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Climate Assessment: Columbia River Basin ‘Ill-Equipped’ To Handle Shift To Earlier Snowmelt

The Northwest is facing increased risks from the decline of forest health, earlier snowmelt leading to low summer stream flows, and an array of issues facing the coastal region, according to a new climate assessment report.

“Studies are showing that snowmelt is occurring earlier and earlier and that is leading to a decline in stream flows in summer,” says Oregon State University’s Phil Mote.

“Northwest forests are facing a huge increase in wildfires, disease and other disturbances that are both direct and indirect results of climate change. And coastal issues are mounting and varied, from sea-level rise and inundation to ocean acidification.”

Amy Snover, director of the University of Washington’s Climate Impacts Group and one of three editors of the 270-page report published this week by Island Press, said that “As we looked across both economic and ecological dimensions, the three that stood out were less snow, more wildfires and challenges to the coastal environment and infrastructure.”.

The report will serve as the foundation for the Pacific Northwest chapter of the forthcoming U.S. National Climate Assessment.

“Climate Change in the Northwest: Implications for Our Landscapes, Waters, and Communities” assesses the current state of knowledge about key climate impacts and consequences to various sectors and communities in the Pacific Northwest, including projected impacts on:

-- PNW climate,

-- Hydrology and water supply,

-- Coasts and oceans,

-- Forest ecosystems,

-- Agriculture,

-- Human health, and

-- Northwest Tribes

The 271-page report, which draws on the expertise of dozens of scientists and subject-matter experts within the region, was edited by Meghan Dalton and Mote (Oregon Climate Change Research Institute) and Snover (Climate Impacts Group). For more information or to download a copy of the report, go to:

http://cses.washington.edu/db/pdf/daltonetal678.pdf

The report is the first regional climate assessment in more than a decade. The document and the 1999 report were created as part of the U.S. National Climate Assessment. Washington and Oregon produced state-level reports in 2009 and 2010.

Mote said the report updates the science and addresses some new dimensions – including how climate change will affect human health and Northwest tribes that rely on natural resources.

In the Northwest, roughly 2,800 miles of coastal roads are in the 100-year flood plain, and some highways may face inundation with just 2 feet of sea-level rise. Seas are expected to rise as much as 56 inches, or nearly 5 feet, by the year 2100, the report said.

Earlier snowmelt is a concern for Northwest dams and reservoirs. The Columbia River basin has a storage capacity smaller than its annual flow volume and is “ill-equipped to handle the projected shift to earlier snowmelt … and will likely be forced to pass much of these earlier flows out of the system,” the report said.

Earlier peak stream flow may significantly reduce summer hydroelectric power production, the report concluded, and slightly increase winter power production.

The report includes information from improved climate models that suggest the Northwest will warm by 3 to 14 degrees Fahrenheit by the end of this century. For comparison, the region warmed 1.3 degrees between 1895 and 2011.

“The lower (end of the) range will only be possible if (global) greenhouse gas emissions are significantly reduced,” Mote said.

Precipitation is harder to project, according to the report, with forecasts ranging from 10 percent less rain to 18 percent more rain by 2100. Most models suggest that more precipitation will fall as rain, and earlier snowmelt will change river flow patterns.

Pinpointing the impacts of temperature and precipitation shifts on agriculture will be difficult, said co-author Sanford Eigenbrode at the University of Idaho.

“As carbon dioxide levels rise, yields will increase for some plants, and more rainfall in winter could mean wetter soils in the spring, benefitting some crops,” Eigenbrode said. “Those same conditions could adversely affect other crops. It is very difficult to say how changing climate will affect agriculture overall in the Northwest – but we can say that the availability of summer water will be a concern.”

Pests, disease and invasive species may also affect agriculture and forestry practices.

The Northwest has not yet been vulnerable to many climate-related health risks, the report noted, but future impacts of climate change are more likely to be negative than positive.

Health concerns include increased morbidity and mortality from heat-related illness, air pollution and allergenic disease, and the emergence of infectious diseases.

“In Oregon, one study showed that each 10-degree (F) increase in daily maximum temperature was associated with a nearly three-fold increase of heat-related illness,” said Jeff Bethel, an assistant professor in the College of Public Health and Human Sciences at OSU and one of the co-authors of the report. “The threshold for triggering heat-related illness – especially among the elderly – isn’t much.”

Northwest tribes may face a greater impact from climate change because of their reliance on natural resources. Fish, shellfish, game and plant species could be adversely affected by a warming climate, resulting in a multitude of impacts.

“When tribes ceded their lands and were restricted to small areas, it resulted in a loss of access to many species that lived there,” said Kathy Lynn, coordinator of the Tribal Climate Change Project at the University of Oregon and a co-author of the report. “Climate change may further reduce the abundance of resources. That carries a profound cultural significance far beyond what we can document from an economic standpoint.”

Snover said that the climate changes projected for the coming decades mean that many of the assumptions “inherent in decisions, infrastructure and policies – where to build, what to grow where, and how to manage variable water sources to meet multiple needs – will become increasingly incorrect.

“Whether the ultimate consequences of the climate impacts outlined in this report are severe or mild depends in part on how well we prepare our communities, economies and natural systems for the changes we know are coming,” Snover said.

Regional agencies can use the report’s findings to decide where to build new construction, what crops to grow where, and how to manage water resources, Snover said.

The report was funded by the National Oceanic and Atmospheric Administration, the Oregon Legislature through its support of the Oregon Climate Change Research Institute, and in-kind contributions from the authors’ institutions.

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