The Climate CIRCulator is brought to you by The Pacific Northwest Climate Impacts Research Consortium (CIRC) and The Oregon Climate Change Research Institute (OCCRI).

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National Climate Assessment
Northwest Faces Scarce Water, Wildfires, Coastal Challenges in Future

The Northwest can expect temperatures to rise between 3.3 degrees and 9.7 degrees Fahrenheit by 2070 to 2090. That is among the sobering conclusions of the Third U.S. National Climate Assessment (NCA), released last month by President Barack Obama. The report — the most comprehensive and authoritative yet on climate change’s projected effects on the United States — says higher temperatures can be expected to drive earlier snowmelts, which will lead in turn to water scarcity for some Northwest communities, farms and ranches that rely on snowpack.

Climate change is expected to transform the Northwest’s forests because of disturbances, especially from insects, and more frequent and devastating wildfires, the report states. Major changes to the Northwest’s forests could be observed as early as the 2040s. Extensive vegetation shifts in the region’s subalpine forests are projected by the 2080s in the higher-emission scenarios.

Containing 30 chapters and other material, the NCA covers subjects ranging from how climate change is likely to affect U.S. agriculture and freshwater supplies to how the nation’s infrastructure and health might be affected. The report also reviews in detail the latest climate science covering U.S. regions from the Northeast to Northwest.

Climate models project that global sea levels will rise by another 1 to 4 feet by 2100. In the Northwest, sea levels will rise slightly slower due to the region’s tectonic activity, which is lifting the region’s coastline. Nonetheless, Northwest sea levels are projected to eventually exceed uplift, as they already have done in some areas. Rising sea levels will increase erosion of Northwest beaches and lead to the Pacific Ocean inundating coastal ecosystems and communities, the report concludes.

Ocean acidification also is projected to increase. Ocean acidification is the popular name for the process by which atmospheric CO2 dissolves in seawater, making the world’s oceans less basic and hence more difficult for animals such as oysters and corals to construct their calcium carbonate shells. Shell-making creatures such as the Pacific oyster are important to the region’s economy.

The NCA’s Northwest chapter draws extensively on research conducted by the region’s scientists, including several associated with CIRC, OCCRI, and the Northwest Climate Science Center. OCCRI Director Philip Mote and the University of Washington’s Amy Snover were lead authors on the NCA’s Northwest chapter, and Mote served on the NCA’s advisory committee. Last year, Mote, Snover, and OCCRI’s Meghan Dalton edited Climate Change in the Northwest, a 270-page assessment report that further details the research covered in the NCA’s Northwest chapter.

Third U.S. National Climate Assessment:
The Northwest chapter:
Climate Change in the Northwest:

One of three target plant species: Waldo rockcress, Arabis aculeolata (Greene – Brassicaceae) (©Mark Turner)

High-Elevation Vegetation
Mountain Plants Adapt to Factors Above and Below

Think of a conical mountain in a warming climate. Will plants simply move upslope to stay within their usual temperature range? It’s not that simple, an experiment in the Siskiyou Mountains of Oregon suggests.

Temperature and elevation are only part of the picture driving plants’ adaptation to warming in alpine ecosystems, Marko Spasojevic and colleagues found. A complex mix of other factors — soil chemistry, topography, plant-to-plant interactions and microclimates (the climate in a small area that may differ from the surrounding climate) — help determine plant survival in a new location, the researchers found.

For the experiment, Spasojevic’s team moved three plant species to cooler locations, i.e. to more north-facing slopes or to higher elevations, than they currently inhabit. The scientists also removed existing vegetation at some of the new sites before transplanting the target species.

Two species grew better at the cooler sites than at their original locations, especially at sites where neighboring vegetation remained, perhaps because neighboring vegetation can provide shelter from wind and cold. The higher soil organic matter naturally present at the cooler sites also improved the success of one of the transplanted species.

The authors conclude that the buffering effect of topography and microclimates can only be fully understood when considered in the context of above-ground, plant-to-plant interactions and below-ground biogeochemical processes and feedbacks. Without consideration of these effects, the survival of a species in a warmer climate may be underestimated. This study also suggests that at least some species may already be out of equilibrium with current climate conditions, and may disperse naturally soon.
Spasojevic, Marko J. et al. (2014).  Above- and Belowground Biotic Interactions facilitate Relocation of Plants into Cooler Environments. Ecology Letters, 17, 6, 700–709,

CIRC Website photos (©Joel Rogers)

Reader Survey
Your Opinion Sought

We would like to know how well the CIRCulator meets your expectations and hear your ideas for improvement. Also, there are already Northwest climate-themed newsletters produced by other entities like the North Pacific Landscape Conservation Cooperative, and we want to ensure that together our newsletters are as effective as possible. Please fill out and submit the anonymous survey at

Old growth fir forest, Douglas Fir, Noisy Creek Preserve, The Nature Conservancy, Cascade Range, Washington state (©Joel Rogers)

Forests and Climate
Warmer Summers May Mean Slower Douglas-Fir Growth

Douglas Fir is a climatically versatile and commercially valuable tree species. Although its response to climate variability and change is still uncertain, a new study suggests that as Oregon's temperature continues to rise, summer heat may limit Douglas-fir growth in the future.

In the Northwest, Douglas-fir growth is determined by interactions of temperature and soil moisture during the growing season, along with other climate variables. Science suggests that Douglas-fir growth in the Pacific Northwest is water limited, which means that both temperature and moisture consistently limit forest growth during the summer.

Researcher Peter Beedlow and colleagues examined the response of Douglas-fir growth to air temperature and soil water patterns during the growing season. They analyzed growth data collected at roughly four-week intervals from 1998 through 2009 at five mature forest stands in Oregon. One site is near the Pacific Coast, while the other four (Moose Mountain, Falls Creek, Soapgrass and Toad Creek) straddle the Cascades up to about 1,200 meters in elevation. The scientists looked at mean daily air temperature for January and July/August; average precipitation for the summer and for the year; and vapor-pressure deficit.

At four of the five sites, tree growth was equally affected by maximum daily air temperature and soil water, the study showed. At the coastal site, however, soil water was more important. Growth rates were optimal at temperatures of about 20 degrees to 25 degrees Celsius, while rates decreased at higher temperatures. At the two driest sites (Moose Mountain and Toad Creek) temperature and soil water affected growth interactively as optimal temperature dropped along with soil water.

Interactions between temperature and soil water limited growth at three of the five sites. Because July/August maximum temperatures often fall between 20 degrees and 25 degrees Celsius, the interaction of temperature and moisture limits growth at all sites when summer temperatures are above average.
Beedlow, Peter A., et al. (2103).  The Importance of Seasonal Temperature and Moisture Patterns on Growth of Douglas-fir in Western Oregon, USA. Agricultural and Forest Meteorology, 169, 174-185,

Cascade tree frog (Dr. Maureen Ryan, University of Washington)

Northwest Habitat Loss
Shrinking Ponds Put Amphibians at Risk

Northwest amphibians, from frogs to salamanders, have long evaded predation from exotic trout living in the region’s rivers by seeking refuge in nearby ponds and other shallow waterways. However, these amphibian safe havens are drying up because of climate change, a recent paper in Frontiers in Ecology and the Environment concludes.

Conservation tools that could help managers and biologists track the loss of this important amphibian habitat range from hydrologic models used in projecting stream flows to aerial and satellite imagery, which helps map wetlands, especially in remote and as yet un-surveyed areas, according to the authors. The research, funded by U.S. Fish and Wildlife Service and CIRC’s sister organization, the Department of the Interior’s Northwest Climate Science Center, is investigating how critical amphibian habitat is being affected by climate change.
For full review of the research read “Amphibians in a vise: Climate change robs frogs, salamanders of refuge” from the University of Washington’s news page, UW Today.

Ryan, Maureen E. et al. (2014). Amphibians in the Climate Vise: Loss and Restoration of Resilience of Montane Wetland Ecosystems in the Western US. Frontiers in Ecology and the Environment, 12, 232–240,

Russell Vose and colleagues' assessment of the state of knowledge regarding changes in various climate extremes (described below). The x axis refers to trend detection (i.e., how useful the data actually are for assessing historical changes). The y axis refers to the physical causes of the observed changes [i.e., how well the mechanisms driving changes are understood (and thus how extremes are expected to change in the future)]. For each axis, phenomena are assigned to one of three categories of knowledge (from less to more), and the dashed lines toward the top right imply that knowledge about the phenomena is not complete. Extremes discussed in previous workshops appear in gray text. (Click on image to enlarge.)

Extreme Weather Events
Winds, Waves and Storms Are Growing Stronger

Certain storms are getting stronger and hitting more often in the Northern Hemisphere. That is the conclusion, reported by Russell Vose and colleagues, of one workshop in a series of National Climate Assessment workshops that examined changes in extreme weather events.

Winds, waves and “extratropical” storms have increased in intensity and frequency over recent decades, the workshop found. Extratropical storms — ones that originate outside the tropics and usually move west to east across land and sea — account for most of the extreme winds from December to February along U.S. coasts, the data showed. These extratropical storms, which occasionally affect western Oregon and Washington, can carry heavy precipitation, severe icing and high winds across large swaths.

Another finding: Extreme waves on the Pacific coast appear to have increased since the 1950s, using one research approach; we note that CIRC PI Peter Ruggiero found similar results using buoy data available since the 1970s.

In one study examined for the workshop, data showed that a 25 percent increase in peak wind gusts causes almost a sevenfold increase in building damage. Another study found that insurance losses increased by 44 percent with only a 6 percent increase in the average winter gust. Coastal areas are especially at risk, as onshore winds accentuate tides and enhance storm surge, battering shorelines and damaging structures. Increasing sea levels extend the impact zone inland.

Vose, Russell S., and Coauthors, 2014: Monitoring and Understanding Changes in Extremes: Extratropical Storms, Winds, and Waves.  Bull. Amer. Meteor. Soc., 95, 377–386,

Polluting smoke from a coal-fired power plant on the shore of Lake Michigan, Gary, Indiana. (©Joel Rogers)

Climate Sensitivity
Co2 Doubling and Global Warming:
How Soon Will Scientists Know More?

Having more certainty about “climate sensitivity” is important because it could help shape climate policy, according to Nathan Urban and colleagues. “Climate sensitivity” (or “equilibrium climate sensitivity”) is the amount of global warming that will happen when atmospheric CO2 doubles, relative to preindustrial levels. (If scientists could rule out high sensitivity, then policies could be more lax; if scientists could rule out low sensitivity, then the need for aggressive policies would be clearer.)

In the three-and-a-half decades since a report on anthropogenic warming first estimated the range of climate sensitivity, many processes that contribute to that sensitivity are now much better understood, the researchers note in a recent paper that focused on scientists’ “learning rate” about climate sensitivity.

The Charney Report of the U.S. National Academy of Sciences estimated in 1979 the climate sensitivity at between 1.5 degrees and 4.5 degrees Celsius. That range is unchanged today, according to the latest assessment report of the Intergovernmental Panel on Climate Change (IPCC).

Ocean heat uptake and impacts from aerosols are two important factors in the rate at which climate sensitivity may be narrowed. That’s because the rate of warming is tempered by those other factors. The authors experimented with a simple climate model and a range of time-dependent futures for each of the factors. They found that for all reasonable estimates of ocean heat uptake and aerosol “forcing,” the range in estimated climate sensitivity will be substantially narrowed by 2050, to as little as 0.4 degrees Celsius. More rapid “learning” will occur if the climate sensitivity is low – in other words, it is more difficult to learn about high sensitivity, so if the sensitivity is high it will take longer to realize there’s a problem.

Urban, Nathan M. et al (2014).  Historical and Future Learning about Climate Sensitivity.  Geophysical Research Letters, 14, 2543-2552,

The Climate CIRCulator is brought to you by The Pacific Northwest Climate Impacts Research Consortium (CIRC). CIRC delivers science, information, and tools to decision makers responsible for the management of  resources and services in a changing climate. Our team consists of experts from Oregon State University, the University of Oregon, the University of Idaho, Boise State University, and the University of Washington. CIRC is funded by the National Oceanic and Atmospheric Administration (NOAA) and housed in the Oregon Climate Change Research Institute (OCCRI) at Oregon State University. The OCCRI brochure can be downloaded  here.
The Climate CIRCulator, May, 2014, Issue 5.
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