Because heat that would otherwise be lost to space is being held in, Earth is getting warmer. Sea level is rising, too. In part this is due to the melting of alpine glaciers, the Greenland ice sheet, and polar ice. But most sea-level rise is actually caused by what oceanographers call thermal expansion: when you heat water, the individual molecules move faster and the water’s volume increases.
Fourth, I looked at the projections for the future made by the Intergovernmental Panel on Climate Change, or ipcc—a Nobel Prize–winning group made up of the world’s most experienced and respected climatologists. The latest (2013) ipcc report is based on computer models of how average annual temperature and precipitation, along with average sea level, will change around the world relative to the average values from 1986 to 2005. The panel did these projections based on four different scenarios about how much co2we will put into the air during the upcoming decades—what they call representative concentration pathways, or rcps. The lowest concentration pathway assumes two things: that future greenhouse gas emissions are as low as any value that’s been used in the literature on climate change, and that they peak in the twenty-first century and are declining by the year 2100. This scenario is possible if stringent controls on emissions are implemented worldwide. In addition, there will have to be a dramatic slowdown in human population growth, a large-scale conversion from fossil fuels to renewable energy, and widespread implementation of carbon capture and storage technologies that don’t yet exist. This Very Low scenario depends on achieving a 50-percent reduction in emissions from 2010 levels by 2050 and no net release of co2by 2100. The highest rcp, in contrast, assumes that annual carbon emissions continue on their current upward trajectory, that human population approaches 12 billion by the year 2100, and that intensive use of fossil fuels—especially coal—continues. In effect, the High scenario is a present-trends-continue or business-as-usual projection. The other two pathways are intermediate between the Very Low and the High. Publishing four schemes, by the way, carries a message in itself: the climate that your grandchildren and great-grandchildren experience depends on what we do over the next few decades.
The ipcc represents the best expertise available, and to date their predictions have been correct. Their first reports with global predictions were published in 1990; a series of analyses published between 2007 and 2015 indicate that those initial projections, along with subsequent updates about changes in temperature and sea level rise, have been accurate. Thanks to the ipcc, we have a sound scientific understanding of how climate is likely to change in the future.
Finally, I asked: What does this mean for Tarboo Creek? In terms of changes in precipitation, the ipcc’s models using middle-pathway greenhouse gas concentrations indicate that in 2100, winters in the Pacific Northwest will be about 8 percent wetter and summers about 8 percent drier, on average. This outcome would increase fire danger substantially, but otherwise most of the trees and shrubs on our planting list could probably cope. Temperature is a different story, though. Under the Very Low pathway, requiring extremely aggressive action on climate change, our average annual temperature in 2100 will be like the Oregon-Washington border today. Under the middle-road pathways, our corner of the world will feel like northern California; if the Very High, business-as-usual emissions pathway is the one we follow, average annual temperatures at our place will be what they are today in Silicon Valley. Our grandson, born in 2015, may live long enough to see that.
This is why things get difficult when it comes to ordering trees. The vegetation in the Bay Area is nothing like what we have near Tarboo Creek today. There is some overlap in northern California and extensive overlap in northern Oregon.
Recent research has already documented that the frequency and/or intensity of wildfires, droughts, hurricanes, and floods is increasing worldwide. In both the United States and on a global scale, the amount of money being spent on natural disaster relief and wildfire fighting, or lost in homes and commercial structures damaged in storms or fires, is rising dramatically—mimicking the increase in co2and average global temperature. The data are like the sounds you’d hear if an elephant were moving around the room. Even if your eyes are closed, you know that something is going on.
If all this noise eventually wakes us up and inspires effective action, carbon dioxide emissions will slow, and we should plant the types of trees already found in western Washington—even though temperatures will probably continue to increase at least until 2050. But if we keep our hands clamped over our ears and sing loudly enough to ourselves, climate change will be severe enough that we would need to plant a forest like that of today’s northern California or even Bay Area. The problem is that this isn’t an option. The climate hasn’t changed enough yet to let many of those species thrive on the Olympic Peninsula—even though it is projected to in fifty to a hundred years.
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A recent study of British Columbia’s forest types, which overlap extensively with the plant communities found in Washington, suggests that climate change will have two major impacts: today’s high-elevation forest types and alpine meadows will shrink or disappear, and tree species that have a northern range limit in the province may find suitable climates advancing northward at up to 60 miles (100 km) per decade. The trees will have to hustle to keep up; it’s not clear that all of them will make it.
For us, this research boils down to a series of do-we or don’t-we questions. For example, do we plant incense cedar? This beautiful timber tree grows from the west coast of central Oregon down to northern Baja; the pencils you use are probably made from it. Local nurseries grow incense cedar in western Washington and distribute it with a bright yellow non-native species tag. But as climate change continues, the range of incense cedar will head this way. It may be native to the area by the time our grandson is walking the banks of Tarboo Creek with his children. We could ask the same about Port Orford cedar—a tree that yields splendid wood for making arrows and currently grows in southern Oregon.
Another quandary: historically, restoration ecologists have been careful to replant with seeds or seedlings from nearby populations of native species to ensure that the individuals on the new site are similar, in terms of genetic makeup, to what grew there in the past. The idea was that local individuals are adapted to local environments, their genetics having been honed by centuries of evolution at that site. But with climate change, sourcing from local populations is less of a consideration; in some cases it may even be wise to get seeds and seedlings from sites farther south or at lower elevation.
What to do? We are optimists. In the 1950s, Seattle’s Lake Washington was so polluted by a daily dose of 20 million gallons of poorly treated sewage that children weren’t allowed to swim there. There was a general outcry—an expression of what Bill Gates Sr. likes to call the public will. In response, a countywide agency was formed to build and operate a comprehensive municipal sewer system. Water quality in the lake improved quickly, and our boys swam in it as kids. One even did a New Year’s Day polar-bear plunge: he came out cold but clean. Similar scenes occurred throughout North America in the 1950s and ’60s, and the widespread eutrophication of lakes slowed or stopped. In freshwater systems, death through overfertilization is largely a thing of the past.
In the 1970s and ’80s, extensive coal burning to generate electricity in North America and Europe, along with increasing gasoline consumption by cars and trucks, was introducing enormous quantities of sulfur oxides and nitrogen oxides into the air. When these compounds react with water in the atmosphere, the products are sulfuric acid, nitric acid, and nitrous acid—the active ingredients in acid rain. In northern Europe and the northeastern United States, statues were disintegrating and forests were dying. In response, there was another expression of the public will. The U.S. Clean Air Act Amendments of 1990, and similar legislation in other industrialized countries, started a slow but steady decline in the amount of sulfur oxides and nitrogen oxides released into the atmosphere. Forests and lakes began re
covering. The decline in acid rain is still continuing, even though electricity generation and economic output have grown dramatically.
In the 1980s through the early ’90s, the percentage of ozone in the upper atmosphere began decreasing; an ozone hole opened over Antarctica each Southern Hemisphere summer. Ozone absorbs the ultraviolet wavelengths in sunlight and thus protects Earth’s surface from the highest-energy, most dangerous components of sunshine. It’s a sunscreen. The ozone layer was thinning largely because chlorine atoms, off-gassed from refrigerators and air conditioners, were triggering chemical reactions that break ozone molecules apart. Less ozone means more skin cancer and photoaging of skin. In response to the data, there was a third expression of the public will: the international community signed the Montreal Protocol in 1987, phasing out the production of ozone-depleting substances. Limitations on these substances have started to produce significant results. There is still much to be done, but the percentage of ozone in the atmosphere is rebounding. The Southern Hemisphere’s ozone hole has stabilized and may even be starting to shrink.
Similarly, partnerships between government agencies, businesses, and nonprofit organizations in the past fifty years have led to dramatic reductions in littering and smoking. The public will is powerful.
We are optimistic that another expression of the public will—one that starts a slow but steady decline in carbon dioxide emissions—is beginning. Like the response to acid rain and ozone depletion, the response to climate change will have to be international and long term. The Kyoto Protocol, negotiated in 1997, set targets for decreases in greenhouse gas emissions and was signed by virtually every country in the world except the United States. Changes in behavior may be particularly wrenching for Americans because the country developed in an era of cheap gasoline and subsidized highways. The result is land-use patterns that make energy-efficient transportation difficult—I know someone who drives 130 miles round-trip to work each day. So resistance to change is high. But change is also opportunity: people who can adapt and innovate will thrive, while people who look backward and maintain a lifestyle dependent on fossil fuels will see a larger and larger percentage of their income disappear in exhaust. And one of the great messages of my adult life is this: never underestimate the energy, resolve, and creativity of the American people. Indeed, an impressive array of states and municipalities have set ambitious targets for reducing greenhouse gas emissions and limiting future temperature increases—targets that move beyond the terms of the Kyoto Protocol.
So at Tarboo Creek, we plant trees that will grow well now, and we work toward a future that doesn’t depend on fossil fuels. If that future doesn’t arrive, our great-grandchildren will have to replant.
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So back to the question: What to order?
We get most of our plants from state or county agencies that maintain nurseries and sell to private individuals or organizations, but on occasion we grow some of our own. Madrone trees, for example, are difficult to get from the nurseries, so our older son started a little bank of seedlings from fruit that fell on sidewalks near our home in Seattle. Madrones are a broad-leaved evergreen tree, an anomaly in northern latitudes. They have shaggy orange and brown bark and dominate bluffs and other gravelly sites—especially near the coast—where other trees struggle. We found a few in our woods when we first bought the place so wanted to increase their numbers. We’ve also worked on growing Sitka mountain ash, beaked hazelnut, and evergreen huckleberry.
Almost everything else we need, though, is available from suppliers. So in fall we sit down, look over the websites published by the nurseries, and figure out how many individuals we want of each species on their lists. We do this figuring based on the old gardener’s dictum: put the right plant in the right place. To grow a forest well, you have to know your site and your trees.
As we walk over an area we’re going to plant, we try to notice the exposure and the slope. How much sun will the trees get here, and how quickly will water move downslope? Sitka spruce love to have their feet wet, and western redcedar can form lush, single-species stands in wet, boggy spots with blackened, peaty soils. It’s not uncommon to find bigleaf maple on wet sites like creek bottoms, but both bigleaf maple and western redcedar also grow well upslope, out of the wet. Red alder is a pioneer and relatively short-lived—it invades abandoned roads and clear-cuts and can form stands as dense as dog hair. It partners with nitrogen-fixing bacteria that live inside its root cells so has a ready supply of fertilizer in nutrient-poor sites. Douglas-fir, grand fir, and western white pine tend to be generalists that can thrive on an array of sites away from creek bottoms and wetlands.
Designing a planting is a little like arranging places at a holiday dinner with family and friends. Everyone has their quirks and strengths and weaknesses; you need to know them and place people accordingly. For example, we’ve been planting red alders close to Sitka spruce ever since one of our boys found a study showing that once alders age and begin to die back, Sitkas get a huge shot in the roots from the nitrogen in the soil.
But we’ve been fooled, too. The 6 acres of gently sloping land on the east side of Tarboo Creek was pastured for a hundred years and left empty for thirty. It was an upland, sunny location with a southwest exposure. So we planted a mix of trees dominated by Douglas-fir, grand fir, and western redcedar. But in 2 acres of this area, in the northernmost tip of the property, virtually nothing survived.
At first we thought the problem was the crew of local schoolchildren and families that had done much of the planting. Using kid power was the brainchild of Northwest Watershed Institute, who realized that plant-a-thons would be not only a great community event but also potentially a fundraiser for education. nwi staff recruited two local grade schools, and the kids started selling cards promising that they would plant a tree in return for a small donation. In recent years as many as four schools and five hundred students and parents have been involved in a single planting season. Plant-a-thons have now reforested much of the Tarboo Creek floodplain and touched lives in unforeseen ways. When our dog Cam was dying of stomach cancer and got so sick she couldn’t stand anymore, a veterinarian in nearby Port Hadlock kindly put her down. The vet had no idea we were involved in the restoration project, but a week later we got a card from her office saying a tree had been planted in Cam’s memory at a plant-a-thon near Tarboo Creek. I’ve also heard college students I didn’t know give speeches saying that their interest in the natural world started with a Tarboo Creek plant-a-thon they participated in as schoolchildren.
Our site was the first-ever plant-a-thon that nwi organized, though, and the kids and parents were new to planting. Now they are old pros—some have planted every year for ten years or more—but back then, we feared operator error in the patch where all the trees had died.
Failure like this isn’t all that unusual. The first season that the Leopold family planted pines on their property in Wisconsin, the spring of 1936, one of the Dust Bowl–era droughts killed everything—three thousand saplings. The family did what good people do in a situation like that: they replanted.
Our little 2-acre tree cemetery became known as the Dead Zone. We replanted the next year, and the year after that. Still no success. By now it was clear that it wasn’t operator error at all—the plant-a-thoners had done just fine. Something else was going on.
Finally, late one winter, I figured it out. I was trying to find a few saplings among the hundreds of dead bones sticking up when I noticed that the bases of the needleless trees were standing in water. The site was upslope but sopping wet. I recalled having an easy time digging holes for new saplings in the area because the soil was so fine and homogenous. When I also remembered that the soil was sticky, a light finally went on. It was clay.
Clay consists of particles that are a fraction of the size of sand grains. Because they are small and light, they stay suspended in moving water long after sands and gravels fall out. Clay particles are routinely carried long distances by r
ainwater or glacial melt before being deposited in low spots when the water finally slows down. Many of the five-story-high bluffs above Puget Sound consist of clay, deposited at the bottom of a lake that formed during glacial times.
The Dead Zone started just 30 yards from the creek bottom and was on a west-facing 10-percent slope. But for some reason, there was a clay lens close to the surface. Because clay particles pack so tightly that there is almost no space between them and water can’t percolate through, the clay layer was acting like a swimming pool liner, creating what hydrologists call a perched wetland. The Dead Zone was dead because the trees were drowning.
A few years later, the biologists in charge of restoring the Elwha River floodplain in Washington began facing the same problem, writ extremely large. The Elwha has headwaters in the center of the Olympic Mountains and flows north to the Strait of Juan de Fuca. (The Olympics are among the only mountain ranges in the world with radial drainage, meaning rivers flow out from them in all directions.) In 2011 the National Park Service began removing two dams across the Elwha in what qualifies as the largest dam removal project in history. The hope is that a restored river might again host runs of Chinook salmon with individuals as large as those recorded in predam days: 100 pounds.
When the dams were down and the lakes behind them had drained into a free-flowing river channel, biologists were left with hundreds of acres of bare clay—formed from sediments that used to be carried down to the Pacific but that had settled out of the quiet lake water. Some parts of the clay beds were dotted with old-growth stumps, but the original forest soils were buried. The clay would be waterlogged in winter and baked as hard as pottery in summer. The plantings were designed appropriately but had to contend with yet another issue: elk. The Olympic Peninsula is home to a subspecies called Roosevelt elk, and when the Elwha restoration was newly planted the elk seemed to take special pleasure in going from sapling to sapling, pulling them up or browsing them down.
Saving Tarboo Creek Page 4