Climate Change in the PNW

Climate Change and The Pacific Northwest

The Pacific Northwest is bordered by the Pacific Ocean to the west and encircled by the Rocky Mountains to the east.

Changes in temperature and precipitation levels are expected to continue into the future and lead to lower winter snow levels, affecting stream flow as well as water quality throughout the region. Increased temperatures result in more winter precipitation instead of snow fall, especially in mid-elevation basins that experience average winter temperatures near freezing leading to:

1. Less winter snow accumulation


2. Higher winter streamflows


3. Earlier spring snowmelt


4. Earlier peak spring streamflow and lower summer streamflows in rivers that depend on snowmelt (most rivers in the Pacific Northwest)

(Pacific Northwest Climate Change and Water)

 

"The decline of the region's snowpack is predicted to be greatest at low and middle elevations due to increases in air temperature and less precipitation falling as snow. The average decline in snowpack in the Cascade Mountains, for example, was about 25% over the last 40 to 70 years, with most of the decline due to the 2.5 degrees F increase in cool season air temperatures over that period. As a result, seasonal stream flow timing will likely shift significantly in sensitive watersheds."
(fws. gov, 2011)


Peak streamflow in the Quinault River is projected to peak earlier in the year. Increased temperatures will likely contribute to earlier snowmelt and major changes in the timing of runoff. As a result, the peak of spring runoff is projected to shift. This shift will impact an keystone species of the PNW as well as it's ecosystem. (water.epa.gov, 2012)