Global warming could have impacts right here in the Rogue Valley, boosting the number and size of wildfires, harming salmon and reducing the snowpack people rely on for drinking water and irrigation.

Experts in global warming and other fields outlined some of the consequences of higher temperatures during a weekend conference for journalists at Southern Oregon University.

The Intergovernmental Panel on Climate Change, founded by the United Nations and The World Meteorological Organization, has reported evidence that the Earth's warming is "unequivocal." Additionally, the Nobel Prize-winning panel said there is a greater than 90 percent likelihood that the rise in temperatures since 1950 can be attributed to human-caused emissions of heat-trapping gases.

"The warming of the climate is unequivocal. This is very strong language coming from scientists," Philip Mote, Washington's state climatologist and lead author of portions of the IPCC's report, said at the conference.

Although scientific consensus on global warming is relatively recent, the concept that increased emissions of gases could trap the sun's heat is not new. Back in 1896, Swedish scientist, Svante Arrhenius, theorized that higher carbon dioxide levels would boost global temperatures. His ballpark estimates of the impacts are close to today's measurements. Living in chilly Switzerland, the scientist thought global warming would be beneficial, Mote said.

"Now we know there are some downsides," he said.

Global warming hits home

While images of polar bears struggling to navigate across melting ice sheets makes for compelling television footage, the effect is to make the problem of global warming seem distant.

The Earth's poles experience more dramatic changes than more temperate zones. As white snow and ice that reflect the sun's rays melt, the darker colors of the land and ocean absorb more heat.

But temperatures are rising in the Rogue Valley as well.

From 1930 to 2005, the average January temperature in Medford rose four degrees, said Roger Hamilton, director of the Climate Leadership Initiative's Local Community Climate Program and a Klamath County rancher.

From 1950 to 2000, the number of major wildfires has increased on every continent except Antarctica, he said.

The fires that have burned hundreds of square miles around San Diego cannot be directly attributed to global warming. Instead, people need to look at larger trends, Mote said.

Even without global warming, humans have altered fire trends. People developed effective firefighting skills in the 1930s and suppressed fires for decades.

Crowded, weakened forests are now going up in flames, leading to a spike in acres burned that exceeds figures from the 1920s, Mote said.

Global warming could lead to warmer, dryer summers and increased fires in low elevation forests &

the same forests that surround Ashland and the Rogue Valley, he said.

The number of acres burned in the United States could increase by 50 percent by the 2020s. Acres burned could jump 100 percent by the 2040s, said Bob Doppelt, a member of Gov. Ted Kulongoski's Climate Change Integration Group.

The Oregon Department of Forestry, the U.S. Forest Service and the federal Bureau of Land Management spend $60 million to $196 million on fire control costs. That figure could rise above $90 million up to $293 million in the 2020s, and between $130 million and $391 million by the 2040s, Doppelt said.

Even as summer's grow hotter, cold winter weather that kills pine beetle larvae and other pests will decrease, causing outbreaks and further stressing forests, Mote said.

Impact on agriculture

Pathogens that live in the soil and pests that attack agricultural crops &

including the Rogue Valley's orchard fruits and wine grapes &

would also survive warmer winter temperatures, said Greg Jones, a professor and research climatologist at SOU who is also an internationally known consultant for the wine industry.

Global warming has mixed impacts on agriculture. A longer growing season, fewer frost events and carbon dioxide fertilization could boost production, he said.

But the effect on the quality of crops is unknown. For example, a tomato could be larger but the taste could suffer, he said.

Cold weather makes buds on orchard trees more viable and fruitful. Warmer temperatures can lead to overripe fruit and reduce yields because trees are under stress. Many crops quickly acclimatize to mild weather, losing their hardiness to withstand freezing weather when it does strike, Jones said.

For the wine industry in Oregon, prime production areas could shift to higher elevations and to the coasts. The Willamette Valley, which has built a reputation on cooler varietals like pinot noir, could suffer. Meanwhile, Southern Oregon vineyards are generally planted with warm and hot-weather varietals, he said.

"Southern Oregon is better situated than the Willamette Valley," Jones said.

As temperatures rise, vineyard owners may have to replace cool varietals with ones that thrive in warmer temperatures. That would involve cutting back vines to leave the root stock, and then grafting on more suitable types. The grafted vines would take five years to mature and produce wine grapes, he said.

To avoid devastating losses from those years of lost production, vineyard owners could graft 10 to 25 percent of vines per year and gradually rotate out cool-weather varietals, he advised.

Southern Oregon wouldn't escape global warming's impact on irrigation and drinking water.

Snow is already melting sooner, with streams in the Northwest hitting their peak spring flows an average of 10 days earlier, Mote said.

Less water will be flowing down from mountains in the summer, when irrigation and drinking water reservoirs begin to run low, he said.

In some years, the city of Ashland has had to impose water-use restrictions on residents and businesses because of low water levels in Reeder Reservoir, which is fed by Ashland Creek. Plans are still being formulated for a multi-million dollar piping system to connect to Medford and augment the town's limited water supply.

Warmer winter temperatures would increase the risk of rain-on-snow events that can trigger abrupt melting and floods, Doppelt said.

In 1997, a rain-on-snow event led to major flooding when Ashland Creek overflowed its banks and tore through Lithia Park and the downtown. Other areas of town were damaged from smaller creeks.

Doppelt noted that 50 percent of Oregonians live in snow transition basins where slight warming can turn snowfall into rain.

Struggling salmon hit hard

Salmon in the ocean wait for cool temperatures to begin their epic migrations up rivers and streams to spawn.

"Spawners will wait and not migrate up rivers if it's too warm," Mote said.

If fish runs do go up rivers, their eggs may be less secure.

Increasing late winter and spring floods would scour salmon eggs from their river gravel beds, Mote said.

Hot summers and dropping water levels would further stress fish.

Even people who don't care about salmon would be impacted by their plight.

Oregon gets 43 percent of its electricity from hydroelectric dams, said Bob Therkelsen, an energy consultant and SOU adjunct professor.

Hydro power could become more expensive as river and reservoir levels drop in the summer, but electricity demand for air conditioners rises. Compounding the problem, dams may have to increase summer water releases to aid fish, Doppelt said.

"The Power Planning Council thinks the Endangered Species Act may have the biggest impact on cost because of requirements for summer flows," he said.

The price of dealing with damage caused by global warming, preparing and adapting to changed weather and &

if humanity chooses &

working to reduce greenhouse gas emissions will be borne by everybody, Doppelt said.

"The range of costs will eventually affect every aspect of society," he said.

Staff writer can be reached at 479-8199 or vlaldous@yahoo.com. To post a comment, visit .