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