COLUMBIA RIVER - Salmon and trout, coldwater fish species that get the most attention and money in the Columbia/Snake river basin - are the most vulnerable to global warming, which a new scientific report calls "unequivocal."
"Salmon habitat loss would be most severe in Oregon and Idaho with potential losses exceeding 40 percent by 2090," according to "Climate Change Impacts on Columbia River Basin Fish and Wildlife," a report released last week by the Independent Scientific Advisory Board.
"Loss of salmon habitat in Washington would be less severe, with the worst case about 22 percent loss by 2090. These estimates do not consider the associated impact of changing hydrology," according to the report's executive summary.
Bull trout, too, figure to be more cramped as warmer weather pulls up water temperatures because they require very cold, headwater streams for spawning.
"Therefore, a warming climate may disproportionately impact this species. Recent projections of the loss of habitat suitable for bull trout in the Columbia Basin as a result of climate warming range from 22 percent to 92 percent," according to the new report.
For the report the 11-member ISAB, and ad hoc member Nathan Mantua, reviewed the basic physics of the natural greenhouse effect, the role of past, present, and future human actions in altering the natural greenhouse effect, and how the resultant climate changes may affect the Columbia Basin.
"The potential impacts of these predicted climate changes on the aquatic ecosystems utilized by Columbia River salmon and other cool-water species and effects on the productivity of the salmon populations are explored, as are potential impacts on terrestrial ecosystems," according to the report. The panel also offered suggestions for bringing assumed climate change into ecosystem and salmon recovery planning and points to measures that might mitigate the warming's effects.
"Climate change needs to be more seriously considered" in planning and prioritizing fish and wildlife projects, ISAB member Bob Bilby told the Northwest Power and Conservation Council Wednesday.
The Council and NOAA Fisheries established the ISAB in 1996 to provide independent scientific advice and recommendations regarding scientific issues posed by the respective agencies on matters that relate to their fish and wildlife programs. Columbia River Basin Indian tribes were added as equal partners in the sponsorship of the ISAB in 2002.
The only way to slow the climate change progression is to reduce humans' belching of gases such as carbon dioxide, methane, and nitrous oxide and industrial chemicals into the earth's atmosphere. That fast-growing haze absorbs heat that, without the trace gases' presence, would normally be radiated back out into space.
"It did not just happen," Mantua said of the rapid increases in greenhouse gas concentrations that have coincided with the industrialization of the planet and skyrocketing motor car use.
Increased concentrations have been dramatic since the mid-20th century.
Mantua, of the University of Washington's Climate Impacts Group, said climate change projections for the coming century show a "consistent picture of wet places getting wetter and dry places getting drier."
A recent CIG effort employing 10 different models and two greenhouse gas emission scenarios displays 20 different outcomes, predicting an increased average temperature in the Northwest of from 1 to 6 degrees C, or about 11 degrees F at the top end, by 2100.
"Six degrees is an enormous change," Mantua said.
The modeling projects that the average temperature will be at the top end of its historic annual range (45-49 degrees F) by 2020, and well beyond that range by 2040.
By the 2090s, the projected rise in regional temperatures would put us "in a whole new climate." Mantua said.
The planet is already getting a taste of that potential future.
"Warming of the global climate is unequivocal," according to the report. "Evidence includes increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global mean sea level.
"Eleven of the last twelve years (1995 -2006) rank among the 12 warmest years in the instrumental record of global surface temperature (since 1850). The linear warming trend over the last 50 years (0.13 +/- 0.03 degrees C per decade) is nearly twice that for the last 100 years. The total global average temperature increase from 1850 - 1899 to 2001 - 2005 is 0.76 +/- 0.19 degrees C.
"Climate records show that the Pacific Northwest has warmed about 1.0 degree C since 1900, or about 50 percent more than the global average warming over the same period. The warming rate for the Pacific Northwest over the next century is projected to be in the range of 0.1-0.6 degrees C/decade. Projected precipitation changes for the region are relatively modest and unlikely to be distinguishable from natural variability until late in the 21st century" according to the report.
Most models project long-term increases in winter precipitation and decreases in summer precipitation in the Northwest, according to the report. The changes in temperature and precipitation will alter the snow pack, stream flow, and water quality in the Columbia Basin:
? Warmer temperatures will result in more precipitation falling as rain rather than snow.
? Snow pack will diminish, and stream flow timing will be altered.
? Peak river flows will likely increase.
? Water temperatures will continue to rise.
That rising average temperature will also push up the freezing level. Those in transition zones will get less snow, and more rain. Oregon and Washington west of the Cascades, northeast Washington, north Idaho and western Montana could be particularly affected.
The changed climate will bring a changed hydrology. Under natural, pre-dam conditions, peak flows in the Columbia at The Dalles were in early June; the lowest flows in October through April. A warmup would likely mean higher runoff from the available snowpack during late winter and early spring, and less water in the summer.
Some river basins, such as the Yakima, will be "more sensitive than the Columbia Basin as a whole" to that changing hydrology, Mantua said.
The changed hydrology and water temperature would have many potential effects.
"Earlier snowmelt and earlier, higher spring flows and warmer temperatures may cause spring chinook and steelhead yearlings to smolt and emigrate to the estuary and ocean earlier in the spring," the report says. "The early emigration coupled with a projected delay in the onset of coastal upwelling may cause the timing of ocean entry of juvenile salmonids to be suboptimal."
That could have "significant negative impacts on marine survival rates."
Energetic demands are increased at warmer temperatures, requiring increased consumption of prey both in-river and in the ocean. That could affect growth rates and survival potential, depending on food availability.
"Increases in water temperature will accelerate the rate of egg development of fall Chinook, which spawn in the mainstem of the Snake and Columbia rivers, and lead to earlier emergence at a smaller average size than historically," the report says. Smaller sized fry are more vulnerable to predators.
Increased water temperatures could also delay adult salmon migrations, stalling dam passage, increasing fallback, and sapping reserves due to increased metabolic demand.
"Increases in mortality also may be caused by fish pathogens and parasites as these organisms often do not become injurious until their host becomes thermally stressed," the report says.
"We've got to reduce greenhouses gases," Washington Councilor Larry Cassidy, who noted that the adaptability shown by salmon and steelhead in the past would be tested.
In order to slow impacts on fish and wildlife from global warming, programs such as the Council's must employ tactics old and new, Bilby said.
"Any action that can help minimize water temperatures increases or augment stream flow during summer and autumn would contribute to this end," according to the report.
Specifically, protection of cold-water refugia for migrating salmon and restoration of riparian habitats in headwater reaches should have high priority.
That may entail tried and true methods, like revegetating stream banks to provide shade, purchasing water to be left in stream and improving irrigation efficiency so less water is drawn from streams and restoring wetlands and flood plains to provide more of that refugia, Bilby said.
Such work should be targeted first in the basin's most sensitive areas.
"That is a major part of our program," Council Chair Tom Karier of Washington said of the habitat restoration work. The Council's fish and wildlife program is funded by the Bonneville Power Administration as mitigation for impacts to fish and wildlife from the construction and operation of the federal Columbia/Snake hydrosystem.
"Are there area's where it just might not be worth the investment?" Karier said, noting that in some areas there is predicted to be salmon habitat losses of as much as 50 percent.
Bilby said that in some instances that may have to be considered.
"For the Council, this report reminds us how important it is to consider all potential climate-related impacts as we devise strategies to mitigate the impacts of hydropower on fish and wildlife and prioritize actions in the future," Karier said.
Dams on the Columbia and Snake rivers could be operated in ways that reduce the potential impacts of global climate change on salmon and steelhead as well, the ISAB recommended.
"To the extent that hydrosystem operations are flexible, there are opportunities to mitigate for some climate change impacts in the mainstem, estuary and plume, because projected changes in natural runoff, even under the most extreme warming scenarios for the late 21st century, are substantially smaller than the changes caused by the development and operation of the hydrosystem in the late 20th century," according to the report.
"Possible actions that could be taken on the mainstem to address climate change impacts include:
? Flow augmentation from cool/cold water storage reservoirs. If this strategy requires addition storage capacity, careful consideration of the benefits and negative impacts of increasing the number of dams in the basin will be required.
? Use of removable surface weirs to reduce the time juvenile salmonids spend in the warm water of the dam forebays
? Reduce water temperatures in the ladders with water drawn from lower, cooler strata in the water column of the dam forebays
? Develop transportation strategies for initiating full transport of juvenile fall Chinook more focused on temperature criteria
? Evaluate the possibility of transporting immigrating adults through the lower Snake River when water temperatures reach near lethal limits in the late summer
? Expand the predator control program to introduced piscivorous species such as smallmouth and largemouth bass, walleye, and channel catfish
? Open backwater, slough, and other off-channel habitats along mainstem reservoirs and the estuary to encourage increased flow through these areas to help reduce water temperature and provide cool-water refugia."
The ISAB cites potential changes in environmental conditions that could result, including:
? Changes in species' ranges. Many species of insects, birds, and trees will move to higher elevations and more northerly latitudes if climate change and human population growth alter current habitats.
? More wildfires and insects. Drought and hot, dry weather already have contributed to an increase in wildfires and corresponding outbreaks of insects in the Columbia Basin, especially mountain pine beetle. Insect outbreaks are likely to become more common and widespread.
? Fish habitat changes. Temperature increases will render 2 percent to 7 percent of current trout habitat in the Pacific Northwest unsuitable by 2030, 5 percent to 20 percent by 2060, and 8 percent to 33 percent by 2090. Salmon and steelhead habitat may be more severely affected because those fish migrate through, or spawn in, lower, and therefore warmer areas of the region.
The ISAB report is posted on the Council's website at this location (http://www.nwcouncil.org/library/isab/isab2007-2.htm).
The Council is an agency of the states of Idaho, Montana, Oregon and Washington and is directed by the Northwest Power Act of 1980 to prepare a program to protect, mitigate and enhance fish and wildlife of the Columbia River Basin affected by hydropower dams while also assuring the region an adequate, efficient, economical and reliable power supply.
*Related Stories from the CBB Members' Archives:
?- (4/5/2007) STUDY LOOKS AT CLIMATE CHANGE IMPACTS ON SALMON RECOVERY
?- (1/12/2007) STUDY DETAILS CLIMATE CHANGE IMPACTS ON WASHINGTON STATE
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