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Fifth National Climate Assessment - Read the Report

Modeling future climate, vegetation, and hydrology in the Pacific Northwest

Regional climate projections can provide information on likely future changes in climate, ecosystems, and water resources at useful scales. 

In the Pacific Northwest, average temperatures are projected to increase by at least two and up to 15° F by end of the century, dependent on future greenhouse gas emissions levels. Winters are expected to become wetter and summers drier, snowpack will likely decrease substantially, and snowmelt runoff may occur earlier in the year. Wildfires are projected to become more frequent and more severe, and forest types are expected to change.

Because the impacts of climate change vary from place to place, regionally-specific climate projections are critical to helping farmers, foresters, city planners, public utility providers, and fish and wildlife managers plan for the future. A project jointly funded by the DOI Northwest Climate Science Center and NOAA’s Pacific Northwest Climate Impacts Research Consortium sought to address this need. Researchers first evaluated the ability of the Earth system models to simulate historical climate patterns in the Northwest. The best-performing models were then downscaled—that is, transformed from a global scale to a regional scale. Researchers then used the downscaled models to project likely future changes in climate, vegetation, and hydrology in the region.

The result was a series of publicly-available datasets that can be used to develop strategies for reducing the impacts of climate change specific to the region’s ecosystems, agricultural systems, and built environments. For example, the data can be used to understand how the number of frost-free days and minimum average winter temperatures might change— information that can help forest managers project changes in pest populations such as the mountain pine beetle, which are typically killed by freezing temperatures. The data can also help managers identify forests and grasslands that are most vulnerable to climate change, enabling them to prioritize investments to increase the resilience of these landscapes. This type of information on projected changes in climate, vegetation, and hydrology is vital as resource managers seek to plan for the impacts of climate change and develop effective land management plans in the face of uncertain future conditions.