The Washington state legislature tasked the Washington state Department of Ecology, with support from the Climate Impacts Group, to analyze recent national and international climate reports and provide recommendations to Washington lawmakers on whether to amend Washington state’s statutory limits on greenhouse gas emissions (RCW 70A.45.040).

National and international reports on climate change, like the fifth National Climate Assessment (NCA5) and Intergovernmental Panel on Climate Change’s sixth assessment report (IPCC AR6) provide broad information on climate change impacts for the nation and globe. Though useful, this information is often too broad to inform local-scale climate resilience efforts in Washington state.

Previous reports on climate impacts for Washington state have focused on assessing changes at future time periods (e.g., 2050s) and under specific future climate scenarios. In contrast, the recent IPCC AR6 and NCA5 reports included an assessment of climate impacts for specific global warming levels (GWLs). This perspective directly connects climate impacts with global warming targets, making it easier to assess climate risks associated with specific greenhouse gas emissions limits.

From the report: 

“We find that more warming will lead to more frequent and more severe climate change impacts in Washington state. This includes more hot days above 100°F, higher late summer maximum temperatures, more precipitation with individual storms, higher magnitude flood events, lower snowpack, and lower flows in late summer. Increasing greenhouse gas concentrations are also projected to decrease the pH of the global oceans. Sea level is projected to rise globally, with increasing probabilities of greater than 0.3 m, 0.5 m, and 1.0 m of sea level rise with each successive global warming level that is reached in the 2081-2100 period.”

2025 Summary Report on the Science of Human Caused Climate Change and Recommendations for Washington State’s Greenhouse Gas Emission Reduction Limits

Read the Report

Fact Sheet: Global Warming Impacts in Washington State

Washington state faces dramatically different futures depending on choices we make about greenhouse gas emissions, now and in the future. We analyzed some of the changes Washington could experience if global warming reaches 1.5°C, 2°C, 3°C, and 4°C (or 2.7°F, 3.6°F, 5.4°F, and 7.2°F, respectively). This fact sheet shows what Washington looks like under each warming scenario, giving you the local context needed to understand what global climate targets mean for our state.

View and Download a PDF of the Fact Sheet

For questions, contact Anthony Abbott, Washington Department of Ecology, at anthony.abbott@ecy.wa.gov or Matt Rogers, University of Washington Climate Impacts Group, at rawgers@uw.edu