NW Climate Science Digest

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

California snowpack won't recover until 2019

Margulis, S. A., G. Cortés, M. Girotto, L. S. Huning, D. Li, and M. Durand (2016), Characterizing the extreme 2015 snowpack deficit in the Sierra Nevada (USA) and the implications for drought recovery, Geophys. Res. Lett., 43, doi:10.1002/2016GL068520

A recent paper in Geophysical Research Letters supports an argument that state hydrologists have been making for months: It will take several years to recover from the recent four-year water shortage. The continually low snowpack in the Sierra Nevada created a large water deficit that may not be recovered until 2019. In April 2015, California’s water content hit 5% of its annual average, the lowest it has been in 500 years. Forecasters thought that a strong 2015 El Nino would alleviate some of the “water stress” the state was under, but winter ended up having close to normal conditions. On March 30, the water content held by the state’s snowpack was 87% of normal – a vast improvement from 5% the year prior, but still below average.

Trends and sensitivities of low streamflow extremes to discharge timing and magnitude in Pacific Northwest mountain streams

Kormos, P. R., Luce, C. H., Wenger, S. J., & Berghuijs, W. R. (2016). Trends and sensitivities of low streamflow extremes to discharge timing and magnitude in Pacific Northwest mountain streams. Water Resources Research Water Resour. Res. doi:10.1002/2015wr018125

Scientists from the U.S. Forest Service developed a method for examining the various forces affecting the magnitude of low streamflow extremes in the Pacific Northwest. Historical data shows that low streamflow extremes are dominantly controlled by amount of precipitation rather than air temperatures that change the timing of snowmelt. However, changes in precipitation due to climate change are not well understood. In this recently published study, Kormos et. al used mean streamflow as a proxy for precipitation and streamflow timing as a proxy for air temperature in order to quantify their relative influences on low streamflow extremes for 42 stream gauges. These methods showed that winter low flow metrics are weakly tied to both mean annual streamflow (precipitation forces) and center of timing (air temperature forces).

Detectability of change in winter precipitation within mountain landscapes: Spatial patterns and uncertainty

Silverman, N. L., & Maneta, M. P. (2016). Detectability of change in winter precipitation within mountain landscapes: Spatial patterns and uncertainty. Water Resources Research Water Resour. Res. doi:10.1002/2014wr016493

A study was conducted in the mountainous terrain of Western Montana to determine the minimum amount of change in winter precipitation that is necessary to be detected. To gather data, the researchers looked at historic regional climate model simulations and ground observations and compared the values to the best estimates of precipitation. The study found that approximately 65% of the significant increases in winter precipitation are undetectable. Areas where change can be detected are largely controlled by topographic features. Elevation and aspect are key characteristics that determine whether or not changes in winter precipitation can be detected. The study also found that undetected increases in winter precipitation at high elevation will likely remain as snow under climate change scenarios. This means that there is potential for these areas to offset snowpack loss at lower elevations and alleviate the effects of climate change on water resources.

Climate change impact on the roles of temperature and precipitation in western U.S. snowpack variability

Scalzitti, J., Strong, C., & Kochanski, A. (2016). Climate change impact on the roles of temperature and precipitation in western U.S. snowpack variability. Geophys. Res. Lett. Geophysical Research Letters, 43(10), 5361-5369. doi:10.1002/2016gl068798

In this recently published study, atmospheric scientists from the University of Utah examined the impact of temperature and precipitation change on spring snowpack variability across the western United States. The authors conducted a 26-year historical dynamical downscaling simulation and a simulation of future climate change. They found that the negative correlation between spring snowpack and temperature weakens linearly with elevation. They also found that the correlation between spring snowpack and precipitation increases exponentially with elevation. The historical simulation showed that there is a range of threshold elevations (1580–2181 m) across six mountainous regions, above which precipitation is the main driver of snowpack variability and below which temperature is the main driver. Under a moderate end-of-century climate change scenario, these thresholds were seen to increase by 191 to 432 m.

Arid Ecosystems

Development of Soil Moisture Drought Index to Characterize Droughts

Sohrabi, M., Ryu, J., Abatzoglou, J., and Tracy, J. (2015). "Development of Soil Moisture Drought Index to Characterize Droughts." J. Hydrol. Eng., 10.1061/(ASCE)HE.1943-5584.0001213, 04015025.

Scientists from the University of Idaho recently published a report on a newly developed drought index called the “soil moisture drought index (SODI)”. Developed in order to characterize droughts, the index is based on the amount of water required to attain soil moisture at field capacity. SODI captures variations of precipitation, temperature, and soil moisture over time. Three widely used drought indices, including the standardized precipitation index (SPI), the standardized precipitation evapotranspiration index (SPEI), and the self-calibrated palmer drought index (sc-PDSI) were compared to the SODI along with local hydrological variables such as streamflow, reservoir storage, and groundwater level. Results indicated that SODI reacts more to changes in precipitation and temperature than SPI and SPEI, and overall outperformed the existing indices due to its ability to detect and quantify the extended severe droughts associated with climate variability and change. The authors concluded that SODI will add momentum to build a case toward the use of soil moisture information for drought analysis in a changing environment.

Recent Desiccation of Western Great Basin Saline Lakes

Moore, J.N. 2016. Recent desiccation of Western Great Basin Saline Lakes: Lessons from Lake Abert, Oregon, U.S.A. Science of the Total Environment 554, 142–154. http://dx.doi.org/10.1016/j.scitotenv.2016.02.161

Johnnie Moore, a geoscientist from the University of Montana, recently published results from a study examining the drivers of saline lake desiccation in the Western Great Basin. Lake Abert in southern Oregon has exhibited large scale desiccation in recent years, and was nearly dry in 2014 and 2015. This desiccation has resulted in the decline of brine shrimp and brine fly populations, consequently eliminating shorebird habitat. Using Lake Abert as a case study, Moore compiled Landsat images to construct a 65-year-long time series of the lake’s changes in volume and salinity. From this time series, Moore was able to quantify a “natural” hydrologic budget for the watershed and compare this to the current conditions of the saline lake. Natural conditions were defined to include every current input and output except for upstream human withdrawal. Moore found that, under natural conditions and even during the last two years of major drought, Lake Abert’s volume and salinity would be within normal range and the current environment would still be habitable for brine shrimp and fly populations. Findings from this study conclude that withdrawal of water for direct human use has drastically exacerbated the imbalance between natural runoff and evaporation during periods of drought. Moore emphasizes the need for an “environmental water budget” to offset this imbalance and restore the critical habitat for migratory shorebirds.

Could rising CO2 levels help plants withstand drought?

Lem, P. (2016, June 7). Could rising CO2 levels help plants withstand drought? Greenwire. Retrieved from http://www.eenews.net/climatewire/stories/1060038395/search?keyword=Could rising CO2 levels help plants withstand drought?

Global drying may not be as extensive as some models predict, according to a recent study. Carbon dioxide helps plants become hardier against drought, and the effects of drying could be counteracted by plants using less water. While the plants’ water source is expected to decrease as warmer global climates cause more arid conditions in many areas, rising atmospheric CO2 could also allow plants to close their pores more often and preserve more water.  Water saved by plants potentially means more water available for human and animal consumption. "As a result of this slight, but important increased availability of water in the soil, future droughts may be less frequent and less intense than many past studies have predicted," according to a statement from USGS.

Biodiversity/Species and Ecosystem Response

Native Olympia oysters more resilient to ocean acidification

Waldbusser, G. G., Gray, M. W., Hales, B., Langdon, C. J., Haley, B. A., Gimenez, I., Smith, S. R., Brunner, E. L. and Hutchinson, G. 2016. Slow shell building, a possible trait for resistance to the effects of acute ocean acidification. Journal of Limnology and Oceanography. doi:10.1002/lno.10348

In this recently published study, scientists from Oregon State University found support for the “kinetic-energetic hypothesis,” which posits that rapid shell growth (calcification), limited energy reserves, and more exposed calcification surfaces are traits that make mollusks more vulnerable to ocean acidification. The Olympia oyster exhibits slow embryo development relative to broadcast spawning mollusks and so presents an appropriate species to test the kinetic-energetic hypothesis. In this study, George Waldbusser and colleagues examined the success of pre-developed Olympia oysters in various pH conditions. The study found that the species showed no acute negative response to acidification treatments, thus supporting the current hypothesis. According to an interview with Waldbusser, it is possible that farmers could breed the slow-growing trait as a way of increasing the resilience of commercial species, like the Pacific oyster.

Climate and Weather Reports and Services

Earth’s climate may not warm as quickly as expected, suggest new cloud studies

Wogan, T. (2016). Earth’s climate may not warm as quickly as expected, suggest new cloud studies. Science. doi:10.1126/science.aag0567

“Clouds need to condense around small particles called aerosols to form, and human aerosol pollution—primarily in the form of sulfuric acid—has made for cloudier skies. Scientists have generally assumed Earth’s ancient skies were much sunnier than they are now. But today, three new studies show how naturally emitted gases from trees can also form the seed particles for clouds. The results not only point to a cloudier past, but they also indicate a potentially cooler future: If Earth’s climate is less sensitive to rising carbon dioxide (CO2) levels, as the study suggests, future temperatures may not rise as quickly as predicted.”

Coastal/Marine Ecosystems, Ocean Acidification, Sea Level Rise

Declining calcification of the California mussel

Pfister CA, Roy K, Wootton JT, McCoy SJ, Paine RT, Suchanek TH, Sanford E. 2016. Historical baselines and the future of shell calcification for a foundation species in a changing ocean. Proceedings of the Royal Society of London B 283: 20160392. http://dx.doi.org/10.1098/rspb.2016.0392

Evolutionary biologist Catherine Pfister and colleagues recently published a study examining historical changes in shell thickness of the California mussel (Mytilus californianus). The authors compared shell thickness of living mussel populations to that of archival collections and previous studies at two sites along the Washington coast, Tatoosh Island and Sand Point. The study found that shells of M. californianus in Washington State are significantly thinner today compared with conspecific individuals in middens dating from 1000 to 2500 years BP. Additionally, results from Tatoosh Island showed that total shell thickness and thickness per shell length were significantly lower in modern shells compared with archived shells from the 1970s. The authors identified ocean acidification, or the declining of ocean pH due to increased marine intake of carbon dioxide, as the likely explanation for these findings.


Modeling postglacial vegetation dynamics of temperate forests on the Olympic Peninsula (WA, USA) with special regard to snowpack:

Schwörer, C., Fisher, D. M., Gavin, D. G., Temperli, C., & Bartlein, P. (2016, May 16). Ng postglacial vegetation dynamics of temperate forests on the Olympic Peninsula (WA, USA) with special regard to snowpack. Climatic Change, 1-16. doi:10.​1007/​s10584-016-1696-z

“Past and future forest composition and distribution in temperate mountain ranges is strongly influenced by temperature and snowpack. LANDCLIM, a spatially explicit, dynamic vegetation model, was used to simulate forest dynamics for the last 16,000 years and compared the simulation results to pollen and macrofossil records at five sites on the Olympic Peninsula (Washington, USA). To address the hydrological effects of climate-driven variations in snowpack on simulated forest dynamics, a simple snow accumulation-and-melt module was added to the vegetation model and compared simulations with and without the module. LANDCLIM produced realistic present-day species composition with respect to elevation and precipitation gradients. Over the last 16,000 years, simulations driven by transient climate data from an atmosphere-ocean general circulation model (AOGCM) and by a chironomid-based temperature reconstruction captured Late-glacial to Late Holocene transitions in forest communities. Overall, the reconstruction-driven vegetation simulations matched observed vegetation changes better than the AOGCM-driven simulations. This study also indicates that forest composition is very sensitive to snowpack-mediated changes in soil moisture. Simulations without the snow module showed a strong effect of snowpack on key bioclimatic variables and species composition at higher elevations. A projected upward shift of the snow line and a decrease in snowpack might lead to drastic changes in mountain forests composition and even a shift to dry meadows due to insufficient moisture availability in shallow alpine soils.”

Land Use

Lessons from California: water conservation saved energy and cut greenhouse gas emissions

A study in California found that reductions in urban water use saved significant amounts of electricity and reduced greenhouse gas emissions. During the course of an emergency conservation program that stretched from June 2015 through February 2016, energy savings from water conservation totaled 922,543 megawatt-hours — enough to power 135,000 homes for a year. Energy savings from water conservation could likely be even higher than calculated because the study didn’t look at the electricity used to dispose of and treat water once it leaves homes and factories.  In response to winter rains and snows, California Governor Jerry Brown, has reduced emergency drought regulations in favor of less aggressive but longer term conservation standards. From June 1, 2015, through April 2016, the water conservation program saved more than 423 billion gallons of water, leaving resources stored underground or in reservoirs.

Antibiotics may give cows gas, contribute to climate change

Perkins, S. (2016, May 24). Antibiotics may give cows gas, contribute to climate change. Science. doi:10.1126/science.aaf5745

A new study suggests that providing antibiotics to cows may boost greenhouse emissions. Researchers looked at the effect of a 3-day treatment of tetracycline, a commonly used antibiotic, on the amount of methane generated in cattle manure. Over the course of the experiment, emissions of planet-warming methane from the dung of antibiotic-dosed cows were, on average, 80% higher than those from the manure of untreated cattle. The increase may be the result of more methane-producing microorganisms called archaea in the digestive systems of treated cattle due to the suppression of antibiotic-susceptible bacteria, the team suggests. The findings are the first to discuss increased greenhouse gas emissions due to antibiotic use.

Special Reports / Announcements

Emerging La Niña likely to end streak of record-warm years

According to the National Oceanic and Atmospheric Association, sea surface temperatures in the Pacific have cooled in the past few weeks due to the arrival of La Niña. As this cool phase may offer temporary relief from the record-breaking warm temperatures in 2014 and 2015, scientists will use this period as an opportunity to distinguish between natural and anthropogenic climate forces. Read more about the impacts of the ENSO cycle.

Taking Action

Scientists quickly turn power plant emissions into stone

Matter, J. M., Stute, M., Snaebjornsdottir, S. O., Oelkers, E. H., Gislason, S. R., Aradottir, E. S., Broecker, W. S. (2016). Rapid carbon mineralization for permanent disposal of anthropogenic carbon dioxide emissions. Science, 352(6291), 1312-1314. doi:10.1126/science.aad8132

“Carbon capture and storage (CCS) provides a solution toward decarbonization of the global economy. The success of this solution depends on the ability to safely and permanently store CO2. This study demonstrates for the first time the permanent disposal of CO2 as environmentally benign carbonate minerals in basaltic rocks. The study found that over 95% of the CO2 injected into the CarbFix site in Iceland was mineralized to carbonate minerals in less than 2 years. This result contrasts with the common view that the immobilization of CO2 as carbonate minerals within geologic reservoirs takes several hundreds to thousands of years. The study results show that the safe long-term storage of anthropogenic CO2 emissions through mineralization can be far faster than previously postulated.”

Tribal and Indigenous Peoples Matters

First Nations communities suffering ‘more intense’ impact of climate change, secret briefings say

According to reporting by the Vancouver Sun, “Briefings to Canada’s indigenous affairs minister warn that natural disasters are increasing in number and severity, disproportionately affecting remote reserve communities… The First Nations communities are at greater risk of emergencies, suffering 'more intense' impact, with climate change causing 'extreme weather' in the north.”