NW Climate Science Digest

Aquatic Resources, Stream Flow, Hydrology in the Western U.S.

Evaluating drought indices for tracking interannual streamflow variability in the PNW

John T. Abatzoglou, Renaud Barbero, Jacob W. Wolf, and Zachary A. Holden, 2014: Tracking Interannual Streamflow Variability with Drought Indices in the U.S. Pacific Northwest. J. Hydrometeor, 15, 1900–1912. doi: http://dx.doi.org/10.1175/JHM-D-13-0167.1

This study examines various indices and models used for monitoring interannual streamflow variability in the Pacific Northwest. Standardized precipitation index, standardized precipitation evapotranspiration index (SPEI), Palmer drought severity index, and water balance runoff (WBR) model output were correlated to water-year runoff for 21 unregulated drainage basins in the Pacific Northwest. Indices calculated using high-resolution PRISM climate surfaces explained 10-15% percent more variance in streamflow than metrics derived from coarser-resolution datasets. The paper addresses various ways to monitor hydro-climactic variables at local and regional scales and enables resource managers, landowners, and planners to see the additional benefit of using higher spatial resolution climate layers to account for the complex topography of the PNW.

Hydrological effects of forest transpiration loss in bark beetle-impacted watersheds

Bearup, L.A., Maxwell, R.A., Clow, D.W., and McCray, J.E. 2014. Hydrological effects of forest transpiration loss in bark beetle-impacted watersheds, Nature Climate Change 4, 481-486. doi: http://www.dx.doi.org/10.1038/nclimate2198

The mountain pine beetle infestation of the Rocky Mountains has resulted in unprecedented tree death across North America. Researchers analyzed contributions to streamflow over time and space to investigate the potential for increased groundwater inputs resulting from hydrological change following the mountain pine beetle infestation. Results of this study in Rocky Mountain National Park show that on average, groundwater fractions remain higher after infestation even when including the assumption that interannual differences in snow water equivalent translate directly to less streamflow. Additionally, results indicated that forest transpiration decreased after trees infected with the mountain pine beetle died. Understanding the impacts of mountain pine beetle infestation on the hydrological cycle provides necessary understanding for water resource management in mountain pine beetle infested forests. 

Biodiversity/Species and Ecosystem Response

Addressing and adapting to the current warming trend in the PNW

Raymond, Crystal L.; Peterson, David L.; Rochefort, Regina M., eds. 2014. Climate change vulnerability and adaptation in the North Cascades region, Washington. Gen. Tech. Rep. PNW-GTR-892. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 279 p. http://www.treesearch.fs.fed.us/pubs/47131

Over the past two years the North Cascadia Adaptation Partnership (NCAP) worked with stakeholder groups within the North Cascade region to recognize regional climate change issues relevant to resource management, and to address adaptation strategies that will help facilitate a transition into a warmer climate. In the PNW a 2.1 °C temperature increase is expected by the 2040s and a 3.8 °C increase by the 2080s. The warming climate will have significant regional effects for both aquatic and terrestrial ecosystems. Some of the effects of a warmer climate discussed in this paper include flooding, fluctuation in seasonal flows, reduction in fish habitat suitability, and fluctuations in productivity/growth in tree species. While adapting to and dealing with the aforementioned effects of altered climate is a challenge, this paper addresses adaptation strategies that increase the potential for the PNW ecosystems to remain functional in future decades. 

Pacific salmon challenged by warming waters

Muñoz, N.J., Farrell, A.P., Heath, J.W., and Neff, B.D. 2014. Adaptive potential of a Pacific salmon challenged by climate change. Nature Climate Change. doi: http://dx.doi.org/10.1038/nclimate2473

This paper investigates the ability of Chinook salmon to adapt to warming water temperatures caused by climate change. The researchers found that the salmon developed cardiac irregularities in waters warmer than 24.5°C. Based on an average warming projection, researchers predict a 17% chance of “catastrophic” loss in the population by 2100, with this chance increasing to 98% in a maximum warming scenario. A constraint on the upper limit of thermal tolerance highlights the susceptibility of Pacific salmon populations to projected increases in temperature.

Congressional rider threatens iconic grouse species protection

Congress is finalizing an omnibus appropriations bill for the fiscal year of 2015 containing a rider that would temporarily prohibit listing the Greater Sage-Grouse as an endangered species and would impede conservation efforts for the Gunnison Sage-Grouse. Historically, riders accepted into appropriations bills are long-lasting and, in many cases, permanent. The grouse rider undercuts major conservation efforts, and jeopardizes species recovery. 

A review of conservation buffer distance estimates for the Greater Sage-Grouse

Manier, D.J., Bowen, Z.H., Brooks, M.L., Casazza, M.L., Coates, P.S., Deibert, P.A., Hanser, S.E., and Johnson, D.H. 2014. Conservation buffer distance estimates for Greater Sage-Grouse—A review: U.S. Geological Survey Open-File Report 2014–1239, 14 p.doi: http://dx.doi.org/10.3133/ofr20141239

This report summarizes a collection of published scientific studies that evaluated the effects of anthropogenic activities and infrastructure on Greater Sage-Grouse populations. It is intended to serve as a reference for land managers and others who aim to establish buffer distances around sage-grouse habitats. While the report does not propose management recommendations, it does provide summaries, interpretations, and citations of management recommendations from the scientific literature. Due to inherent variation in ecosystems, habitats, and populations, there is no one-size-fits-all solution for population buffer distance. Therefore, the report presents buffer distance values for six categories of different land use or disturbance categories commonly found in land-use plants.

Climate and Weather Reports and Services

Temperature records occur in clusters

Abatzoglou, J.T., and R. Barbero. 2014. Observed and projected changes in absolute temperature records across the contiguous United States, Geophysical Research Letters, 41, 6501–6508. doi: http://dx.doi.org/10.1002/2014GL061441

Researchers analyzed the chronology of absolute highest and lowest temperature records for minimum and maximum temperatures across the US using climate station data from 1920 to 2013. Many of the absolute highest temperature records were set during the 1930s, during the most severe drought of the twentieth century. Additionally, during the same time period over 25% of the weather stations recorded their highest minimum daily temperature. The authors then used 20 global climate models to analyze the evolution of absolute temperature records through 2049 under a high-end greenhouse gas scenario. These models predicted that high temperatures are expected to increase and low temperatures are also expected to increase. The projected novel temperature records may necessitate adaptation measures to minimize damage to ecosystems. 

Why two-degrees Celsius?

The Intergovernmental Panel on Climate Change (IPCC) states that we must keep the average global temperature increase since the pre-industrial era below 2 °C. Why do we focus so heavily on this specific target? This target number (2 °C) was derived from the work of William Nordhaus who stated that beyond this point “the effects of global warming on society became dangerous and problematic.” This specific two-degree target became well established in the policy domain when it was toted as a potentially achievable target during talks that preceded the Kyoto Protocol. Thereafter, two degrees Celsius became known as a “tipping point”, after which ecosystems would be increasingly disrupted. Given present projection trends we are expected to reach and surpass this two-degree tipping point within just 30 years.

Where and when will we observe cloud changes due to climate warming?

Chepfer, H., V. Noel, D. Winker, and M. Chiriaco. 2014. Where and when will we observe cloud changes due to climate warming? Geophysical Research Letters, 41, doi: http://dx.doi.org/10.1002/2014GL061792

Models predict that cloud distribution will change in response to climate warming, however uncertainties in the satellite record are greater than the magnitude of the predicted effects. Authors of a recent publication in Geophysical Research Letters discussed the effects of climate change on cloud distribution. The researchers used satellite observations and model-simulated observations to detected changes in cloud distribution that were attributable to climate change. This study demonstrates that cloud vertical distribution is sensitive to climate change and that cloud radiative effect and total cloud cover are not robust signatures of climate change. 

Coastal/Marine Ecosystems, Ocean Acidification, Sea Level Rise

Global Sea Level Rise Scenarios for the United States National Climate Assessment

Global sea level rise (SLR) has been persistent over the past several decades, and the trend expected to continue though the next century. SLR poses a serious threat to the United States as more than eight million people live in regions at risk of coastal flooding, and many of the nation’s military, energy, and commerce resources lie on or in close proximity to the ocean. This report, created by NOAA’s Climate Program Office, along with contributing authors from various federal and academic science institutions, is a synthesis of SLR scientific literature and a set of plausible future SLR scenarios. The report presents four future SLR scenarios ranging from 0.2 meters to 2.0 meters by 2100. The group of scenarios serves as a set of reasonable trajectories that can be used as a starting point for assessment experts and their stakeholders to evaluate vulnerability, impacts, and adaptation strategies in the face of uncertain futures. 

Natural variations playing an important role in sea level rise:

Wendel, J. 2014. Sea levels changing in response to natural variations, Eos Trans. AGU, 95(48), 452. doi: http://dx.doi.org/10.1002/2014EO480009

Scientists have widely accepted that sea level has been rising over the past one hundred years due to anthropogenic activities that warm the planet and melt land-locked ice. If green house gas emissions continue at their current rate, models suggest that sea level rise will continue at an accelerated rate. However, despite the emphasis on anthropogenic factors as a driving force of sea level rise, Dangendorf et al. posit that natural variation could be playing a larger role in SLR than previously thought. After analyzing 138 years of tidal gauge and ocean reanalysis data the authors found that natural variation caused random and persistent sea levels changes spanning several decades. These natural variations could incorrectly be interpreted as an acceleration of the rate of sea level rise. Therefore, future sea level rise could be higher or lower than predicted levels because of deviations arising from natural variability.

Tracking U.S marine fish populations as climate changes

Developed by NOAA Fisheries and Rutgers University, OCEANADAPT is a web tool designed to provide distribution data on nearly 650 species of U.S fish and invertebrates important for commercial and recreational fishing. Marine fish and vertebrate populations are responding to changing ocean conditions by shifting their distributions northward to cooler waters. OCEANADAPT is a valuable tool for fishermen, managers, scientists, and fishing communities tracking and evaluating the distribution of marine fish and other species with changing climate and ocean conditions.

Ocean acidification threatening shellfish hatcheries

Waldbusser, G.G., Hales, B., Langdon, C.J., Haley, B.A., Schrader, P., Brunner, E.L., Gray, M.W., Miller, C.A., and Gimenez, I. 2014. Saturation-state sensitivity of marine bivalve larvae to ocean acidification. Nature Climate Change.doi: http://dx.doi.org/10.1038/nclimate2479

A recent study published in Nature Climate Change has found that the Pacific oyster and Mediterranean mussel larvae are sensitive to saturation state, and not carbon dioxide partial pressure or pH. Saturation state is a measure of how corrosive seawater is to calcium carbonate shells of calcifying organisms. Successful larval development and growth during shell formation is heavily dependent on seawater saturation state. While pH levels affect other physiological processes, the saturation state threshold will be crossed decades earlier than pH thresholds, due to the nonlinear responses of saturation state as atmospheric CO2 concentrations are increased. This study adds to the body of evidence suggesting that moderate ocean acidification impacts almost caused the complete collapse of the PNW oyster industry. 


Regional projections of the likelihood of very large wildland fires under a changing climate in the contiguous Western United States

C. Alina Cansler and Donald McKenzie 2014. Climate, fire size, and biophysical setting control fire severity and spatial pattern in the northern Cascade Range, USA. Ecological Applications 24:1037–1056. doi: http://dx.doi.org/10.1890/13-1077.1

Researchers evaluated changes in the climatic potential for very large wildfires (VLWF) across the western United States during the 21st century by using generalized linear models and downscaled climate projections for two representative concentration pathways. There was a significant increase in the potential for VLWF between contemporary climate and mid-century climate (2031-2060). The Pacific Northwest, Northern Rockies, Rocky Mountains, Eastern Great Basin, and Southwest are the regions that show the greatest increase in the probability of a VLWF over time. Determining the frequency and the seasonality of VLFW is heavily dependent on future climate space. The results and projections of this study can be used for form new fire policy and by serve as a baseline for policy and management. 

The climate-wildfire-air quality system – interactions and feedbacks

Starvos, E.N., McKenzie, D., and Larkin, N. 2014. The climate-wildfire-air quality system: interactions and feedbacks across spatial and temporal scales. WIREs Climate Change, 5:719-733. doi: http://dx.doi.org/10.1002/wcc.303

Current and predicted effects of climate warming present a challenge for protecting ecosystem services, which include air quality. Studies have demonstrated that increasing temperatures and longer periods of drought will increase the area burned by wildfire in North America. Wildfire has a significant impact on air quality in some locations, and is a contributor to pollutants of concern. The authors propose that climate, wildfire, and air quality need to be studied and defined as one system. Through synthesizing the latest research on climate, wildfire, and air-quality the authors define interactions, feedbacks, and propose a method to studying the system as a whole. Additionally, the authors discuss the larger scientific implications for studying the system as a whole.


Researchers find that as CO2 grows, trees don't

Van der Sleen, P., P. Groenendijk, M. Vlam, N. P. R. Anten, A. Boom, F. Bongers, T.L. Pons, G. Terburg & P. A. Zuidema.  2015.  No growth stimulation of tropical trees by 150 years of CO2 fertilization but water-use efficiency increased. Nature Geoscience 8, 24–28 doi:10.1038/ngeo2313

Models predicted that as atmospheric CO2 concentrations increased forests would take in more CO2 and grow, increasing their ability to mitigate global warming. However, these model predictions were called into question when an international team of scientists led by Peter van der Sleen analyzed thousands of tree rings and found no correlation between increased atmospheric CO2 concentrations and increased tree growth (evidenced in tree rings). It is probable that this study came to a different conclusion because of variations in research methods. Previous studies evaluated biomass material located in small forest plots rather than using a random sample of trees throughout a forest. Additionally, van der Sleen’s study used a long-term dataset covering 150 years whereas previous studies typically evaluated tree growth on a shorter time scale. Three possible explanations are posited to explain the absence of tree growth: (1) it is possible that rising temperatures is preventing the expected tree growth, (2) the tree’s fruits or roots did grow more, just not the tree rings, (3) there is an additional resource, outside of CO2 concentrations and water, that is limiting tree growth.

Land Use

Estimating climate change effects on net primary production of rangelands in the United States

Reeves, M.C., A.L. Moreno, and K.E. Bagne. 2014. Estimating climate change effects on net primary production of rangelands in the United States, Climatic Change, 126:429. http://dx.doi.org/10.1007/s10584-014-1235-8e

Researchers analyzed the potential effects of climate change on net primary productivity (NPP) of US rangelands from 2001 to 2100. Results show that the agricultural region in the Pacific Northwest could become more productive as a result of climate change. Rangelands of the interior west were projected to experience the greatest increase in NPP. Additionally, models predicted proportionally larger increases in NPP at higher elevations. The management implications of these projections are equivocal. The authors cite evidence suggesting that increased NPP could lead to an increase in grazing carrying capacity. However, other cited evidence suggests that increased NPP could lead to a reduction in overall carrying capacity because of other limiting factors. 

Special Reports / Announcements

Obama Administration releases final principles, requirements and guidelines for federal investments in water resources

The Obama Administration released final version of Principles, Requirements, and Guidelines (PR&G), designed to “govern how Federal agencies evaluate proposed water resource development projects.” This is the first update to the PR&G in over than thirty years. The guideline modifications improve the current approach to water resource development by evaluating and expediting projects with the greatest economic and community benefits.

Climate change indicators in the United States

The EPA has released the third edition of “Climate Change Indicators in the United States,” a report designed to help readers “understand long-term trends related to the causes and effects of climate change.” The report includes 4 new indicators: Wildfires, heating and cooling degree days, Lyme disease, and water level and temperature in the Great Lakes. All indicators included in the report are related the causes or effects of climate change, with some indicators representing trends that are more anthropogenic than others. 

Obama permanently withdraws Bristol Bay from leasing

President Obama has permanently withdrawn Alaska’s Bristol Bay, one of the world’s most valuable salmon fisheries, from future oil and gas leasing. Invoking authority from the 1953 Outer Continental Shelf Lands Act, President Obama removed the North Aleutian Basin planning area (which includes Bristol Bay) from oil and gas leasing. This withdrawal will stand until Obama or a future a president reverses it. This action was unsurprising because Obama has granted Bristol Bay temporary protection in 2010 and was set to expire in 2017. This memorandum withdraws approximately 32.5 million acres from development.

Taking Action

Climate data initiative releases ecosystem vulnerability and water resources resilience themes

The Obama Administration released two datasets as part of the Climate Data Initiative, a focal point of Obama’s Climate Action Plan. The datasets focus on “Ecosystem Vulnerability” and “Water.” Data from the Ecosystem Vulnerability hub can be used to further understand the climate change impacts on water resources, biodiversity, invasive species, the ability of our ecosystems to sequester carbon, and the frequency and extent of wildland fires. Data from the water resources resilience theme provides information that can help communities and governments develop plans and policies to ensure the provisioning of water resources in the face of climate change. 

Congress passes bill to protect over 250,000 acres of wilderness

Congress has passed the largest public lands bill in six years. In the bipartisan package over 250,000 acres of wilderness in Washington, Montana, Nevada, and Colorado will be protected, 140 miles of rivers will be protected, over a dozen national parks will be established or expanded, and hundreds of thousands of acres will be removed from mineral development. The following are examples of what the bill will protected: Hermosa Creek Special Management Area and Wilderness (Colorado), Wovoka Wilderness (Nevada), Pine Forest Range Wilderness (Nevada), Alpine Lakes Wilderness (Washington), Rocky Mountain Front Conservation Management Area and Wilderness (Montana), North Fork watershed mineral withdrawal (Montana).

Tribal and Indigenous Peoples Matters

Sauk-Suiattle reservation at risk from climate change

An assessment conducted by Natural Systems Design concluded that the Suak-Suiattle Indian Reservation is at risk from flooding and erosion. The Suak-Suiattle Reservation lies on the banks of the Suak River near Darrington, Washington. Over the next 80 years it is expected that flooding extent will increase by fifty percent and the frequency of the floods will more than double. Currently, the Tribe has no defenses in place to prevent the river from flooding into residential housing areas and Tribal offices.