detail on the CIG scenarios is available at: http://www.cses.washington.edu/cig/fpt/ccscenarios.shtml • Mean change: +2°F (2020s), +3°F (2040s) • Rate of change expected to be 3x greater• Warming expected in all seasonsChanges relative to 1970-1999• Modest increases (+2%) in annual average precipitation• Most of the increase comes in the winter months (but in what intensity?)• Projected increase in average does not exceed range of 20thcentury averagesProjected changes in monthly PNW precipitation. The lines show changes associated with warm (IPSL-A2), cool (GISS-B1), and “middle-of-the-road” (ECHAM5-A2) climate change scenariosProjected Changes in PNW PrecipitationProjected Changes in PNW PrecipitationNote: there is high confidence in projected temp changes, less in precipitation changesChanges Relative to the 20Changes Relative to the 20ththCenturyCentury2080sSpring snowpack is projected to decline as more winter precipitation falls as rain rather than snow, especially in warmer mid-elevation basinsSnowpack will melt earlier with warmer spring temperaturesLower Spring SnowpackLower Spring Snowpack+4°F, +4.5% winter precipApril 1 SnowpackStreamflow ImpactsStreamflow ImpactsHigher winter streamflowsEarlier and lower peak runoff (mid/high basins)Lower late spring streamflowLower, warmer summer streamflows~2050s to 2080s~2050s to 2080sProjected streamflow changes in the Quinalt and Yakima Rivers+3.6 (~2050s) to +5.4°F (~2080s)~2050s to 2080s~2050s to 2080sImplications for Water ManagementImplications for Water Management• Increased demand among competing uses (M&I, habitat, irrigation, water quality navigation, recreation, hydropower)• Increased risk of winter flooding in many basins (changes in urban flooding less clear)• Water systems must manage longer and more extreme drawdown periods that in the past• Bottom line: Increased competition for water and increased vulnerability to droughtEarly peak flowsFloods??Warm, lowstreamflow Salmon Impacted Across Full LifeSalmon Impacted Across Full Life--CycleCycleClimatic Change and Tree Growth ResponsesClimatic Change and Tree Growth ResponsesSubalpine forestsSea levelWestern Cascades ForestsLow elevation forestsMid elevation forests(Maritime Climate) (Continental Climate)Eastern Cascades ForestsOlympic ForestsSubalpine forests:longer, warmer growing seasons, shorter snowpack duration = growth increase Mid elevation forests: warmer summers, lower snow pack = growth depends on precipitation changeLow elevation forests:warmer summers, potentially less summer precipitation = large growth decrease(Max. ~ 8000 ft.)(Max. ~ 8000 ft.)• Increased vulnerability to fires and insect outbreaks due to a longer dry season (except in especially cool-wet locations)– BC outbreak of the mountain pine beetle has killed 100 billion board feet– Lack of extreme cold, killing temperatures and current forest practices has allowed the beetle to thrive in epidemic numbersbeetle killed pines in BCBeetle photos from http://www.for.gov.bc.calFire and InsectsFire and Insects• Relative sea level rise may be greatest in South Puget Sound (~3ft by 2100) and least near Neah Bay (~1ft by 2100)• Likely to increase pace and extent of erosion and nearshore habitat lossSea Level Rise ScenariosSea Level Rise and Plate TectonicsMarine and Ecosystem FunctionMarine and Ecosystem Function• Climate change likely to impact several key parameters, e.g. water temperature, salinity, stratification, dissolved oxygen, nutrient availability (direction/magnitude of impact varies with parameter, location, time of year)• Climate change will affect the Puget Sound ecosystem from the bottom-up (e.g., via impacts to phytoplankton) and top-down (e.g., via impacts to salmon, marine mammals)• The ultimate impact of