Statistically Downscaled Climate Projections of Temperature, Precipitation, and Snow for Wisconsin. Michael Notaro

Transcription

1 Statistically Downscaled Climate Projections of Temperature, Precipitation, and Snow for Wisconsin Michael Notaro Associate Scientist Center for Climatic Research University of Wisconsin-Madison Collaborators: Dan Vimont, Dave Lorenz, Steve Vavrus, Chris Kucharik, Katie Holman, Kristie Franz

2 IPCC: Intergovernmental Panel on Climate Change Established by World Meteorological Organization and United Nations in Assess risk of human-induced climate change, potential impacts, and options for adaption or mitigation. Latest: 4th Assessment Report (AR4) Warming of the climate system is unequivocal and very likely due to human activities Nobel Peace Prize Dozens of climate models have been run to assess the climatic response to a continual rise in CO 2 and potential impacts

3 IPCC Emission Scenarios 820 (*2.9) 550 (*1.9) 375 Uncertainty due to Varying Emission Scenarios

4 IPCC AR4 WG1 Mitigation vs. Adaptation Scenario doesn t matter 2025: +1 C Scenario does matter 2100: +2-4 C Mitigate (Governor s Task Force) Adapt (WICCI) A2: +3.6 C B1: +1.8 C Constant: +0.6 C

5 150-km Typical GCM Grid Spacing D. Lorenz Mean Wisconsin temperature and precipitation for 15 IPCC climate models for Black line: Observed 150-km Average WI County GCMs are coarse GCMs have climate biases

6 Statistical Downscaling & Debiasing We want to remove climate biases from the IPCC models and use statistics to translate the data to a higher resolution. Dan Vimont

7 ccr.aos.wisc.edu/cwg

8 Annual Daily High Temperature Trends ( F) Observed A1B 1980 to F +6.1 F

9 Annual Daily Low Temperature Trends ( F) Observed A1B 1980 to F +6.8 F More warming at night and more warming up north and away from Lake Michigan

10 Annual Precipitation Trends (inches) Observed A1B 1980 to Wetter

11 Projections for Late 21st-Century for Wisconsin More warming in cool season Wetter in cool season, drier in summer

12 More certain Projected Change in WI Precipitation by the Mid-21st Century, A1B Scenario N = 14 models Less certain A wetter winter-spring is more certain than a drier summer. Mean Median J F M A M J J A S O N D

13 Projected Changes in Wisconsin Precipitation A2 By the Mid-21st Century J F M A M J J A S O N D A1B B1 By the Late-21st Century A2 J F M A M J J A S O N D A1B B1 = 75%+ of models project a wetter WI = 75%+ of models project a drier WI = All but 1 model (or 0) project a wetter WI

14 Range of Projected Changes for Chequamegon-Nicolet National Forest (A1B Scenario for Mid-21st Century) Not one single answer, but a range of projections!

15 Projected Change in the Frequency of Cold Nights <0 F Days Per Year (A1B Scenario) Modern: 18 times/year in S, 40 times/year in N Mid-21st Century Late-21st Century (1 to 3 weeks less) (1.5 to 4 weeks less) Less very cold nights

16 Projected Change in the Frequency of Hot Days >90 F Per Year (A1B Scenario) Modern: 12 times/year in S, 5 times/year in N Mid-21st Century Late-21st Century (1.5 to 3 weeks more) (3 to 6 weeks more) More very hot days

17 Average Growing Season Length (5 C = 41 F) (A2) Longer growing season Difference (23 days longer)

18 1990 USDA Map 2006 USDA Map PLANT HARDINESS ZONES National Arbor Day Foundation

19 Northward Shift in Plant Hardiness Zones Dane County 5a -> 6b Washburn 3b -> 5b

20 Wisconsin Tension Zone Will it shift northward? Curtis; Lorenz Present Day Mid-21st Century (A1B) Late-21st Century

21 Projected Change in the Frequency of One Inch Precipitation Events (days/decade) (A1B Scenario) Mid-21st Century Late-21st Century (5 to 10 more days) (9 to 14 more days)

22 Projected Changes in Annual Snowfall (cm) Projected % Changes in Annual Snowfall Projected Changes in Mid-March Snow Depth (cm) Projected % Changes in Mid-March Snow Depth

23 Projected Change in the Probability that Falling Precipitation in Rhinelander will be Frozen (A1B Scenario) Mid-21st Century Late-21st Century Shorter snow season in Wisconsin

24 Projected Snow Change in Chequamegon-Nicolet National Forest: Late 21st Century A1B versus Modern Projected Change in Averaged Snowfall (inches/day) Projected Change in Averaged Snow Depth (inches) Modern Future Snow Season Duration Based on 1 + depth Modern: Nov 15 - Apr 15 (152 days) Future: Nov 29 - Mar 26 (118 days) Snow season reduced by 5 weeks, most notable in spring.

25 Projected Change in Chequamegon-Nicolet National Forest: Late 21st Century A2 versus Modern Nov-Apr T vs Snowfall Nov-Apr P vs Snowfall r=-0.86, N=33 r=+0.70, N=33 Typical range for projections among 3 realizations: 0.07C for T, 1.70 cm for P, 8.06 cm for Snow

26 Summary of Wisconsin Projections - Warming, especially across northern Wisconsin, greatest at night and during winter - Increased precipitation, especially during winter-spring - Fewer cold surges and more heat waves - Longer growing season - Northward shift in plant hardiness zones - Northward shift in tension zone - More frequent heavy precipitation events - Shorter snow season, with less snowfall and snow depth

27 DATA SUMMARY Tier-1 Variables: Daily Maximum Temperature Daily Minimum Temperature Daily Precipitation Tier-2 Variables: Daily Snowfall Daily Snow Depth Daily Snow Cover Daily Potential Evapotranspiration Emission Scenarios: Modern: 20C3M Future: A2, A1B, B1 GCMs: CMIP3 GCMs per scenario PDF of daily projections, including 3 realizations for each GCM/scenario Resolution: Spatial = 0.1 degree Temporal = Daily Region: N, W The data can be used to compute many other variables, including growing degree days, winter severity index, spring onset date, cooling and heating degree days, etc