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SLIDE 1

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SLIDE 2

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SLIDE 3

The “Greenhouse Effect”

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SLIDE 4

CO2 etc.

GLOBAL CLIMATE

Earth’s Orbit & Tilt Dust Aerosols Ash Solar Output

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SLIDE 5

CO2

GLOBAL CLIMATE

Earth’s Orbit & Tilt Dust Aerosols Ash Solar Output ~+2.5 watts per m2

(and growing)

~+0.06 to +0.1 watts per m2 since 1750 due only to amplification of 11 year cycle

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SLIDE 6

Ice cores and other archives give us information on past climate and CO2

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SLIDE 7

2000 Years of GHG Change!

Source: IPCC 2007

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SLIDE 8

Recent GHG Change!

Source: NASA

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SLIDE 9

Historic Observed Changes: A Global Context

!!2012 9th Warmest Year !!2010 Warmest Year on Record

  • NASA GIS, 2012 Data

!!2012 Hottest Year in US history

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SLIDE 10

http://earthobservatory.nasa.gov/IOTD/view.php?id=77671

Record Breaking Summer Ice Retreat

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SLIDE 11
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SLIDE 12

Arctic Amplification: Implications for mid-latitudes as well

  • NASA GIS, 2013 Data

!! Global: 0.6°C (1.1°F) since 1950 !! Arctic Region: 2.0°C since 1950

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SLIDE 13

http://earthobservatory.nasa.gov/

Historic High Temperatures

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SLIDE 14

March 2011 March 2012

http://earthobservatory.nasa.gov/

Drive Low Spring Snowpack

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SLIDE 15

Recent Changes Across the Western U.S. & Region

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SLIDE 16

!! Minimum Temperatures have warmed faster than maximums !! Greatest warming in the Northern Rockies. !! Strong GHG signal

  • Bonfils et al. 2009 J Clim

Recent Warming: 1950-2000

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SLIDE 17

Trends in APRIL 1 snow pack: 1950-2000

From Mote et al. 2006

Percent change since 1950 Absolute change since 1950

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SLIDE 18

Trends in Snowmelt Timing

Stewart et al. 2005 J Climate!

  • ! 302 gauges
  • ! trend:1948-2002
  • ! center of mass of spring

pulse

  • !1-4 week advance

in pulse

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SLIDE 19

More Rain and Less Snow

Knowles et al. 2006 J Climate!

  • ! Trend:1949-2002
  • ! Fractional change in winter SFWE

after removing effects of trends in precipitation

  • !75% of stations experienced

snowfall reductions as a result of warming

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SLIDE 20

Temperature " = Snow# & Streamflow #

  • -Barnett et al. 2008, Science!

30 to 60% of declines caused by GHG enhanced warming

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SLIDE 21

Projected Impacts of Increasing Evaporation & Earlier Snowmelt Diminished winter flows with greater chance of floods Earlier peak with variable impacts on magnitude

  • f peak flow

Greatest impacts in late-summer

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SLIDE 22

US Forest Service lands National Park Service lands Glaciers

“Glaciers” in the American West 1 : 24,000 3079 141 1 1475 1778 1158 463

8303 permanent snow and ice bodies

688 km2

450 4.8 73.3 68.6 46.2 42.5 0.09 208 2.6

Andrew G. Fountain

  • Moore et al. 2008
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SLIDE 23

US Forest Service lands National Park Service lands Glaciers

Fraction of Glacier Area Lost since 1900

66%

24%

30%

56% 40%

31%

42%

25%

46%

  • Fountain et al, 2007
  • Moore et al. 2008
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SLIDE 24

1910

Morton Elrod photo Courtesy of GNP Archives

2007

Pederson & Fagre photo USGS

Boulder Glacier

Glacier National Park, MT

20th Century Retreat

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SLIDE 25

Sperry Glacier

1913

Alden, USGS

2005

  • K. Holzer, USGS
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SLIDE 26

Grasshopper Glacier and middle branch of Glacier in 1898 photographed by Anders Wilse Wilse Glacier (far left), Middle Wilse Glacier, and Grasshopper Glacier in 2001

  • E. Chatelain
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SLIDE 27

Yellowstone Region Snow and Streamflow Histories

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SLIDE 28

Science, 9 June 2011: [DOI:10.1126/science.1201570]

The unusual nature of recent snowpack declines in the North American Cordillera

Gregory T. Pederson1,2

, Stephen T Gray3, Connie A Woodhouse2,

Julio L. Betancourt, Daniel B. Fagre1, Jeremy Littell4, Brian Luckman5, Emma Watson, and Lisa J. Graumlich2

  • 1. U.S. Geological Survey
  • 2. University of Arizona
  • 3. University of Wyoming
  • 4. University of Washington
  • 5. University of Western Ontario
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SLIDE 29

Primary Data

Major River Headwaters !! Colorado River Headwaters !! Yellowstone / Missouri River Headwaters !! Columbia River Headwaters Data: !! USGS Hydrologic Units !! NRCS Snow Course Records !! ITRDB, personal, and collaborators moisture sensitive tree-ring chronologies

1544 m 2307 m 2807 m

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SLIDE 30

Subalpine Larch"

  • Pederson Photo
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SLIDE 31
  • Littell Photo
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SLIDE 32

Mountain Hemlock"

  • Littell Photo
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SLIDE 33

Results: Calibration

  • Pederson et al, Science, 2011
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SLIDE 34
  • 2. Spring Warming &

Precipitation account for remaining variation in Peak SWE & Streamflow

  • 1. Ocean-Atmosphere

teleconnections drive Peak SWE & Streamflow

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SLIDE 35

LIA MCA

  • Pederson et al, Science, 2011
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SLIDE 36
  • Pederson et al, Science, 2011

To contextualize 100% of 1981-2010 mean SWE conditions… …we have reached average snow conditions for a period

  • f record LOW snowpack

compared to conditions of the past 800 years…

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SLIDE 37

The current conditions maps should look more like this…

Synchronized Western Snowpack Declines

Meaning…

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SLIDE 38

So how can we be sure warming temperatures play a major role in west-wide snow declines? Test the idea with a Snow Model

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SLIDE 39

Snow Model: Temperature Relationship

  • Pederson, Betancourt and McCabe, GRL, 2013
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SLIDE 40

Post-1980s Synchronous Snowpack Declines

  • Pederson, Betancourt and McCabe, GRL, 2013
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SLIDE 41

20% Decline in Snowcover

  • Pederson, Betancourt and McCabe, GRL, 2013
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SLIDE 42

Implications

  • ! The post-1980s synchronous snowpack declines

may be the inflection point for a new era of non- stationarity in Western water resources

  • ! The last few decades may in fact signal a

fundamental shift from precipitation (i.e. stormtrack) to temperature as the dominant influence on snowpack in the North American Cordillera

  • ! Increased warming will likely continue to modify the

annual hydrograph and stream temperatures altering aquatic habitats and challenging water resource managers

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SLIDE 43

Western US River Sensitivity Study

Gray and McCabe, WRR 2010

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SLIDE 44

Yellowstone River Sensitivity Study

Gray and McCabe, WRR 2010

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SLIDE 45

Yellowstone @ Corwin Springs

Upper Yellowstone River

  • !Headwaters above Corwin

Springs, Montana

  • !Drains approx. 6794 km2
  • !Majority in Yellowstone

National Park

  • !Unregulated flows
  • !Gage in continuous operation

since 1911

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SLIDE 46

Water Balance Estimates of Yellowstone River Runoff

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SLIDE 47

Baseline Scenario: Tree-ring Precip & Temperatures from Climatology

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SLIDE 48

Average Long-term Runoff: All Scenarios

10-14% Decline

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SLIDE 49

Average Runoff: Driest 10th percentile

Additional 17-24% Decline

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SLIDE 50

Scenario Comparison: 25-year Moving Averages

Baseline 2025 2050 2100

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SLIDE 51

Yellowstone Region Climate Projections:

And what we don’t know…

  • aka. Uncertainties…

a bad word I’ve been told…

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SLIDE 52

Prepared by the UW Climate Impacts Group – http://cses.washington.edu/cig/

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SLIDE 53

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SLIDE 54

D4(E.95.,%!#75%9.+564<%9:*+/.7%0+%&CH%=+(>3*9?%

Projections for 2040s: Average 34% decline

Prepared by the UW Climate Impacts Group – http://cses.washington.edu/cig/

warm, wet winters 10 model average Very warm & wet winters

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SLIDE 55

D4(E.95.,%!#75%9.+564<%9:*+/.7%0+%&CH%=(0'%I(07564.%

Projections for 2040s

Prepared by the UW Climate Impacts Group – http://cses.washington.edu/cig/

warm, wet summers 10 model average Very warm & dry summers

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SLIDE 56

D4(E.95.,%!#75%9.+564<%9:*+/.7%0+%&CH%=622.4%84(6/:5%

Projections for 2040s

Prepared by the UW Climate Impacts Group – http://cses.washington.edu/cig/

warm, wet summers 10 model average Very warm & dry summers

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SLIDE 57

So yes the West will dry because of this… But, we have real trouble saying where and how fast the West will dry because of errors associated with this…

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SLIDE 58

We tend to think of future climate change as a simple linear trend…

What do we know?

Future Climate = Natural Variability + Warming

Gray et al. (2006), Ecology 87:1124-1130

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SLIDE 59

We tend to think of future climate change as a simple linear trend… Future climate will be a combination of human-induced trends and natural variability

Gray et al. (2006), Ecology 87:1124-1130

What do we know?

Future Climate = Natural Variability + Warming

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SLIDE 60

We tend to think of future climate change as a simple linear trend… Future climate will be a combination of human-induced trends and natural variability

Gray et al. (2006), Ecology 87:1124-1130

What do we know?

Future Climate = Natural Variability + Warming

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SLIDE 61

Questions?

Greg Pederson: Email: gpederson@usgs.gov