Portland's highest-ever temperature in June was shattered, resulting in 116 degrees. On Monday, the record for for cold weather also fell as the city was blanketed in harsh, wet snow.
Extreme weather events are expected to become more common, according to Erica Fleishman, a professor at Oregon State University and the director of the Oregon Climate Change Research Institute.
As the climate changes, all kinds of weather extremes will be more likely, she said, noting that while the Earth is becoming warmer on average, there is some evidence that winter storms are becoming worse because of climate change. Cold extremes are not becoming more common, but there is also evidence about the incidence of winter storms.
Fleishman explains that, obviously, weather extremes have occurred as long as there has been weather, and that records have been broken as long as they have been maintained.
Despite this, records are being broken in different ways of late. An estimated that between 1999 and 2019, the number of record-low temperatures in the United States was about twice the number of.
In a calm climate, the number of people would be nearing identical.
Events like the event of late June in Oregon are evident, which is likely to have occurred at that depth without the warming effects of climate change, and experts in identifying connections.
While the heat dome, which killed nearly 100 people in Oregon, was a 1-in-1,000 year event, it might be more like a 1-in-10 year event by the end of the century if more isn't done to reduce greenhouse gas emissions, according to Fleishman.
Extreme weather is often caused by the absence of things like rain, as is evident in the ongoing drought that has left many parts of central and southern Oregon covered. According to the US Department of Agriculture, recent winter weather in the northwest corner of the state has helped stabilize the state's snowpack, which acts as a natural reservoir, but much of the rest of the country is quite short of historical snowpack averages.
The Department of Agriculture estimates that many of Oregon's river basins are well below historical averages for snowpack, contributing to the region's ongoing drought.
So far this year, seven Oregon counties have declared drought emergencies, and four additional states have submitted requests for the declarations.
Cold weather events are more difficult to control, but scientists are aware that climate change destabilizes previous forecast weather patterns, causing all kinds of extreme weather to be more likely.
"Even if we are getting snow in April, it may seem antithetical to climate change, but the fact is that unusual extreme weather of any type is compatible with climate change," Fleishman said.
A member of the United Nations Intergovernmental Panel on Climate Change, a group of over 234 experts, warned that as the climate continues to warm, some places will be affected by several extreme weather events at once, like in Oregon, where one side of the state receives late-season snow while the other sees snowpacks less than half of previous levels.
UN Secretary-General Antonio Guterres described the report as "code red for humanity."
Over the long term, Fleishman said, the only way to reduce the probability of extreme weather events is to drastically reduce or eliminate greenhouse gas emissions altogether.
Clarification: A quote in the story was updated to clarify that cold extremes aren't expected to become more common due to climate change, although some evidence suggests winter storms may be intensifying.
Kale Williams; 503-294-4048; @sfkale