One thing I love about the West is that so many people know their elevations. I doubt that many citizens of Atlanta take pride in their thousand-foot-high city. But everyone knows that Denver is a mile high, and most of us are well aware of the elevation of whatever high pass we have to cross in the wintertime. This knowledge of our place in the topography ties us to the land in a profound way, and soon, it will open our eyes to the progress of climate change.
My house sits at about 2,300 feet in the foothills of Oregon's Siskiyou Mountains. Over the 15 years I've lived here, I've learned that this is an elevation where things change. Most winters, there are days when the snow piles up on our street, though just 100 feet down slope, the roads are clear. Below us, the natural vegetation is oak woodland; above us, the conifers begin to close ranks into a proper forest. Every spring, the acorn-loving Scrub Jays and the conifer-dwelling Steller's Jays do battle over our yard.
This invisible ecological boundary has probably been fairly stable for centuries, wavering a few hundred feet up and down the hillsides with short-term climate fluctuations. It has remained even as the Oregon landscape has been completely transformed over the past 160 years of European settlement. It has remained because it is based not on biology, but on physics. The average temperature decreases by 3.5° Fahrenheit for every 1,000 feet of elevation gain, because the thinner air at higher altitudes can hold less heat. Cooler temperatures change both the water regime -- especially the snow level -- and the fire danger, which together do much to determine vegetation in the West. And so, physics and biology have collaborated to create a noticeable environmental transition right about where I live.
Today, that transition is in transition. The physics that relates temperature to elevation isn't changing, but the baseline temperature is. If global warming produces a 3-4 degree increase in annual average temperature by 2100, as most models suggest, my house will find itself in the climate and vegetation now found 1,000 feet lower. No more snow to deal with, but my Douglas firs probably won't make it, and good-bye, Steller's Jays. Hello, clammy winter fog and a lot more summer days over 100 degrees. It's not a happy picture.
But the truly significant changes will be happening higher, on the 4,000-6,000 foot-high ridges that ring our valley and hold the snow that melts in the spring to feed our creeks and rivers. More than by any other change, global warming threatens the West with a seemingly simple trick: changing snow into rain. Without snowmelt, even if total precipitation remains exactly the same, we are in for a lot of trouble. The timed release of water from snow keeps forest soils moist well into the summer, buffers streams from floods, and allows irrigation districts to manage water distribution throughout the year. This January, I gaze across the valley toward the peaks, and I see no snow. I realize that this is likely a yearly anomaly, but such sights will become the norm soon enough. When that happens, will the West be able to sustain the population we have now, much less the population growth that so many boosters still promote?
This vision of the future has me looking at the topography in a new way. I spent much of the past summer climbing up and down the walls of my valley, ever mindful of the elevation. My friend Jim Chamberlain and I documented these familiar landscapes as if for the first time, collecting natural history information, making notes and taking photographs. Together, we produced a profile of our environment as it is, and a series of meditations on what is to come. This work (available at www.shiftingpatterns.org) has become a focus for community education and discussion about climate change.
Here is what I urge you to do: Look at your home topography. What is your elevation? When the talk of climate change blurs into a fog of generalizations, explore the elevations of places you know and love (Google Earth is a great tool for this). Then imagine them a few degrees hotter, with the climate now found hundreds or a thousand feet lower down the mountain.
That is our future, unless we can convince ourselves to get serious about climate change.
Pepper Trail is a contributor to Writers on the Range, a service of High Country News (hcn.org). He is a biologist and writer who lives in Ashland, Oregon.
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