1. Dirty Little Secrets of the Greatest Snow on Earth and the Future of the Great Salt Lake Jim Steenburgh Department of Atmospheric Sciences University of Utah Jim.Steenburgh@utah.edu Contributors: Tom Painter, Trevor Alcott, John Horel, Thomas Reichler, Leigh Jones, Chris Landry, Jeff Deems, Annie Bryant, McKenzie Skiles, Ashley Powell, Jayne Belnap, Mark Miller, Jason Wolf, and many more...

2. Prediction is very difficult, especially about the future - Danish Physicist Niels Bohr Words of Wisdom And more so the Great Salt Lake - Jim Steenburgh

3. 5/13/20153 Global Temperature Change Earth’s average surface temperature has increased 1.4°F since 1900 Earth’s average surface temperature has increased 1.4°F since 1900 Source: Climatic Research Unit, University of East Anglia

4. Utah Temperature Change Last decade 2°F warmer than 100 year average Last decade 2°F warmer than 100 year average –Warming trend larger than global average trend Frequency of “warm” years increasing Frequency of “warm” years increasing Frequency of “cold” years decreasing Frequency of “cold” years decreasing Mother nature playing with loaded dice Mother nature playing with loaded dice 1993 2008

5. Utah Mountain Snowpack No clear linkage between global warming and long-term (75+ year) trends in Utah’s upper-elevation mountain snowpack No clear linkage between global warming and long-term (75+ year) trends in Utah’s upper-elevation mountain snowpack Recent fluctuations are within range of past variability Recent fluctuations are within range of past variability Graph uncorrected and does not include 2006-2010 Graph uncorrected and does not include 2006-2010 Courtesy: Randy Julander, NRCS

6. Streamflow & Lake Level Decadal-scale variability continues to dominate lake levels Decadal-scale variability continues to dominate lake levels Lake levels currently low, but remain with range of past variability Lake levels currently low, but remain with range of past variability Linkages between recent fluctuations and warming remain unclear Linkages between recent fluctuations and warming remain unclear GSLB Hydrologic Observatory Prospectus

7. Key Points: Recent Climate Change Earth is warming Earth is warming –Utah warming faster than global average, but with more variability Temperature dice are “loaded” Temperature dice are “loaded” –Odds of warm seasons and years increasing –Odds of cold seasons and years decreasing Year-to-year and decadal variability still dominate Utah snowpack and GSL level fluctuations Year-to-year and decadal variability still dominate Utah snowpack and GSL level fluctuations –Unclear if snowpack and GSL dice are loaded yet 7 Casinosupply.com

8. The Future We are confident about warming but We are confident about warming but –How fast will it warm? –How sensitive is Utah snowfall & runoff to warming? –Will the storm tracks & lake-effect change? –What about variability/extremes?  More big years? More droughts? –What about climate feedbacks, surprises, and dirty little secrets? –What does this mean for the GSL?

9. 9 Unique local climate – transition zone Unique local climate – transition zone Modeling precipitation very challenging Modeling precipitation very challenging –Complex terrain/lake effects Utah Climate Prediction Challenges Warren Washington, NCAR Have this: 60x90 miles Want this: Reality

10. Alta Base Mt. Baldy PC Base PC Top Wasatch Snowfall Sensitivity +1°C +2°C +3°C +4°C 10% 20% 30% 40% 50% Courtesy: John Horel and Leigh Jones, Univ. of Utah Percent of snow that will instead fall as rain with warming Alta Base Mt. Baldy PC Base PC Top Alta Base Mt. Baldy PC Base PC Top Alta Base Mt. Baldy PC Base PC Top

11. Alta Base Mt. Baldy PC Base PC Top Temperature Change by 2050 1980-1999 Nov-Apr 2040-2059 °C A1B, 1980-1999 vs. 2040-2059 SLC 3°C 38 ° F St. George 8°C 46 ° F SLC 5°C 41 ° F St. George 10°C 50 ° F Courtesy Thomas Reichler Univ. of Utah +2°C 10% 20% 30% 40% 50%

12. Range of Possibilities Northern Utah Winter (Nov-Apr) Temperature Change Relative to 1980-1999 2100 CO2 = 2.5x Pre-Industrial (~700 ppm) +3°C +1°C 6 2 4 0 -2 Temperature Change °C 2000 2020 2040 2060 2080 Alta Base Mt. Baldy PC Base PC Top Alta Base Mt. Baldy PC Base PC Top

13. Precipitation Changes You Are Here

14. Average Winter Precip Change A1B, 2040-2059 minus 1980-1999 Absolute Relative Nov-Apr % No Change 12% Increase mm No Change 5” more Courtesy Thomas Reichler Univ. of Utah

15. Snow Optics Lab-Alta Site (SOLA) 30 April, 2009 Dirty Climate Secrets & Thinking beyond CO 2 Courtesy Tom Painter

16. Sevier Lake Milford Flat Fire DustPlumes Courtesy Tom Painter

17. The Intermountain Haboob

18. Impact of Dust: A Perfect Storm Dust decreases snow albedo (reflectivity) Dust deposition comes generally in the spring (Neff et al, 2005) - solar irradiance is increasing - snowpack is warming Dust generally accumulates in surface layers and is not entrained in melt - therefore, the surface continues to darken April, 2009May, 2009 Rabbit Ears Pass, Colorado 43 ppmw 52 ppmw 306 ppmw 406 ppmw Courtesy Tom Painter

19. Changes in dust loading Post-disturbance ------------------------1850AD Pre-disturbance Neff et al (2008), Nature Geosciences

20. High Wind + Vulnerable Soils = Dust Storms Biological crusts: occur on all soils, but easily crushed Rocks: cover low in many places Plants: rainfall timing, temperatures critical Physical crusts: do not occur on sandy soils, easily crushed

22. Senator Beck Basin Study Area Courtesy Tom Painter

23. Concluding Thoughts Trends expected to emerge during the 21 st century include Trends expected to emerge during the 21 st century include –Reduced snowfall and snowpack in low-to-mid elevation mountain areas  Upper elevation trends less clear –Earlier and less intense spring runoff –Increased demand for residential and agricultural irrigation –Lower average GSL levels and increased salinity How quickly these trends dominate local climate variability remains an important area of research How quickly these trends dominate local climate variability remains an important area of research –Natural variability in the GSL system is very large and needs to be better understood –There is more to the story than GHG related warming A comprehensive observing and modeling system is needed for the Great Salt Lake Basin A comprehensive observing and modeling system is needed for the Great Salt Lake Basin

24. Snowfall Sensitivity: Snowbird Courtesy: John Horel and Leigh Jones, Univ. of Utah Snowfall decrease (%) per Dec C at 9650 ft

25. Concluding Thoughts Future warming is already in the pipeline Future warming is already in the pipeline –Climate inertia –Socio-economic inertia Efforts to reduce CO 2 emissions will only have an impact after ~2040 Efforts to reduce CO 2 emissions will only have an impact after ~2040 New modeling systems are needed to improve our understanding and prediction of the GSL basin New modeling systems are needed to improve our understanding and prediction of the GSL basin –Need to consider decadal-scale prediction in addition to long- term trends –Must think beyond CO2  Consider regional climate change as a multifaceted problem

26. 0 The Trend? 10 5 Precipitation Change (in) 5 2000 2020 2040 2060 2080 Courtesy Thomas Reichler Univ. of Utah Northern Utah Winter (Nov-Apr) Precipitation Change Relative to 1980-1999 2100 CO2 = 2.5x Pre-Industrial (~700 ppm) Slight Loading of Dice for “Wet” Winters But Is the Storm Track Right? No Lake-Effect