Ali Bay -- East Oregonian Publishing Group The forests of the Northwest, like this stand in El Dorado County, Calif., may be vulnerable to global climate changes.
Second of three parts A SPECIAL REPORT: Forests and crops struggle to beat the heat
By PHIL WRIGHT East Oregonian Publishing Group
Global climate change is affecting everything that grows. In the first of this week's three-part series, the focus was on the impacts on salmon, oysters and other water critters.
Today the emphasis is on forests and crops of the Pacific Northwest.
With fishing, the forest products industry has driven the economy of the North Coast region. And, like salmon, the health of the forests already reflects the overall health of the region.
Scientists are worried that the region's forests are changing, while the warmer temperatures also increase the risk of catastrophic fires in the Northwest.
Using the words "global warming" can make the effects of increasing temperatures and decreasing snowpack seem removed. But climatologists and meteorologists working in the Pacific Northwest know climate change is happening, here, in our backyard.
Philip Mote is Washington's state climatologist and research scientist with the Climate Impacts Group (CIG) at Washington State University. The interdisciplinary research group is studying the impacts of natural climate variability and global climate change on the Pacific Northwest.
"First of all, temperature records over the 20th century show that warming in the Pacific Northwest is 1.5 degrees Fahrenheit. That mirrors global warming for the same period," Mote said.
He also said the kind of climate change now happening "appears to be unprecedented," as evidenced by tree rings and glacial ice, and global warming in the second half of the 20th century is strongly linked to greenhouse gases.
However, Mote said on a regional scale it's not yet possible to verify the connection between warming and greenhouse gases.
"But that seems to be the likely explanation," he added.
So what about those cycles?
Mote said the perennial question is, "How do we know it's not just a natural cycle causing the warming?"
He explained the same natural factors that were present before fail to explain the recent warming. "We can identify the natural cycles," he said. "When we factor them all in they can't explain the amount of climate change."
In general, the CIG attributes about two-thirds of climate change to human interaction, and the remaining third because of natural events, such as volcanism.
Kyle Dittmer, a hydrologist and meteorologist at the Columbia River Inter-Tribal Fish Commission in Portland, said a study conducted by the American Meteorological Society replicated observed temperatures across the earth during the last 100 years with greenhouse gases and natural causes.
The study's findings closely matched the observed record.
Mote said the scientific community has written dozens to hundreds of papers on the issue, and the consensus among practicing climatologist is humans are "partly" to "entirely" responsible for global warming in the last 50 years.
Even the skeptics...
Even skeptical climatologists, Mote said, will acknowledge that greenhouse gas emissions over the next 50 years will cause global warming.
"It's virtually impossible to find someone who will say 'Odds are 50-50 it will heat up or cool down.'"
Mote said the range of answers come in how much it could heat up and how fast it could happen. He explained the roles of greenhouse gases are identified with some uncertainty in predicting where they will go in the next 20 to 50 years. But about half a degree Fahrenheit per decade seems to be the middle-of-the-road projection from climate models.
"In terms of ecological health, that half a degree per decade means the most likely response is something we can't yet anticipate," Mote said.
Trees under scrutiny
Jeremy Littell is a doctoral candidate and, like Mote, a research scientist with the CIG. He's been working on understanding how climate change affects forests in the Blue Mountains of Oregon. He explained how trees see climate change.
"What we are talking about is the degree to which a tree is susceptible to climate change," Littell said.
For those trees that have access to more water, such as those rooted next to lakes and streams or a wet place without a lot of sunshine, are "buffered" from climate change more than trees that are rooted in more open, drier land.
For example, Littell said in the southwestern United States, trees living in the low tree line elevation are already living in a marginal area. Add years of drought to the mix and warmer temperatures, and those trees become more vulnerable to environmental changes.
The most vulnerable
While Northwest trees are not as vulnerable, Littell said scientists are asking which trees do face problems.
"Plants see precipitation and temperatures as two parts of a single equation," Littell said. For trees, hotter temperatures equal a need for more water.
Trees that have less snow and a longer spring will have a longer growing season. But as temperatures rise, trees have to expend more water to deal with those increases. And for trees, water availability limits growth.
Littell explained high temperatures have exacerbated the drought in the Pacific Northwest during the last five years. Tree rings reveal the drought during the last five years in the Pacific Northwest is as bad as or worse than anything experienced since the mid-19th century.
The drought gets worse in magnitude farther east. In Glacier National Park, the conditions are comparable to the Dust Bowl drought during the 1930s.
Littell also explained that La Niña and El Niño play a role in the Pacific Northwest's climate. In a La Niña event, there tends to be cooler and wetter winters, with abundant snowpack at high elevations. In El Niño, residents observe the opposite, and the impacts in the summer are not as significant.
In the Blue Mountains of Eastern Oregon, there is an "important relationship between fire and El Niño," Littell said.
El Niño can mean more fire.
Fire is a four-letter word
But more important than either El Niño or La Niña is the Pacific Decadal Oscillation, or PDO.
"The Pacific Decadal Oscillation is actually similar to El Niño, as it derives from changing conditions that occur in the Pacific Ocean," Littell explained.
But whereas El Niño and La Niña are relatively short lived, say 18 months once about every seven years, the PDO is decades long. Just how much it matters has yet to be determined.
"We only have 100 years of observations that are really strong," he said, thus we only have a few recorded PDO cycles.
Dittmer explained the PDO experiences rapid "phase changes" of just a few months every 20 to 30 years, where it flips from generally cooler, wetter weather to warmer and drier weather.
The last phase change was 1998. In about 2020, the PDO will flip back to the warm side, creating warmer ocean conditions and accelerating climate changes on land.
Dittmer said as yet, no one knows how to forecast the PDO, and we still have a long way to go to figure out what makes it tick, let alone why it changes phases.
Why it is crucial
Littell said from a tree's perspective, the PDO is important because it has a large effect on water supply and fire.
And while it's generally true that big fire years correspond to warm and dry seasons, the whole situation is a bit more complicated.
Littell said once a fire has started, how big it gets is a function of both the climate before the fire and the weather at the time of the fire.
A drier climate before a fire means the fuel load is drier and more flammable. In arid ecosystems that have shrub and grasslands, the fire scenario becomes more complicated still, because wet seasons don't mean less fire, but an increased fuel load. More water, then, combined with better growing conditions make a recipe for fire.
"You have to get that combination of wet and dry," Littell said. The Biscuit Fire was the largest fire in North America in 2002, and it had help from both the weather that season and from years of drought. Thus, to bring a fire to an area of certain size, the right conditions are needed.
In forests, there is always enough fuel load for a fire, Littell said, but the right conditions of water, heat and dryness must be present.
"We're busy trying to understand how much water is required."
Unfortunately, climate models don't predict changes in precipitation. They also don't answer all the questions scientists have about climate change.
Littell said for climate models, five to 10 years is a time period they can deal with well.
"We have a grasp on five to 10 years," a period that is marked with variability in the climate system by such things as El Niño. Climate models also do well with 100 years out.
Littell said that for five to 10 years we should see similar condition as in the past, and 100 years out we can say temperatures will exceed temperatures of today. But that period from about 20 to 50 years, with leeway on either side, is the big mystery.
Add to this mix the topography of the Pacific Northwest, with the Cascade Mountains dominating the landscape and keeping much of Oregon and Washington in a large rain shadow.
Dittmer explained that lands below 4,000 feet in elevation face accelerated climate change, while lands at altitudes higher than 4,000 experience climate change at a decelerated rate.
For Pacific Northwest tribes, those elevation numbers matter.
The Nez Perce tribes have 54 percent of their land at about 4,000 feet, Dittmer said, and the Warm Springs have about 31 percent above, while the Yakama and Umatilla only have 14 to 16 percent of land above that magic mark.
He said the Yakama and Umatilla tribes are at the highest risk for feeling the effects of climate change.
Just how well forests deal with climate change may come down to "resilience," which Littell defines as the capacity of the ecosystem to bounce back after an event.
For example, how long after a fire a particular watershed will be impaired for delivering of water or impaired in delivering productive habitat is quantified by resilience.
But as with so much in science, resilience is difficult to quantify.
Littell also warns the term "bounce back" may be loaded, because it can be defined by someone's values. How people see forests can play into the idea of resilience. For example, is a forest more resilient if it can be used for recreation or for timber sales?
But forest resilience means more than either. It encompasses the whole health of the ecosystem, from trees to water to carbon storage to the land's carrying capacity for animals to water supply.
Just how resilient the forests and rivers of the Pacific Northwest are or could be to climate change may be up to us.
Large scale needed
Dittmer suggests the Columbia River system needs an enormous government project - akin in scope to the Manhattan Project - to help keep the waters healthy and cool. And while Littell said there are "several layers of resilience" in the Blue Mountains, keeping fuel structures in place without conducting thinning could produce a formula for fire.
Mote said ultimately, the "take-home message" from climate change is that humans are inducing it, especially during the latter half of the 20th century.
Hurricanes like Wilma, Katrina and Stan, Mote said, are a "huge wake-up call."
Phil Wright is a writer for the East Oregonian
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