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 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...

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

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

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

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 Graph uncorrected and does not include Courtesy: Randy Julander, NRCS

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

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

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 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

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

Alta Base Mt. Baldy PC Base PC Top Temperature Change by Nov-Apr °C A1B, vs 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%

Range of Possibilities Northern Utah Winter (Nov-Apr) Temperature Change Relative to CO2 = 2.5x Pre-Industrial (~700 ppm) +3°C +1°C Temperature Change °C Alta Base Mt. Baldy PC Base PC Top Alta Base Mt. Baldy PC Base PC Top

Precipitation Changes You Are Here

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

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

Sevier Lake Milford Flat Fire DustPlumes Courtesy Tom Painter

The Intermountain Haboob

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

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

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

Senator Beck Basin Study Area Courtesy Tom Painter

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

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

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

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