NW Climate Science Digest

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

Projecting precipitation throughout the 21st century over North America

Wang, J. and V.R. Kotamarthi 2015. High-resolution dynamically downscaled projections of precipitation in the mid and late 21st century over North America. Earth’s Future, 3, doi:10.1002/2015EF000304.

In this new study, high spatial resolution (12 km) simulations were performed using the Weather Research and Forecasting (WRF) model. The purpose of the simulations was to explore mean and extreme precipitation projections for the mid to late 21st century. Because of the higher spatial resolution of the simulations, the study allowed for resolving precipitation in ways that had not previously been possible (such as over mountain ranges). The authors found that among 10 subregions they studied, the Pacific Northwest showed the greatest increase in the number of days each year when extreme precipitation occurs. This was the case for both emissions scenarios studied, RCP 4.5 and RCP 8.5, but there was a higher increase in the number of days with extreme precipitation for RCP 8.5.  

Artificial amplification of warming trends across the mountains of the western United States

Oyler, J.W., Dobrowski, S.Z. Ballantyne, A.P., Klene, A.E., Running, S.W. 2015. Artificial amplification of warming trends across the mountains of the western United States. Geophysical Research Letters 42, 153-161. doi:10.1002/2014GL062803.

A new study suggests that elevation dependent warming may not be occurring as is suggested by observational data. Observations from the mountain climate station network in the Western United States suggest that some higher elevation areas are warming faster than lower elevation areas. This study evaluates temperature observations from the climate network sites and finds that the extreme warming observed at higher elevations is a result of systematic artifacts and not climatic conditions. The authors find that climate data that is widely used for model simulations propagate these temperature trends, which impacts the ability for studies to accurately model climate change impacts in mountainous parts of the Western US.

Groundwater slowly being depleted in the United States

Konikow, L.F. 2015. Long-Term Groundwater Depletion in the United States. Groundwater 53, 1, 2-9.

Between 1900 – 2008, the volume of groundwater stored below the United States decreased by almost 1000 cubic kilometers. The areas with the highest amount of storage depletion include the High Plains aquifer the Mississippi Embayment section of the Gulf Coastal Plain aquifer system, and the Central Valley in California. The rate of depletion has accelerated since 2000. Leonard Konikow, the author of the study, introduces a new parameter for studying groundwater depletion, ‘depletion intensity’, to understand how storage changes are occurring geographically. He found that the Central Valley in California had the highest depletion intensity. Groundwater depletion can have a wide range of harmful effects, including reduced well yields, reduced base flow to springs, streams and other surface water bodies, and loss of wetlands. It is also responsible for sea level rise, and Konikow found that groundwater depletion in the United States could explain 1.4% of observed sea level rise that occurred during the study period.

Using Air Temperature to Model Stream Warming

Caldwell, P., Segura, C., Gull, S., Sun, G., McNulty, S.G., Sandercock, M., Boggs J., James, M. 2015. Short-term stream water temperature observations permit rapid assessment of potential climate change impacts. Hydrological Processes 29, 2196-2211.

A new U.S. Forest Service Southern Research Station study demonstrates how long-term historic air temperature data can be used in conjunction with short-term stream temperature data to project future warming in streams. Peter Caldwell, a research hydrologist at the Coweeta Hydrologic Laboratory, led the study. Caldwell and his colleagues showed how only 18 months of stream temperature observations could be used to explain variability in stream temperature for up to 37 years. They used these findings to model historical stream temperatures at 61 sites in the Southeastern United States from 1961 to 2010, and then used these models to project future temperatures from 2011 through 2060. They found that stream temperatures had already increased during the historical period, and those streams located in the Appalachian ecoregion were predicted to be most vulnerable to climate change. These findings were seen as a significant breakthrough, as before it was very difficult to project long-term climate change impacts on stream temperature.

Commentary on Heightened Risk of Drought due to Climate Change

Mann, M.E. and P.H. Gleick 2015. Climate change and California drought in the 21st century. PNAS 112, 13, 3858-3859. doi: 10.1073/pnas.1503667112

In this commentary piece, Pacific Institute Director Peter Gleick and Pennsylvania State University Meteorologist Michael Mann discuss the state of current literature on drought and climate science. They discuss a new study published in PNAS by Diffenbaugh et al., which shows accumulating evidence that climate change is influencing the frequency, magnitude and duration of drought in California. An increasing number of dry years along with warm years raise the risk of drought, despite the lack of a strong trend in precipitation. These results point to the significance of warming temperatures to changing the availability of water and increasing drought intensity. It is important to note, however, as the authors do, that this is not uncontested. A number of recent studies (some of which focused on a lack of trend in precipitation) concluded that a link between ocean temperatures and drought could not yet be established. Part of the debate, however, has occurred because there are many ways in which drought can be defined. A drought can be meteorological, hydrological, agricultural, and/or socioeconomic. Other parts of the debate stem from attribution. Some studies argue that low levels of precipitation cannot be tied to climate change, while others argue that while this may be true, the low levels of precipitation are caused by an unusually strong ‘atmospheric ridge’ in the Western United States, which was most likely stronger due to climate change.

Arid Ecosystems

How Projections for Drier Terrestrial Areas Vary Between Climate Models

Scheff, J. and D.M.W. Frierson. 2015. Terrestrial aridity and Its Response to Greenhouse Warming across CMIP5 Climate Models. Journal of Climate, 28. DOI: 10.1175/JCLI-D-14-00480.1

The degree of aridity of a terrestrial climate is typically evaluated by using the relative magnitudes of precipitation (P) and potential evapotranspiration (PET). This study uses an aridity index of P/PET and looks at how this index varies in 16 different global climate models from CMIP5. The authors find that the index agrees between climate models in most of Eurasia and North Africa, but disagree dramatically in large areas of North America, Sub-Saharan Africa and South Asia. The same areas can be represented as semiarid-to-arid or quite humid, depending on the climate model. This is in contrast to the climate adage “wet areas get wetter, dry areas get drier”.

Biodiversity/Species and Ecosystem Response

Maintaining species by translocating them to locations where climate is suitable

Thomas. 2011. Translocation of species, climate change, and the end of trying to recreate past ecological communities. Trends in Ecology & Evolution 26:216-221. 

University of York researcher Chris Thomas argues that the only viable way to deal with species at high risk from climate impacts is to relocate them to other areas where the climate is suitable. Many species are unable to relocate themselves for a variety of factors (slow dispersal rates, unable to surmount human and natural obstacles, etc.), and these species need to be intentionally relocated to areas where they can survive. For example, some species are endemic to the summit of a particular mountain range, and as temperatures warm, the temperature may no longer be cold enough for them to survive, thus they would need to be relocated. Thomas argues that this is the most effective way to reduce the extinction rates that are projected due to climate change impacts, thus it is currently the most viable method of reducing biodiversity losses.

Marine travellers best able to adapt to warming waters

Sunday, J.M; Pecl, G.T.; Frusher, S.; Hobday, A.J.; Hill, N.; Holbrook, N.J.; Edgar, G.J.; Stuart-Smith, R.; Barrett, N.; Wernberg, T.; Watson, R.A.; Smale, D.A.; Fulton, E.A.; Slawinski, D.; Feng, M.; Radford, B.T.; Thompson, P.A.; Bates, A.E. 2015. Species traits and climate velocity explain geographic range shifts in an ocean-warming hotspot. Ecology Letters. Doi: 10.1111/ele.12474

Due to extensive dam removal and habitat restoration, this year has brought record runs of juvenile Coho salmon in Goldsborough Creek. The previous record was 61,000 Coho, and this year 113,000 juveniles were counted. This was a major success; fifteen years ago, the US Army Corps of Engineers removed a dam on Goldsborough, and since then, the Squaxin Island Tribe has worked closely with other partners to improve the habitat for fish. The dam removal was significant, as it opened up access to wetlands. This is essential for the lifecycle of Coho salmon, which spend an additional year in freshwater before going out to sea (unlike most species of salmon). According to Andy Whitener, natural resources director for the Squaxin Island Tribe, this year’s record points to the importance of habitat for salmon, and to the potential for habitat restoration projects to lead to dramatic improvements.




Marine travellers best able to adapt to warming waters: Researchers at the University of Southampton and an international team of biodiversity experts found that marine species with smaller migration ranges are at high risk due to climate change, while marine species with large migration ranges face smaller risks due to being more adaptable. University of British Columbia biodiversity research Jennifer Sunday, lead author of the study, showed how marine species with higher adult mobility demonstrated the ability to adapt to warming oceans by migrating to cooler waters. These same species are typically habitat generalists and were at equilibrium with their environments, allowing them to respond to warming temperatures by shifting their migration patterns. The study site was located off of Australia’s east coast, where the ocean has been warming at four times the global average rate. Marine species have been observed further south than ever before as a result of this. Species observed included the tiger shark, short-tail stingray and barren-forming urchin, along with a number of notoriously invasive omnivore fish species.

Feasibility of Reintroducing Native Fish: Case of Bull Trout

Dunham J., Gallo, K., Shively D., Allen, C., Goehring, B. 2011. Assessing the feasibility of native fish reintroductions: A framework applied to threatened bull trout. North American Journal of Fisheries Management 31:106-111. 

In contrast to the previous article, this study shows how relocating threatened species can be problematic without sufficient attention to feasibility prior to implementation. The authors develop a feasibility framework that should be used to assess a relocation project prior to implementing it. The framework has two basic components: the ability for new habitats to support reintroduction and the potential for available donor populations in the new habitat to support reintroduction. The authors then applied this framework to the reintroduction of bull trout into the Clackamas River in Oregon.

Taking stock of the assisted migration debate

Hewitt, N., Klenk, N, Smith, A.L., Bazely, D.R., Yan, N., Wood, S., MacLellan, J.I., Lipsig-Mumme, C., Henriques, I. 2011. Taking stock of the assisted migration debate. Biological Conservation. DOI: 10.1016/j.biocon.2011.04.031

A study from 2011 evaluates the academic and policy conversations around assisted migration for species most at risk from climate change impacts. Assisted migration involves the intentional relocation of species outside of their historic ranges of migration in order to mitigate losses of biodiversity that have already occurred or are anticipated to occur. The authors conducted a meta-analysis of the literature on assisted migration and found a general lack of biophysical research on the topic. For the debate to be well informed, or for proposed policies to be actionable, there must be a sufficient number of case studies and more general scientific studies that look at the potential impacts of migration on species behavior and biodiversity. The authors recommended further research as well as more extensive academic and policy conversations on the topic.

Climate and Weather Reports and Services

State of the Climate Report for 2014 Released

The American Meteorological Society has released its State of the Climate Report for 2014. Key findings from the report include: 1) greenhouse gas concentrations continued to rise, reaching historic high values; 2) 2014 was the warmest year on record; 3) the tropical Pacific Ocean is moving toward El Nino Southern Oscillation conditions; 4) sea surface temperatures reached a record high; 5) global average sea level rose to a record high; 6) sea ice extent in the Antarctic reached a record high (that is not a typo!); 7) the number of tropical cyclones was well above the historical yearly average.

Weather becoming more conducive to wildfires

Jolly, W.M., Cochrane, M.A., Freeborn, P.H., Holden, Z.A., Brown, T.J., Williamson, G.J., Bowman, D.M.J.S. 2015. Climate-induced variations in global wildfire danger from 1979 to 2013. Nature Communications 6, 7537. doi:10.1038/ncomms8537

A new study argues that fire risks across the planet are rising as a result of climate change. Wildfire risk may be partially due to a decreasing ability of land and vegetation to extract carbon from the atmosphere and thus partially offset greenhouse gas emissions. As a result, wildfires are acting as a positive feedback – in other words, fires are getting worse because of climate change, while also making climate change worse. Matt Jolly, lead author of the study and a researcher with the U.S. Forest Service’s Fire Sciences Laboratory in Missoula, Montana, found that the duration of weather most conducive to fires has increased by 18.7% between 1979 to 2013. Jolly also found that the area burned increased as well.

NASA: California “Rain Debt” Equal to Average Full Year of Precipitation

Savtchenko, A.K., Huffman, A., Vollmer B. 2015. Assessment of Precipitation Anomalies in California Using TRMM and MERRA data. Journal of Geophysical Research: Atmospheres. 10.1002/2015JD023573

A new NASA study concluded that California has accumulated a debt of around 20 inches of precipitation from 2012 through 2015. This is approximately the amount of precipitation that typically falls in the state in a given year. Between 20-50 percent of California’s precipitation comes from atmospheric rivers, which move over the Pacific Ocean and are responsible for precipitation falling in others of the West Coast as well. The study authors attribute the majority of the precipitation debt to a high-pressure system in the atmosphere over the eastern Pacific Ocean that has prevented the formation of atmospheric rivers since 2011.

Climate Prediction Center Releases New Report on El Nino

The Climate Prediction Center has released a new report on the El Nino Southern Oscillation. The report issues an ‘El Nino Advisory’, stating ‘El Nino conditions are present’, ‘Positive equatorial sea surface temperature (SST) anomalies continue across most of the Pacific Ocean’ and that ‘There is a greater than 90% chance that El Nino will continue through Northern Hemisphere winter 2015-16, and around an 80% chance it will last through early spring 2016.”

Coastal/Marine Ecosystems, Ocean Acidification, Sea Level Rise

Ocean acidification may cause dramatic changes to phytoplankton

Dutkiewicz, S., Jeffrey Morris, J., Follows, M.J., Scott, J., Levitan, O., Dyhrman, S.T., Berman-Frank, I. 2015. Impact of ocean acidification on the structure of future phytoplankton communities. Nature Climate Change. Doi: 10.1038/nclimate2722

The uptake of carbon dioxide in the oceans has resulted in a drop of the global average pH from 8.2 to 8.1. By 2100, it is projected to drop further to around 7.8, which is significantly lower than any pH levels seen anywhere in open ocean marine communities around the world. The authors of this study show how ocean acidification by 2100 is projected to affect phytoplankton. Phytoplankton species are projected to exhibit a wide range of responses: some will die out, while others will flourish. Thus the balance of plankton species will be fundamentally altered. Some species will even grow faster than previously, while others will be significantly harmed, perhaps going extinct. Warming temperatures will also significantly affect the locations of phytoplankton. Many species will shift toward the poles as the planet warms. However, the most significant changes will occur from ocean acidification.

New Study on Sea Level Rise Points to Much Higher Projections Than Before

Hansen, J., Sato, M., Hearty, P., Ruedy, R., Kelley, M., Masson-Delmotte, V., Russell, G., Tselioudis, G., Cao, J., Velicogna, I., Kandiano, E., von Schuckmann, K., Kharecha, P., Legrande, A.N., Bauer, M., Lo, K.-W. 2015. Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 degrees C global warming is highly dangerous. Atmos. Chem. Phys. Discuss., 15, 20059-20179.


A new study by acclaimed NASA climate scientist James Hansen and colleagues claims that sea level rise will occur much more rapidly than forecast by the Intergovernmental Panel on Climate Change. Hansen and colleagues project a sea level rise of 5 – 9 meters in 50, 100 or 200 years if fossil fuel emissions continue on a ‘business-as-usual’ course (meaning that emissions as they are now would continue in the future). The rate of sea level rise would be accelerated by parts of the Antarctica and Greenland ice sheets melting, and this melting would bring about a number of climate change ‘feedbacks’, which would in turn increase the rate of melting. However, this study has generated considerable controversy and criticism. Other prominent climate scientists, such as Kevin Trenberth of the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, have strongly criticized the study, arguing that Hansen and colleagues made too many assumptions and extrapolations for the study to be taken seriously. However, the IPCC has been criticized in the past for making overly conservative projections, including for sea level rise. Greg Holland, also at NCAR, argues that the actual amount of sea level rise that will occur is probably somewhere between the amount projected by this study and the IPCC.


Area burned in the western United States unaffected by recent mountain pine beetle outbreaks

Hart, S.J., Schoennagel, T., Veblen, T.T., Chapman, T.B. 2015. Area burned in the western United States is unaffected by recent mountain pine beetle outbreaks. PNAS 112, 14, 4375-4380.

Mountain pine beetles have been a serious scourge in the Western US, leading to the death of pine trees across 71,000 cubic kilometers of forestland since the mid-1990s. As a result, it has been widely perceived that an abundance of dead fuels from the death of the pine trees might exacerbate fire behavior and lead to a wider area being burned. The authors of the study examined the effects of beetle outbreaks during the three peak years of wildfire activity since 2002 in the Western US and found that the effect was negligible. Although both fires and beetle outbreaks have increased due to warming temperatures, the occurrence of one does not seem to reinforce occurrence of the other.

Dry Days Bring Ferocious Start to Fire Season

Record-breaking drought this summer has set off a number of expensive wildfires this summer across the Western United States. Although wildfires used to be predominantly confined to range lands, this summer has brought wildfires even in the rain forests of the Olympic Peninsula, which is one of the wettest regions of the world. The drought has penetrated as far north as Alaska, where 399 fires burned in June, which is twice the number recorded in 2004, the state’s worst recorded fire year. Previously, fires in Alaska had burned tundra, but this year fires destroyed or damaged hundreds of homes. Projections of the nationwide cost of fighting this year’s wildfires are around $2.1 billion. In the Pacific Northwest, recent fires in and near Walla Walla, WA and Wenatchee, WA have already devastated homes and crops. With the current El Nino projections, bleak prospects are ahead – drier temperatures for most of the Pacific Northwest.


Can forests rebound from severe drought

Anderegg, W.R.L., Schwalm, C., Biondi, F., Camarero, J.J., Koch, G., Litvak, M., Ogle, K., Shaw, J.D., Shevliakova, E., Williams, A.P., Wolf, A., Ziaco, E., Pacala, S. 2015. Pervasive drought legacies in forest ecosystems and their implications for carbon cycle models. Science 349, no. 6247, 528-532. DOI: 10.1126/science.aab1833

A new study questions whether or not forests can recover from extended drought periods. The study suggests that trees can take years to go back to normal growth after experiencing a drought. Lead author William Anderegg found that trees took an average of two to four years to recover from drought, with two exceptions: trees in California and the Mediterranean actually grow more quickly after a drought. This could be explained by the dominance of oak forests in these regions. Instances of this have already occurred, and the Western US has been particularly hard hit in terms of tree mortality, according to Anderegg. Restoring the natural density of trees could be an important step in the right direction for forests in the Western US.

Land Use

Impact of climate change and land use changes on national parks

Martin, M.V., Heald, C.L., Lamarque, J.-F., Tilmes, S., Emmons, L.K., Schichtel, B.A. 2015. How emissions, climate, and land use change will impact mid-century air quality over the United States: a focus on effects at national parks. Atmos. Chem. Phys. 15, 2805-2823. doi:10.5194/acp-15-2805-2015

A new study looks at the impact of air quality between the present and a 2050 future period and quantifies effects of air quality projections on national parks and wilderness areas. The authors find that if emissions occur as projected in RCP 4.5 and 8.5 scenarios, air quality will improve significantly across the US. However, this improvement will occur unevenly. In the western US, national parks such as Yellowstone may not achieve target visibility conditions. Moreover, climate-driven fires may be a significant issue for air quality, and particularly visibility, for parks such as Crater Lake National Park in Oregon. Results suggest that the US National Park Service may need to develop air quality management plans to further mitigate air pollution.

Special Reports / Announcements

$2 Million Wendy Schmidt Ocean Health XPRIZE Announced

Sunburst Sensors, a team of chemists and engineers from Montana, won the $2 million dollar Wendy Schmidt Ocean Health XPRIZE, a global competition that aims to incentivize breakthroughs in pH sensor technology in order to measure the acidification of oceans. Sunburst Sensors is a small business in Missoula, Montana that develops chemical sensors for marine and freshwater applications. To win the prize, they developed two new breakthrough sensors a spectrophotometric process that uses a sample of ocean water, mixes it with purified dyes, and then shines a laser on the water to determine the pH level. The sensor demonstrated accuracy in both coastal and deep-ocean environments up to a depth of 3,000 meters.

Expanded West Coast Guide to Olympia Oyster Restoration and Conservation

NOAA and a number of other organizations have released a new guide on oyster populations and restoration along the West Coast. The guide covers the entire geographic range of the Olympia oyster, from Baja California to British Columbia. It discusses important environmental conditions that affect the Olympia oyster and identifies areas at risk due to low population sizes or unreliable recruitment. The most common stressors were sedimentation and predation.

Taking Action

New National Research Council fast-track study on extreme weather events

The Board on Atmospheric Sciences and Climate of the National Research Council has announced a new fast-track study on extreme weather events. Specifically, the study examines attributing extreme weather events to anthropogenic induced climate change versus natural variability.

State Has Legal Obligation to Protect Climate

In March of 2015, a group of lawyers, professors and judges from around the world released the Oslo Principles on Global Climate Change Obligations, which stated that an international agreement to cut greenhouse gas emissions was not necessary to compel governments to reduce emissions. Instead, governments are required to do so based on existing human rights and a combination of environmental and tort laws, and a failure to enact such laws will cause serious harm to citizens and the earth. This was the precursor to last month’s order, when King County Superior Court Judge Hollis Hill ordered the Washington Department of Ecology to reconsider a petition that was filed in 2014. The petition called for a reduction in carbon dioxide emissions to ‘protect the climate by considering the best available science when setting emission reduction goals’. In Washington, the state’s Clean Air Act is the primary legal vehicle for enforcing air quality.

Tribal and Indigenous Peoples Matters

Coastal Alaska natives face high shoreline erosion

Gibbs, A.E. and Richmond, B.M. 2015. National assessment of shoreline change – Historical shoreline change along the north coast of Alaska, U.S.-Canadian border to Icy Cape: U.S. Geological Survey Open-Fire Report 2015-1048.


Alaska is experiencing one of the highest rates of shoreline erosion in the world, according to a recent USGS study. More than a yard of coast is being washed off from the coast every year, and in extreme cases, nearly 30 yards of coast has already disappeared. Erosion is threatening Native Alaskan villages and large tracts of both Native Alaskan and federally managed land. According to a 2009 report, 86% of Alaskan native villages are suffering from erosion and flooding. There is talk of relocating some of these villages to safer areas. Coastal erosion in Alaska is due to a number of factors, including loss of Arctic sea ice, sea level rise and warming ocean temperature.

Preserving Tribal Water Rights in the West

First Peoples and Water: Water Resource Issues for Native Americans, 2015, American Water Resources Association Water Resources IMPACT 17, 4, 1-36.

The July 2015 of the American Water Resources Association’s ‘Water Resources IMPACT’ series focuses on water resources issues facing Native Americans. It highlights the issue of preserving water rights for tribes as water shortages grow in Western river basins and discusses the hydrologic impacts of climate change on Native American water rights. According to First Peoples Worldwide, water rights are the fastest growing risk for indigenous peoples around the world, particularly in water-stressed areas.

Building Resilience in Vulnerable Communities

The White House is releasing a progress report that highlights some of the actions taken by the Administration to support the Task Force’s recommendations. The Task Force in question is the State, Local, and Tribal Leaders Task Force on Climate Preparedness and Resilience, which was established in 2013 as part of the Climate Action Plan. Some of these actions include: 1) the Bureau of Indian Affairs is announcing $11.8 million in Tribal Climate Preparedness Grants to support tribes in preparing for climate change impacts, 2) increasing energy security in Native American tribes, 3) hosting a webinar series through the Minorities in Energy initiative to discuss regional impacts of climate change on minority and tribal communities.