FINAL DRAFT (2.10.09) – Page 1 Future climate in the Pacific Northwest

• Main Authors: Philip W. Mote, Eric P. Salathé
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: FINAL DRAFT (2.10.09) – Page 3 1. Global climate models; Greenland; Pacific; Antarc*; Antarctica; Ice Sheet
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.544.8633; http://cses.washington.edu/cig/files/waccia/Ch1_Mote_Salathe_final.pdf

Climate models used in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) on the whole reproduce the observed seasonal cycle and 20 th century warming trend of 0.8°C (1.5°F) in the Pacific Northwest, and point to much greater warming for the next century. These models project increases in annual temperature of, on average, 1.2°C (2.2°F) by the 2020s, 2.0°C (3.5°F) by the 2040s, and 3.3°C (5.9°F) by the 2080s, compared to 1970 to1999, averaged across all climate models. Rates of warming range from 0.1 to 0.6°C (0.2 ° to 1.0°F) per decade. Projected changes in annual precipitation, averaged over all models, are small (+1 to +2%), but some models project an enhanced seasonal cycle with changes toward wetter autumns and winters and drier summers. Changes in nearshore sea surface temperatures, though smaller than on land, are likely to substantially exceed interannual variability, but coastal upwelling changes little. Rates of 21 st century sea level rise will depend on poorly known factors like ice sheet instability in Greenland and Antarctica, and could be as low as 20 th century values (20cm, 8”) or as large as 1.3m (50”).