Oregon Climate Assessment Identifies Advances in Climate Science and Opportunities for Resilience

Oregon Climate Change Research Institute Director and CIRC Co-LEad Erica Fleishman shares highlights from the recently released Fifth Oregon Climate Assessment

Erica Fleishman

Every two years, the Oregon Climate Change Research Institute (OCCRI) assesses the state of climate change science and the likely effects of climate change on Oregon. On January 5, 2021, OCCRI released the Fifth Oregon Climate Assessment. This assessment reflects the expertise of more than 30 authors and 20 peer reviewers affiliated with universities, federal and state agencies, Tribes, and non-profit organizations. It was produced in association with the 2021 Oregon Climate Change Adaptation Framework, which calls for a coordinated, multi-agency response to climate change. The Adaptation Framework was produced by the Oregon Department of Land Conservation and Development in collaboration with numerous other state agencies.

An executive summary of the Fifth Oregon Climate Assessment, and the full document, are available at blogs.oregonstate.edu/occri/oregon-climate-assessments. Below are some highlights from the Assessment.

Aligning the Climate Assessment and the Adaptation Framework

The Climate Assessment and the state’s Adaptation Framework recognize that climate change exacerbates existing social, economic, and environmental inequities. The Framework is accompanied by a Climate Equity Blueprint, which provides tools to assist state agencies in equitably delivering climate-change adaptation programs to underserved and overburdened urban and rural communities. The Adaptation Framework will become part of the Oregon Natural Hazard Mitigation Plan, which qualifies the state to receive federal funds for disaster assistance and mitigation. These funds leverage state investments to strengthen infrastructure and increase the resilience of natural systems to hazards that are amplified by climate change. 

Consistent with the organization of the Adaptation Framework, the Climate Assessment addressed not only the state of climate science, but six sectors within which vulnerabilities and strategic responses can be clustered—economy, natural world, built environment and infrastructure, public health, cultural heritage, and social systems.

Advances in Climate Change Science

The Climate Assessment detailed two areas of climate science that are developing rapidly and are highly relevant to CIRC’s work: prediction of weather conditions from about one to four weeks into the future (subseasonal-to-seasonal forecasting), and attribution of extreme weather events. Skillful or accurate weather forecasts require compilation of as many climate observations as possible. But as the number of observations and the duration of a forecast increases, small errors in the observations become compounded. At about 10 days, weather forecasts generally are no better than random chance. However, advances in research, observations, and modeling are improving the duration over which weather forecasts are reliable.

Seasonal-to-subseasonal forecasting has the potential to improve climate adaptation. Increasing the advance warning of weather hazards, such as rapidly developing droughts, heat waves, or floods, increases available preparation time and may improve outcomes. As an example, federal management of reservoirs throughout the year reflects the target amount of water in each reservoir, which usually is quite low during flood season. These target levels were developed decades ago, when weather forecasts were accurate only a few days in advance. If forecasts were accurate two weeks in advance, then higher water levels could be maintained with low risk of flooding. Such adjustments also may would help to mitigate the effects of droughts, which are likely to become more common throughout the Northwest.

During the past decade, the focus of climate change attribution research has shifted from human influences on mean annual and seasonal climate over large areas to those on the magnitude or likelihood of a given extreme event or classes of extreme events. Asking whether climate change caused a certain event, such as a particular hurricane, is less useful than asking whether the likelihood of such events (say, hurricanes in the Atlantic Ocean) has changed. Attribution of an event to human-caused climate change is most feasible for cold events, which are becoming less common as concentrations of greenhouse gases increase, followed by heat events, which are becoming more common. Attribution of droughts and extreme rainfall is moderately feasible. For example, a study published in 2020 discovered that throughout the southwestern United States and most of Oregon, the period 2000–2018 was the second-driest 19 years since the year 800. The study suggested that 47% of the observed soil-moisture deficit during that period reflected the effect of human-caused climate change on temperature, humidity, and precipitation. Attribution is somewhat less feasible for extreme snow and ice storms, and can be quite difficult for fires and severe thunderstorms. 

The Effects of Climate Change on Oregon’s Electricity Supply

Following recent power interruptions in Texas, and the 2020 wildfire season in the western United States, questions about the reliability of the electricity supply and fire-resistant building designs are on the minds of many Northwest residents. The Fifth Oregon Climate Assessment noted that dependencies among the physical and social components of the built environment mean that direct climate-related risks to any one component can become indirect risks to the others. For example, wildfires directly threaten electricity transmission systems and water treatment infrastructure, and pose indirect or secondary threats to communication systems that rely on electricity and water distribution systems that rely on water treatment. 

Oregon’s electrical distribution system is part of the Western Interconnection, a major grid that extends from the Rocky Mountain states to California and includes the Canadian provinces of British Columbia and Alberta. Electricity production by the Western Interconnection is highly sensitive to drought, the percentage of precipitation that falls as rain and as snow, more frequent extreme-precipitation events, and changing air and water temperatures. Despite these challenges, the Western Interconnection has considerable resilience to projected climate-related stresses given the large size of the generation system, its transmission capabilities, and recent improvements in water use and thermal efficiencies. 

As explained in the Assessment, the Northwest has distinct potential for renewable electricity generation via wave energy. Research on transmission of energy produced by ocean waves to the local electrical grid is advancing rapidly. PacWave at Oregon State University recently received a license from the Federal Energy Regulatory Commission to build and operate the nation’s first pre-permitted wave energy testing facility. The facility will become available for commercial testing in 2022. The market for wave energy is projected to reach $700 billion by 2050, and waves ultimately could supply 10% of the global electricity demand. In Oregon, wave energy will complement production of solar and wind energy on the east side of the Cascade Range. Furthermore, due to the relative consistency of the northeast Pacific wave climate, forecasting the potential energy from this source will be more straightforward than forecasting potential energy from other renewable resources. 

Oregon seeks to increase the pace of adoption of zero-emission vehicles. The Climate Assessment highlighted that in the near term, increasing numbers of electric vehicles are likely to raise peak loads and electricity costs in the Northwest regional grid if charging remains unmanaged. For example, after-work plug-ins could increase early evening peak loads substantially. However, these effects are avoidable with effective charging management. Additionally, as the number of electric vehicles grows, smart grid technology has excellent potential to decrease or eliminate electricity price increases and the need for new peak-demand electricity purchases, and to ease the integration of intermittent wind and solar power, and eventually wave power, into the grid supply.

Wildfire. Photograph by U.S. Fish and Wildlife Service, under a Creative Commons license.

Mitigation of Wildfire Risk

During the 2020 wildfires, dense smoke spread through the Northwest, making air quality hazardous for ten days in many areas of Oregon. The Climate Assessment underscored that although the short- and long-term health effects of smoke exposure in the Northwest have not been quantified, evidence from recent fires in Australia and California suggests that health effects will add substantially to wildfire costs.

In 2019, in response to population growth in areas of high wildfire risk, Oregon Governor Kate Brown convened the Council on Wildfire Response. The council recommended the establishment of consistent policies requiring defensible space, or areas cleared of trees and other combustible elements, around buildings. Until recently, the presence of defensible space was viewed as the dominant contributor to structure survival during wildfires, but the Assessment noted that this assumption may be incorrect. For example, an investigation of 40,000 homes throughout California that were exposed to wildfires from 2013 through 2018 indicated that buildings generally were not ignited by the fire itself, but by wind-driven embers traveling up to a mile ahead of the fire front that landed on combustible materials on or inside the building. Strategies for increasing building resilience to fire include enclosing eaves; screening roof vents; replacement of single-pane windows with double-pane windows, which improves their resistance to radiation and cracking; replacement of asphalt roofs with metal, tile, or other materials; and replacement of wood decks and porches with composite materials. Removal of trees and woody plants that touch buildings and overhang roofs also increases resilience, whereas other clearing generally can be moderate.

The process by which OCCRI tracks developments in climate-change science and climate change impacts on Oregon’s natural and human systems is continuous. OCCRI, with which several CIRC researchers are affiliated, provides technical assistance to governments as they develop climate change policies, practices, and programs; and provides climate change information to the public in integrated and accessible formats. OCCRI is a network of dozens of researchers at Oregon State University, its institutional host; Portland State University; and the University of Oregon. We look forward to welcoming several new student members of the team in the coming months to contribute to our sustained assessment efforts.


Erica Fleishman, a professor at Oregon State University, is director of the Oregon Climate Change Research Institute (OCCRI) and co-principal investigator of CIRC.


Featured Image: Photograph by Pat Knight, courtesy of Oregon Sea Grant, under a Creative Commons license.


Acknowledgements: Publication of the fifth Oregon Climate Assessment is consistent with the charge of the Oregon Climate Change Research Institute under Enrolled House Bill 3543 of the 74th Oregon Legislative Assembly.

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