Southern Oregon is being hit hard by warming temperatures that worsen wildfire risk and reduce snowpack, but local agriculture could benefit from longer growing seasons, according to a new climate change report.
The Oregon Climate Change Research Institute at Oregon State University released its 2019 climate assessment Friday. The Legislature has mandated the periodic reports.
“Southwest Oregon is sort of a ground zero for a lot of this with the many recent years with poor snowpack and fires and smoke,” said Philip Mote, a co-author of the fourth Oregon Climate Assessment Report and former director of the institute.
Southwest Oregon, in addition to other parts of the state, experienced back-to-back summers with wildfires that threatened communities and smothered the area with smoke for months.
“Simply put, the state’s biggest fire years occur when summers are unusually warm and dry,” Mote said. “Since warm and dry summers are occurring more frequently, we can expect fire danger to increase as well.”
The 2019 climate report predicts most areas of the state will experience 30 more days of temperatures above 86 degrees by midcentury.
By 2100, Oregon will be 4 to 9 degrees warmer. April 1 snowpack levels will drop by more than 56 percent, according to climate models.
During the winter of 2013-14, the Mt. Ashland Ski Area was closed for the whole season due to lack of snow. It operated on a limited scheduled the next winter as the low-snow conditions persisted, and has been able to offer a regular schedule this winter.
Mote said global human activity is increasing the amount of heat-trapping gases in the atmosphere, contributing to the long-term climate shift.
“There’s always been weather. There’s always been variability in climate. But we’re seeing this gradual shift over time toward warmer, drier summers, lower snowpack and more wildfires,” he said.
Longer fire seasons
Like many who experience fighting wildfires, Rogue River-Siskiyou National Forest Supervisor Merv George said risky wildfire conditions are no longer confined to summer months.
“I’m not so much convinced that we have a traditional fire season anymore,” he said. “And I’m thinking that it won’t be long and we’re going to be navigating much longer seasons — potentially to the point where it’s going to be a fire season year-round.”
George said crews are seeing drier-than-normal fire fuels this winter as they work on prescribed burning projects to reduce wildfire risk.
Mote said that may be an anomaly this year caused by a dry fall. The climate report doesn’t predict less precipitation in the winter. However, more of that precipitation will fall as rain rather than snow.
The report does show an increase in the number of days per year when fuel moisture will fall below 3 percent. Very low moisture levels lead to extreme fire risk.
The Willamette Valley in northwest Oregon and the eastern third of the state will see the biggest drop in fuel moisture.
Mote said scientists didn’t know what to think when climate models started to predict more wildfires in the Willamette Valley and on the western flanks of the Cascades several years ago.
Then, the destructive Eagle Creek Fire charred 48,861 acres in the Columbia Gorge east of Portland in 2017.
Wind and excessive heat caused the fire to rapidly increase in size, according to firefighters.
“So, given enough time, even these very wet forests do dry out and can burn pretty spectacularly,” Mote said.
For “smoke refugees” fleeing parts of Oregon, worsening fire risk in northern Oregon could mean fewer options for escaping smoke.
Irrigation, farming and growing
Reduced snowpack will cut into summer water supplies for irrigation and drinking water, the report says.
In 2015, much of the Western United States recorded record low snowpack levels, Mote said.
Warmer springs and falls are lengthening the growing season by one to two months, which could benefit agriculture, the report says. For example, more grape varieties will be able to grow in Oregon. California, meanwhile, is likely to suffer as temperatures grow too hot to support some crops, Mote said.
Increased carbon dioxide levels will cause crops to grow better, but weeds will thrive — causing problems for farmers and ranchers, he said.
The authors of the climate report said the various changes in Oregon represent a new norm.
“The disruptions to local economic activity from fires have become almost routine and regional air quality has suffered, leading to respiratory ailments,” said Kathie Dello, co-author of the report and associate director of the Oregon Climate Change Research Institute.