The Rocky Mountains: Climate Change—Past, Present, FutureA Warmer West A Warmer Colorado Colorado Temperature Trends Slide Number 5Slide Number 6Slide Number 7North-Central ColoradoNorth-central Colorado subalpine zone* Slide Number 10Slide Number 11Slide Number 12Slide Number 13Moisture Deficits (C1) – Thornthwaite method (more later when we discuss tree mortality and climate)Slide Number 15Slide Number 16Slide Number 17Slide Number 18Slide Number 19Brief Introduction to Reconstruction of Climate from Tree RingsSlide Number 21Slide Number 22Slide Number 23Slide Number 24Slide Number 25Slide Number 26Slide Number 27Slide Number 28Slide Number 29Slide Number 30Slide Number 31Slide Number 32Slide Number 33Slide Number 34Slide Number 35Slide Number 36Slide Number 37Slide Number 38Slide Number 39Slide Number 40Slide Number 41Slide Number 42Slide Number 43Slide Number 44Slide Number 45Slide Number 46Slide Number 47Slide Number 48Slide Number 49Slide Number 50Reconstructed Blue River Annual Streamflow, ColoradoReconstructed Temperatures from Multiple Proxies, the famous “Hockey Stick” graphClimate Modes and Major OscillationsClimate Modes (“oscillations”) That Explain Global Climate Variability at Annual to Centennial Time ScalesGlobal Circulation PatternsSlide Number 561. Northern Annular Mode (NAM)2. Pacific North American Pattern (PNA)El Nino-Southern OscillationSlide Number 60ENSO affects subtropical highs and jet streams determining storm tracks and weather across North AmericaTree-ring reconstructions of climate modesThe Rocky Mountains: Climate Change—Past, Present, Future• The instrumental climate record• Brief introduction to reconstruction of climate from tree ringsA Warmer West• Rocky Mountain Climate Organization (Saunders et. al. 2008)– The West is warming more than any other part of the US (excluding Alaska)–Colorado average temperature has increased over 3 deg F over the past 100 years – with almost 2 degrees in the past 5 years.(Saunders et. al. 2008)A Warmer Colorado(Ray et. al. 2008)Trend LinesBlue - 100 yearRed - 50 yearOrange - 30 yearSignificant 97.5%Daily Average Temperatures (F), Annually AveragedColorado Temperature Trends Klaus Wolter (6 dec ‘06)NOAA-ESRL, and University of Colorado, CIRES Boulder(in collaboration with Nolan Doesken, State Climatologist, CSU)Regionalization and seasonalizationNorth-Central ColoradoBest stations:Steamboat SpringsWaldenHaydenSpicerGrand LakeNorth-central Colorado subalpine zone* * Climate Division 102: Grand Lake, Hayden, Spicer, Steamboat Springs, WaldenMaximum spring temperature + 2.6oC since 1955+ 2.6oCFrom: K. Wolter,NOAA-CIRES 2006Increasing minimum and maximum temperatures in all seasons in N-C ColoWinterSummerFallSpringVeblen Permanent Plots (>5000 trees)6 old-growth:wet MRS 5BL 6MRS4BW 3BW 2dry MRS 74 post-fire lodgepole:MRS 1MRS 8MRS 9MRS 1030 gap:@ MRS 1@ MRS 4@ BL 6C1Eastern Slope Subalpine Zone: Niwot Ridge C1 (J. Smith in progress)minmaxMaxMaxMinMinC1 - ClimateSeasonal precipitation is highly variable. C1 data shows a slight decrease (>10 cm) in winter and summer average precipitation in the last 10 years when compared to the previous 45 years.Roughly a 2 deg rise in average maximum temperature for both spring and summer in the last 10 years when compared to the previous 45 years.Moisture Deficits (C1) – Thornthwaite method(more later when we discuss tree mortality and climate)mean deficit 1982 – 1994 = 41.88 mmmean deficit 1995 – 2007 = 65.27 mmBaron et al. 2009.Global Change Biol. 15:1777-89Loch ValeTemperatures1991-2006(Baron et al.2009)Fraser Experimental Forest: Hourly Temperature Record 1976-2003(K. Malm 2009)Fraser Experimental Forest: Hourly Temperature Record 1976-2003Consensus on Climate Variation in the U.S. West(IPCC 2007, U.S. Clim Change Sci. Program Synthesis, 2008, Hoerling and Eisched 2008)Warming TrendWarming is causing a shorter snow accumulation period; early snow melt.Continued Natural Variability in PrecipitationGCMs do not predict major changes in precipitation in the Colorado RockiesTree-ring records of longer and more severe droughts (e.g. 16thcentury mega-drought) than recent droughtsNatural variability in ocean surface temperatures is likely to continue to be the major driver of precipitation variabilityGlobal Change Type Droughts: Warming + Natural Variability = > Ecological ImpactGreater impact of the 1998 drought in the SW than the 1950s drought (Breshears et al. 2005)Brief Introduction to Reconstruction of Climate from Tree Rings• H. Fritts. 1976. Tree Rings and Climate. Acad. Press• Fritts, H.C. and T.W. Swetnam. 1986. Dendroecology: A tool for evaluating variations in past and present forest environments. Hunton and Williams, Washington, D.C. (and Adv. Ecol. Res. 1989)• H. Grissino-Mayer’s Ultimate Tree-Ring Page http://web.utk.edu/~grissino/ excellent source of figures explaining tree-ring applicationsBarkEarlywood vs.latewoodPrinciple of Limiting FactorsNarrow rings due to lack of moisture: common in relatively dry Colorado forestsPrinciple of Site Selection• Within any given area chosen for study, specific site characteristics should be sought that will enhance a tree’s responsiveness to environmental factors.• Notice how this is related to the principle of limiting factors. We should select sites where factors are more limiting.• Notice also that recognizing the growth forms of trees will provide clues where such sensitive sites exist.What to look for in trees that indicate longevity:1. Dead spike top or broken top2. Heavy, drooping lower limbs3. Short stature, inverted carrots4. Erratic growth forms5. Stripbark6. Sparse foliage in crown7. Exposed roots8. Isolated individualsEl Malpais National Monument, NMCrossdatingOverview: Linear Aggregate Tree Growth• Tree growth can be “decomposed” into five basic parts:R = ring width, t = the current year, and delta = presence (1) or absence (0) indicator1. A = age-related trend2. C = climate3. D1 = exogenous (external) disturbance processes (examples?)4. D2 = endogenous (internal) disturbance processes (examples?)5. E = random errorThree well dated and measured tree-ring samples.CrossdatingStandardizationAge trendClimateSeparating age trend vs. climate influences• For dendroclimatic reconstruction you can not use raw measurements because…• Normal age-related trend exists in all tree-ring data = negative exponential or negative slope.• Some trees simply grow