Many parts of the American West, including Oregon, have entered or will enter if global warming, driven by the burning of fossil fuels, continues unabated.
That鈥檚 according to a new paper published in the Proceedings of the National Academy of Sciences this week.
鈥淲e鈥檙e not coming back to any kind of normal by today鈥檚 standards,鈥� said Samantha Stevenson, the paper鈥檚 lead author and an assistant professor at the University of California, Santa Barbara.
Normal refers to the amount of water expected to be available for people, plants and animals at any given time. When the actual amount of water available falls short of that norm, .
The researchers used climate models to predict future precipitation and soil moisture levels, assuming that greenhouse gas emissions stay high. They found that what鈥檚 now considered a long-lasting and intense drought in parts of the American West is becoming the norm over time.
That鈥檚 the case in Oregon, which is gradually drying out.
More than one-third of Oregon, on average, has been in severe drought or worse from 2000 to 2020, . Three-quarters of the state remained in this week.
鈥淥ur climate is becoming drier,鈥� said Erica Fleishman, director of the Oregon Climate Change Research Institute, which publishes the assessment. 鈥淎nd what we thought of as 鈥榥ormal鈥� water availability 50 years ago is just not something that we can consider normal anymore 鈥� and we鈥檙e seeing that statewide.鈥�
Historically, Oregon had wet seasons and dry seasons. Rain soaked the western portion of the state in the winter while snow blanketed mountain ranges. Central and Eastern Oregon especially relied on a gradual melting of that mountain snowpack to feed rivers and streams throughout the summer.
As the state becomes drier, Fleishman said, Oregon will continue to have wet days, but what Oregonians know as a wet season may become a thing of the past.
鈥淭hat leads to questions about what can be supported across the state,鈥� Fleishman said. 鈥淚t鈥檚 not just the amount of water that we need to be thinking about, it鈥檚 what are some of the secondary effects of having less water.鈥�
The shifting definition of normal presents challenges to humans, whose built environment is constructed around a fixed definition of normal and a range of extremes. Plants and animals too often depend on water .
Adapting to this particular effect of climate change, Stevenson said, requires a shifting baseline or definition of normal and, thus, a more fluid definition of drought.
鈥淚f we are managing [water] with the expectation that any drought that begins will be temporary and we will recover back to where we started, that鈥檚 probably not an accurate assumption,鈥� Stevenson said. 鈥淲e should plan for any recovery to come back to a slightly drier state than where we were when the drought started.鈥�
According to the study, both parched and wet places will still experience wetter-than-average times and drier-than-average times, but there will be new averages and new extremes.
鈥淐limate change is here,鈥� Stevenson said. 鈥淪o we need to be thinking right now about what changes we need to make to our policy systems and our social systems in order to be prepared.鈥�
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