1. Estimating Potential Impacts of Climate Change on the Park City Ski Area Brian Lazar Stratus Consulting Inc. Blazar@stratusconsulting.com Mark Williams University of Colorado Institute of Arctic and Alpine Research Markw@snobear.colorado.edu

2. Objective: Evaluate Future Changes in Climate  Park City Ski Area  Years  2030  2075  2100  Climate  Air temperature  Precipitation

3. Climate Analysis Approach Emission scenarios - IPCC Climate response modeling - General circulation models (GCMs) - Regional climate models (RCMs) Scale to Park City - MAGICC/SCENGEN - Statistical downscaling - Dynamic downscaling Estimate effects on snow - SRM - Snow depth

4. Climate Change  “Climate change” refers broadly to any changes in climate (air temp, precip)  Here we focus on potential climate change caused by human emissions of greenhouse gases (GHG)  Carbon dioxide  Nitrous oxide  Methane

5. Recent Changes in Climate in the Park City Region

6. U.S. Air Temperatures Have Increased over the 20th Century  Warming in the US is concentrated in the mountain areas of the west.  The western US has warmed about 2°F in the last five years compared to the last 100 years. Source: Dr. Martin Hoerling, NOAA, Boulder, CO.

7. ALTA: Annual air temperatures (1970-2006)  Max air temperatures show no trend  Min temperatures are increasing about 0.8°F/decade

8. Summary of Annual Air Temperature Trends in the Park City Region 1.All weather stations show a warming trend for daily minimum temperatures (ranging from 0.05° to 1.6°F/decade) 2.No trend in daily maximum temperatures 3.Troubling: snowmaking depends on cold night- time air temperatures

9. Rising CO 2 Will Lead to Accelerated Rise in Air Temperature

10. Different Climate Scenarios  Three CO 2 warming scenarios  Business as usual (AIB)  Green scenario (BI)  Worst-case scenario (AIF1)  Three different years for each CO 2 scenario  2030: normal business projection  2070: threshold for large effects?  2100: long-term

11. 5 x 5° Grid Boxes Near Park City  300 miles on a side  RCM box 20 miles on a side

12. Model vs. Observed Current (2000) Temperatures  Brian, can you add the observed line as an animation? Also, double the thickness of that line Remove shapes on lower right.

13. Projections of Climate Change

14. Annual Climate Changes in 2030: Business as Usual CO 2 Scenario  All GCMs show warming of 3-4°F  Little variability in temperature  Higher variability in precipitation  GCM average precipitation decreases by 7%

15. Summary of Projected Climate Change in 2030  Temperatures are projected to rise  GCMs project a 3° to 4°F rise  Little variability among models  Little variability among CO 2 scenarios  Adds confidence to interpretation  Warming most pronounced during the summer  Precipitation changes are uncertain  there is high variability across the GCMs

16. Potential Climate Changes in 2075: Business as Usual CO 2 Scenario  All GCMs show warming of 8° to 9.4°F  Little variability in temperature  Much higher variability in precipitation

17. Summary of Projected Climate Change in 2075  Temperatures are projected to rise  GCMs project a rise of 7.6° to 11.3°F depending on emission scenario  Warming most pronounced during the summer  Precipitation changes are uncertain  Although most models show a decrease (about 10 to 15% on average), there is high variability across the GCMs  Precipitation patterns show strong seasonality with slightly wetter winters and much drier summers

18. Potential Climate Changes in 2100: Business as Usual CO 2 Scenario  More warming: All GCMs show warming of 9.5° to 11.2°F  Continued variability in precipitation

19. Potential Climate Changes in 2100: Business as Usual, Worst Case and Best Case CO 2 Scenarios Annual averages B1:8.5°F A1B:10.4°F A1FI:15.2°F Warming most pronounced in summer  Bad CO 2 scenario almost twice as “hot” as best case CO 2 scenario

20. Summary of Projected Climate Change in 2100  Same as for 2075, except warmer  Different CO 2 scenarios have a large effect on air temperature by 2100:  These differences in future air temperatures have a large effect on snow at Park City in 2100

21. Climate Change Projections Summary  Today; Now: It’s getting hotter  Night temps 2-3  F warmer than in 1970  2030: warms another 3-4  F  Little difference among CO 2 scenarios  2070: large increases in air temp  CO 2 scenarios make a difference  2100: even larger increases in air temp  CO 2 scenarios make even larger difference  Precip: highly variable, not much confidence

22. Climate Change Bottom Line  It’s not gloom and doom  Continues to get gradually warmer  Really large change is 50 to 70 years in future  CO 2 scenarios have a large effect then  What the world does with CO 2 emissions today matters to your grand-children in 50 years  Caveat: These are deviations from average conditions  Science at this time is unable to deal with changes in the frequency of unusual years: droughts, large snow years, etc