As the climate warms, forests across the Northwest will experience increased disturbances from wildfire, drought and disease. Parts of the region that historically were habitat for certain tree species will no longer be suitable for these species as the temperatures warm.
Drier, warmer conditions are likely to increase the annual area burned by forest fires.
Wildfire is a natural component of a forest ecosystem; wildfires clear out dead and dying plants, allowing others to grow better and healthier. Wildland fire in the right place at the right time contribute to an overall healthy ecosystem.
But climate change is increasing the risk of large, uncontrolled wildfires which threaten people and society.
Large wildfires reduce air quality, increase hospitalizations related to respiratory conditions, reduce timber resources and limit opportunities for outdoor summer recreation. Uncontrolled wildfires near communities also put at risk people’s lives and livelihoods; homes and businesses.
The year of 2015 – the warmest year on record for the Northwest – was the second-largest wildfire season in the region’s recorded history (2020 was the largest). Northwest average temperatures were about 4.8°F (2.7ºC) warmer than pre- industrial times.
More than 1.6 million acres burned across Oregon and Washington in 2015, incurring more than $560 million in fire suppression costs. In 2020, nearly 2 million acres burned across Oregon and Washington.
The extreme climates of 2015 and 2020 provided a preview of future wildfires in the Northwest if greenhouse gas emissions are not dramatically reduced.
Insect outbreaks and disease are also projected to increase in the coming decades, with largely negative consequences for forests.
Insect outbreaks and tree diseases, like wildfire, are disturbances that can kill trees. Like wildfires, they are also a critical component of a healthy forest. As the climate changes, however, some insect outbreaks and diseases are projected to become increasingly common.
When diseases and insect outbreaks become more widespread and severe than what is normal for the natural system, the forest may be less able to provide ecosystem functions, such as carbon storage, clean water, and habitat for the wildlife that depend on the forest.
Climate change is expected to reduce the establishment, growth and distribution of some trees and other plants – transforming forests in the Northwest during the next century or more.
Trees with particular ecological and economic importance for the state – Douglas-fir, western redcedar, pine species and subalpine forests – are susceptible to the changing climate.
Areas of the state with moist, temperate climate are projected to shrink. Tree growth may increase in some areas, while declining in others. Tree growth in some areas may “push out” meadow and other non-forested habitats.
Disturbances such as insect outbreaks, disease, drought and fire will lead to the most rapid changes in forests, as opposed to species establishing in more suitable climates.
In addition to being stunning and emblematic landscapes of the Northwest, forests provide clean air and water, critical habitat and ecosystems for wildlife and have deep significance for Indigenous livelihood and culture. Taking action today to prepare our forests for more wildfire and other disturbance – for example, by planting tree species with greater resistance to wildfire and reducing surface fuels to reduce fire severity in fire-prone forests – will help ensure Northwest forests thrive in our future climate.
Credits:
Created with images by Bobby Stevenson - "Pacific Northwest" • Nick Bolton - "Smoke from wildfires sits over the trees at the base of buckhorn pass." • Andy Feliciotti - "PNW Forest Aerial" • Maria Shanina - "Douglas firs" • Dave - "Sometimes I like to think about what trees are thinking about while I’m hiking between them." • Justin Kauffman - "Lost in the woods" • marcinjozwiak - "road drone aerial" • Jordan Steranka - "untitled image"