Recent Climate Change Modeling Results Eric Salathé Climate Impacts Group University of Washington.
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Transcript of Recent Climate Change Modeling Results Eric Salathé Climate Impacts Group University of Washington.
Recent Climate Change Modeling Results
Eric SalathéClimate Impacts Group
University of Washington
Global Climate Models20th Century Validation
IPCC Scenarios for Pacific Northwest Climate Change
2-10 ºF1.6-4.3 ºF
0.7-1.8 ºF
Range of Projected Climate Change for the Pacific Northwest from Latest IPCC Climate Simulations
21st Century Change
Shift in Pacific Storm Track
Salathé, Geophys Res Lett, 2006
Observed
20th Century Model Composite
21st Century Model Composite
Downscaling
Empirical Downscaling• Assumes climate model captures temperature and precipitation trends• Quick: Can do many scenarios• Shares uncertainties with global models
Regional Climate Model• Based on MM5 regional weather model • Represents regional weather processes• May produce local trends not depicted by global models• Additional modeling layer adds bias and uncertainty
Downscaling Methods Used in CIG Impacts studies
Mesoscale Climate Model
Based on MM5 Weather Model
Nested grids 135-45-15 km
Nudging on outermost grid by forcing global model
Advanced land-surface model (NOAH) with interactive deep soil
temperature
Potential Surprises
• How does loss of snowpack feed back on the climate?
• How do changes in the winds affect the local climate?
• Are their changes in cloudiness that can affect the local rate of warming?
MM5 Simulations
• ECHAM5 global model to force the
mesoscale system
• 1990-2000
to see how well the system is working
• 2020-2030, 2045-2055, 2090-2100
Climate Change
1990s Validation
Obs Record Max
Obs Record Min
Obs Mean Max
Obs Mean Min
MM5 Min
Day of Year
Tem
pera
ture
(°F
)1995 Daily Max and Min Temperature at SeaTac
MM5 Max
1990s Validation
Gridded Observations MM5 - NCEP Reanalysis MM5 - ECHAM5
January
July
1990-2000 Mean Surface temperature
Evaluation of Future Runs
Because there are some biases in the GCM runs, results for future decades (2020s, 2040s, and 2090s) will be evaluated against the ECHAM5-MM5 1990-2000 baseline
Winter Warming
1990s to 2050sTemperature Change
Difference betweenMM5 and ECHAM5
Loss of Snow cover and Warming
Snow Cover Change Temperature Change
Consistent trend over 21st Century
2020s 2050s 2090s
MM5 Compared to raw Climate model
2020s 2050s 2090s
Spring
1990s to 2050sTemperature Change
Difference betweenMM5 and ECHAM5
Pressure gradient and Cloud
Pressure Change Cloud Change
Trend over 21st Century
2020s 2050s 2090s
2020s 2050s 2090s
MM5 Compared to Raw Climate Model
Winter Trends at Various Stations
MM5 - ECHAM5 10 IPCC Models
Applications: Air Quality
Applications: Hydrology
Summary
Projected Pacific Northwest Climate Change
warming: 1/4 to 1 ºF/decade
Probably more warming in Summer than Winter
Precipitation changes uncertain – Possibly wetter winters and drier summers
Challenges
Deficiencies in Global model propagate to regional model
Biases from regional model
Mesoscale model simulates different climate signal from global model
Loss of snow amplifies warming in Winter and Spring
Increased cloud cover in Spring -- reduces effect of snow loss