Climate's smoke signals.

Byline: CHRISTIAN WIHTOL Register-Guard Business Editor

SEEKING RELIEF FROM the heat in recent weeks, Oregonians have turned up the air conditioning, sipped iced drinks or headed to swimming holes.

But for Oregon's vast swaths of forests, no such cooling options exist - and therein lies a source of growing concern for scientists and others who study global climate change: the Earth's gradual heating up and its effects on woodlands.

The lack of rain and the periodic blistering heat this summer are but a taste of what may lie in store for Oregon in the decades ahead, scientists agree. And how Douglas fir and other species cope with longer, hotter summers is of huge economic and ecological importance to the state.

Will global warming be slow and mild over many decades, allowing Oregon's 27.7 million acres of privately owned tree plantations, government-owned old growth preserves and other forests to gradually adapt with minimal fuss?

Or will the warming be quicker and steeper, over just a few decades, parching Oregon forests to the point where they become drought-stressed and much more vulnerable to pest infestations and fires such as those that have swept the state this summer?

Should private and government landowners be figuring ways to diversify Western Oregon forests away from the dominant Douglas fir to see if other species fare better in the hotter climate that may lie ahead?

There's little agreement. But scientists, forestry experts and others in Oregon and worldwide say decision-makers and the public need to take climate change and its possible impacts seriously.

Politics and carbon dioxide 

U.S. politicians avoid the topic in part because scientists are unable to predict with much confidence whether the warming will occur over the next couple of decades, and to spell out exactly what will happen in specific regions, said Ron Neilson, a bioclimatologist and leading expert on climate change with the U.S. Forest Service in Corvallis.

"Most scenarios are looking out 100 years and seeing huge changes in that time frame," Neilson said. "But the fundamental question from policy-makers is, what about the near term? What about the next five, 10, 20 years?"

Some experts blame the Western forest fires this summer on a buildup of vegetation due to lack of forest thinning. But Neilson says global warming may also play a role.

He suspects the rise in carbon dioxide levels in the atmosphere over the past several decades has spurred vegetation growth rates and helped create thick stands of fire-vulnerable trees.

"What we need to impress upon (policy-makers) is that this is happening here and now and will have very significant impacts in the next one to two decades," Neilson said.

Scientists have argued for decades that carbon dioxide emissions from coal-burning power plants and gasoline-powered vehicles are causing a buildup of carbon dioxide in the atmosphere that is trapping heat and prompting the temperature to rise.

President Bush in June said nations must simply adapt to global warming. The United States, which is responsible for more than 20 percent of the world's so-called "greenhouse" gas emissions, can't afford to cut its use of carbon-based fuels, Bush said.

That sparked an outcry from environmentalists, scientists and others. Environmental groups have also lambasted the U.S. decision not to sign the Kyoto Protocol, the 1997 treaty that every other industrialized nation has signed. The treaty sets time frames for cutting carbon dioxide emissions.

Hotter, but drier? Or wetter?

For a growing army of scientists, environmentalists, forest experts and even timber industry executives, global warming has become a topic of study and debate.

In the Pacific Northwest, it will have broad effects, from heavier winter rainfall that will generate severe floods, to lower river levels in the summer, the disappearance of glaciers and the demise of ski areas, predicts Northwest Environment Watch, a Seattle-based environmental group.

Experts at Oregon State University, including Neilson, who teaches in the Forest Sciences Department, are struggling to understand the effects of global warming on trees: How are they reacting to increased carbon dioxide in the air, and how will they handle growing seasons that may start earlier and include longer, hotter, drier summers?

At issue is a complex interplay of atmospheric carbon dioxide, temperature and rainfall.

Trees use carbon dioxide to grow, so as the atmosphere's carbon dioxide level rises, trees should grow faster, scientists and forest economists agree. In the past 150 years, carbon dioxide levels in the air have risen from about 280 parts per million to about 360 parts per million.

A rise in average temperature of a few degrees will foster tree growth by creating a longer growing season. With a warmer climate, trees may begin to grow in higher elevations in the Cascades that were previously too cold, said Richard Waring, a professor at OSU's College of Forestry.

The amount and timing of rainfall is the frightening wild card, Neilson and others said.

Higher global temperatures will likely increase evaporation from the Pacific Ocean and thus increase total rainfall in the Pacific Northwest, Neilson said.

But will summers become hotter and drier, or hotter and wetter? No one knows.

Neilson said he fears a scenario in which summers are longer, hotter and drier.

"So we have trees waking up earlier in the spring and beginning to spend some of that soil moisture earlier than they would have, so that you run out of that soil moisture earlier in the summer," he said.

That would leave trees more vulnerable to drought stress, he said, and stressed trees can fall victim to insect infestations and fire.

A warmer climate may also make it easier for insects to breed and to attack trees, Waring said. A study in the Oregon Cascades suggests that long, freezing winters suppress the mountain beetle, which attacks lodgepole pine, he said, noting that at lower, warmer elevations the beetles have done extensive damage.

Douglas fir vulnerable?

Waring is a little more upbeat about the future than Neilson. Studies of 400-year-old Douglas firs in the Oregon Coast Range suggest the trees have survived decades-long stretches of both abnormally hot and abnormally cold weather, he said.

"They're likely to be able to put up with quite a bit of variation in climate," he said.

Brent Sohngen, an associate professor at Ohio State University's Department of Agricultural, Environmental and Development Economics, echoed the concerns about heat and rainfall.

"Hotter and drier (summers) definitely seem to be more negative for the Pacific Northwest," Sohngen said.

If the region's average temperature over the next 60 to 100 years rises by 2.5 degrees and rainfall increases 7 percent, forests may prosper, Sohngen said.

But if the temperature rises more steeply - say, an average of 5 degrees - the effect on trees would be severe, even if rainfall increases as much as 15 percent at the same time, he said, adding that there's only so much heat that a Douglas fir can take before it is weakened.

Sohngen puts an economist's spin on the issue: He sees climate change fostering rapid growth of forests in the Northeast and Midwest over the next 60-plus years. That will flood the market with timber and hurt traditional wood products economies such as Oregon's, he said.

In search of hardy trees

Bob Prolman, director of international affairs for Oregon's biggest private timberland owner, Weyerhaeuser Co., said the lack of specific regional predictions leaves timberland owners in a holding pattern.

Prolman said Weyerhaeuser is working with university and government institutions on studies aimed at determining the impact of climate change on forests. But because it is a "long-term horizon" problem, "it doesn't fight its way to the top" of Weyerhaeuser's priorities, he said.

On the other hand, timber industry executives are keen to learn more about global warming because it "may make a fundamental change to the industry," Prolman said. The insurance industry is one of the few sectors that has been outspoken about the need to tackle global warming, Sohngen noted.

That's because the warming is expected to raise ocean levels and increase coastal flooding and worsen storms - both big financial burdens on insurance companies.

Waring said as the climate warms, owners of industrial forestland in Western Oregon will probably try to diversify away from their longtime standby - Douglas fir - and plant more native species such as Western red cedar, hemlock, Ponderosa pine and alder to see which flourish. The more diversified a forest, the less vulnerable it is to pests, he said.

Al Lucier, a senior vice president at the National Council for Air and Stream Improvement, an association of big forest owners, said such crop experimentation is part of "forestry tradition," although it's driven by a quest for profit, not fear of global warming.

On Western Oregon's federally owned forests, the options are more limited. On most of the lands, logging has been largely banned to preserve wildlife.

"You have to watch closely what's going on in those natural systems," Neilson said. One option, he said, is to "just let them respond."

CLIMATE CHANGE INFORMATION

Intergovernmental Panel on Climate Change: Collaboration of the World Meteorological Organization and the United Nations Environment Program. Web site: www.ipcc.ch

Kyoto Protocol: Formally known as the United Nations Framework Convention on Climate Change. Web site:www.unfccc.int

U.S. Environmental Protection Agency: Web site:www.epa.gov/globalwarming

Pew Center on Global Climate Change: Nonprofit, nonpartisan group formed in 1998 by the Pew Charitable Trusts. Web site: www.pewclimate.org

Environmental Defense: Advocacy group that works with industry on climate change issues. Web site: www.environmentaldefense.org

CAPTION(S):

Associated Press Scientists suspect the rise in carbon dioxide levels over the past decades has spurred growth rates and helped create thick stands of fire-vulnerable trees, such as these burning in the Siskiyous north of Kerby.