SPECIAL REPORT: Year 2100 – Willamette Climate Change

While there’s a real and frequently-abused risk in attributing causes to effects without valid evidence to support the claim, 2012 presented an abundance of phenomena that, taken as a whole, reeked of the effects of climate change. We don’t even have to look up north, where in 2012 the extent of the Arctic sea ice was the lowest ever recorded; or east, to Mecca, which suffered the hottest rainstorm in the planet’s history in May—a 109° F deluge.  We need only look here, in the Willamette Valley, where the Mary’s River reached record flood height in an abnormally strong deluge in an altogether unusually variable winter; where the normal summer dry-spell throughout July, August, and September shattered records up and down the Valley, a microcosm of an unusually dry summer that featured Oregon’s largest wildfire in more than a century.

Look, we don’t know what will happen with the global climate. Part of our uncertainty lies in the ambiguousness of the actual amount of greenhouse gasses we’ll continue to pump into the atmosphere. But emissions rates largely depend on the greenhouse gas-reducing policies and incentives that world governments craft with one another and their own constituents, and there has been nothing but abject failure after failure in this regard on both international and domestic fronts. It’s a safe if tragic bet that greenhouse gas emissions—and thus by default the earth’s temperature—will continue to rise.

But we also don’t know what will happen with our global climate because we are uncertain as to how sensitive the climate is to those emissions. But we know it’s getting hotter: nine of the 10 warmest years on record have occurred since 2000. And we know that it’s only going to get hotter: global temperatures are projected to continue to rise over this century, anywhere from 2 to 4° F by 2040 to 9.3° F. by 2100. We have made leaps and bounds in our ability to model global climate and to draw convincing projections from these models. But they don’t downscale very accurately, so there is still much insecurity as to what exactly will happen in the 5,200 square mile Willamette Valley by the end of the century. For example, a Japanese climate model projected a 12° F increase in the Pacific Northwest by 2100; an Australian model projected a 6° F rise in the same timeframe.

So we know that the climate may not change exactly as we expect. We know that the effects of a changing climate will be nuanced from region to region, from micro-climate to micro-climate. We know we need more analysis, at finer spatial scales, just as we need less uncertainty. But really, on a certain level, knowing that temperatures will rise, steadily, is knowledge enough. For even the most conservative projections—that global temperatures will rise 2º F by 2040—depict an extraordinarily rapid rate of change compared to changes in the last 10,000 years.

The potential myriad impacts of even this conservative estimate are far-ranging and potentially devastating for the Willamette Valley as we now know it. We’ll take the liberty of examining a few key ecological processes and players below, in hopes they might provide, if not keys to the future, at least signposts by which we can track the Valley’s future.

Photo by Genevieve Weber


There is still uncertainty over what a warmer climate will mean for the Valley’s dry summers—according to a study published by the University of Oregon’s Climate Leadership Initiative, “spring, summer, and fall precipitation varies substantially among the different models, from a spring monsoon to late summer drought.” As for our winters, however, there is common consensus: less snow and more flooding.

Because warmer air holds more moisture than colder air, wet places like the Pacific Northwest are projected to get even wetter. Unfortunately, most of this precipitation will come in the form of winter rain rather than snow.  In fact, according to the United States Global Change Research program, Cascades snowpack is projected to decline as much as 40 percent by the 2040s. This poses a number of significant problems.

More winter storm rain, in addition to a likely increase in rain-on-snow events, could lead to a significant increase in winter flooding in river basins across the Willamette Valley. Another significant problem is that, well, we need that snow. The Valley typically receives only two inches of rain over the summer months, and Valley residents—human and nonhuman alike—rely heavily on snowpack to replenish aquifers and sustain streams and rivers. Indeed, a significant amount—anywhere from 40-80 percent—of the Willamette River’s summer flow comes from the Cascades’ winter snowpack. Finally, not only will high temperatures reduce snowpack and thus reduce peak flow, but they’ll change the timing of runoff: snowpack will melt earlier in the season.

All this is only augmented by the fact that the Willamette Valley’s population—already home to about 70% of Oregon residents—is projected to nearly double by 2050. And whereas current water use patterns vary from place to place, average daily household water use in the U.S. is 350 gallons. If late summer flow is to be severely reduced from its already low and allocated levels, even less water will be available for municipalities and irrigated agriculture, at the exact time it’s needed most.


A changing climate lays bare the fundamental ecological principle of connectedness; as John Muir put it: “When we try to pick out anything by itself, we find it hitched to everything else in the Universe.” So with diminished snowpack and earlier snowmelt comes increased risk of wildfire. A climate study published this summer in Ecosphere suggests that over the next 30 years, 38 percent of the planet will see increases in fire activity. By the end of the century, that number is projected to be 62 percent. But “fire activity” isn’t relegated to frequency; projections call for bigger fires, longer durations of these fires, and longer wildfire seasons. Oregon is no exception—a reduced snowpack, combined with the likelihood of warmer and drier summers, will result in increased wildfire activity in all Oregon forest types. This includes even the wetter forests west of the Cascades—the slopes and foothills of the Willamette Valley, and the Coastal Range. The Tillamook may burn again. Amplified wildfire activity will detrimentally affect the logging industry, increase storm runoff, and affect air quality, especially in the inversion-prone Willamette Valley.

More pests…

Hitched to wildfires are certain species of animals that will flourish in a warming climate. Take bark beetles, largely responsible for the deaths of billions of trees across millions of forest acres from Alaska to Mexico. Warmer winters allow them to survive “low-temperature induced mortality” and even reproduce annually, rather than every two years. According to a 2010 study conducted by the U.S. Forest Service, the potential for infestations of spruce and mountain pine beetles in western North American forests is likely to increase significantly in the coming decades. Beetle-killed or weakened forests, it should be noted, are susceptible to large wildfires. There’s also the fact that beetle-killed forests can no longer remove carbon dioxide from the atmosphere, which only strengthens an already unfortunate feedback loop.

…less fish.

Native salmon will not be so lucky. Water temperature, flow, sedimentation and snowpack melt—all of which will be affected by climate change—impact salmon at each stage of their life cycle.  According to the USFS Aquatic Ecology and Management Team, climate change effects will be “experienced differently by different salmon in different habitats throughout a stream network.” Critical breeding estuaries may be submerged by rising seawater, while salmon higher in the stream system may be affected by changes in precipitation timing that alter flow regimes and make existing spawning and rearing habitats inhospitable. Increased water temperatures also lead to higher rates of disease transmission and development—a number of studies have shown that in water temperatures above a certain threshold (17-18˚C) salmon populations can be decimated by disease and parasites.


As for how the Willamette Valley’s agriculture will be affected, we simply don’t know. As the Oregon Climate Change Research Institute puts it, “Depending on the crop/commodity and its current climatic equilibrium, temperature and/or precipitation changes can either reduce or increase yields and/or quality.” We do know that the Willamette Valley’s rich and diversified agriculture owes much to the Valley’s mild climate—the temperature rarely exceeds 98° F or drops below 16° F.

As that climate shifts, so will the agriculture; and depending on how our local climate adjusts, this could be for the better or worse. Take wheat, for example, of which farmers grew 100,000 to 125,000 acres this summer. Crop ecologists estimate that for each 1° C rise in temperature above the norm during the growing season, grain yields decline by roughly 10 percent. So that’s gloomy. On the other hand, farmers are generally a resilient and adaptable bunch—they’ll plant something other than wheat; with a warmer climate and longer growing season, they’ll be able to plant any number of additional crops that the Valley climate wasn’t previously able to support.

An interesting example of the nuanced future is found in the Valley’s wine industry.  On the whole, a slightly warmer climate will be good for Oregon’s wine country. According to a study by scientists at Stanford University, the Willamette Valley could see a slight increase in the amount of total acreage suitable for wine and a large increase in total acreage suitable for more valuable grape varieties.  The problem is that the study’s findings were based on the conservative assumption that average global temperatures will rise about 2° F by 2040. If temperatures rise beyond that, as they likely will, farmers could employ a number of adaptive techniques—planting heat-tolerant vines, earlier ripening rootstocks, planting on north facing slopes or higher elevations, etc.

But there’s only so much wiggle room: grapes aren’t annuals (a grower doesn’t have the choice to plant something different every fall and spring); grape vines are slow to mature and, once mature, they’re productive for decades, even centuries. Grapes are a significant investment. High-end varieties like pinot noir, which makes up 60 percent of total acreage and wine production in Oregon, favor a fairly small climactic niche—interestingly enough, it was only due to the general warming of the last few decades that the Valley developed an optimal climate to grow pinot noir. Any shift in weather may significantly affect these favorable growing conditions, and thus the quality of the wine.

And the thing about climate change is that it’s not just going to produce wetter winters and drier summers, it’s projected to induce far more fluctuations, far more extremes in temperature. And in the end, if temperatures continue to ascend towards the hellacious levels predicted for the latter half of the century by many climate models, the future of Oregon’s $2.7 billion wine industry is bleak to the point of despair.


Indeed, much of climate change—even just contemplating the potential effects—has the tendency to lead one to the point of despair. But there is still hope: in mitigation, in resilience and adaptation in the face of a fast-changing world. In fact, there are innumerable organizations and institutions studying climate change mitigation and potential human adaptations on numerous scales—they offer hope that we can meet one of the greatest challenges our species has ever faced. Hubris and unintended consequences may have gotten us into this mess, but there’s still the slim chance that human ingenuity and hardiness will see us through. There’s also the long view—yes, climate change effects will likely result in the decline and possible extirpation of Chinook salmon, steelhead, and Oregon chub, but salmon have been around a long, long time. According to Robert Behnke, in Trout and Salmon of North America, fishes “recognizable as salmonids” were present some 100 million years ago—they’ve been through such changes before.  We humans have weathered our own share of changes; we can hope to prove as adaptable as salmonids. The ancient Chinese adage says “may you live in interesting times.” They meant it a curse. We can hope it is a blessing.

By Jared Wallace