American West Coast Research Articles

Causes of the 2011–14 California Drought*

Abstract The causes of the California drought during November–April winters of 2011/12–2013/14 are analyzed using observations and ensemble simulations with seven atmosphere models forced by observed SSTs. Historically, dry California winters are most commonly associated with a ridge off the west coast but no obvious SST forcing. Wet winters are most commonly associated with a trough off the west coast and an El Niño event. These attributes of dry and wet winters are captured by many of the seven models. According to the models, SST forcing can explain up to a third of California winter precipitation variance. SST forcing was key to sustaining a high pressure ridge over the west coast and suppressing precipitation during the three winters. In 2011/12 this was a response to a La Niña event, whereas in 2012/13 and 2013/14 it appears related to a warm west–cool east tropical Pacific SST pattern. All models contain a mode of variability linking such tropical Pacific SST anomalies to a wave train with a ridge off the North American west coast. This mode explains less variance than ENSO and Pacific decadal variability, and its importance in 2012/13 and 2013/14 was unusual. The models from phase 5 of CMIP (CMIP5) project rising greenhouse gases to cause changes in California all-winter precipitation that are very small compared to recent drought anomalies. However, a long-term warming trend likely contributed to surface moisture deficits during the drought. As such, the precipitation deficit during the drought was dominated by natural variability, a conclusion framed by discussion of differences between observed and modeled tropical SST trends.

Causes of change in Northern Hemisphere winter meridional winds and regional hydroclimate

Improved mechanistic understanding of greenhouse gas-induced change in Northern Hemisphere atmospheric circulation reveals a tendency of models to overestimate future mid-winter rainfall along the North American west coast. A critical aspect of human-induced climate change is how it will affect precipitation around the world. Broadly speaking, warming increases atmospheric moisture holding capacity, intensifies moisture transports and makes sub-tropical dry regions drier and tropical and mid-to-high-latitude wet regions wetter1,2. Extra-tropical precipitation patterns vary strongly with longitude, however, owing to the control exerted by the storm tracks and quasi-stationary highs and lows or stationary waves. Regional precipitation change will, therefore, also depend on how these aspects of the circulation respond. Current climate models robustly predict a change in the Northern Hemisphere (NH) winter stationary wave field that brings wetting southerlies to the west coast of North America, and drying northerlies to interior southwest North America and the eastern Mediterranean3,4,5. Here we show that this change in the meridional wind field is caused by strengthened zonal mean westerlies in the sub-tropical upper troposphere, which alters the character of intermediate-scale stationary waves. Thus, a robust and easily understood model response to global warming is the prime cause of these regional wind changes. However, the majority of models probably overestimate the magnitude of this response because of biases in their climatological representation of the relevant waves, suggesting that winter season wetting of the North American west coast will be notably less than projected by the multi-model mean.

Projected wave conditions in the Eastern North Pacific under the influence of two CMIP5 climate scenarios

Hindcast and 21st century winds, simulated by General Circulation Models (GCMs), were used to drive global- and regional-scale spectral wind-wave generation models in the Pacific Ocean Basin to assess future wave conditions along the margins of the North American west coast and Hawaiian Islands. Three-hourly winds simulated by four separate GCMs were used to generate an ensemble of wave conditions for a recent historical time-period (1976–2005) and projections for the mid and latter parts of the 21st century under two radiative forcing scenarios (RCP 4.5 and RCP 8.5), as defined by the fifth phase of the Coupled Model Inter-comparison Project (CMIP5) experiments. Comparisons of results from historical simulations with wave buoy and ERA-Interim wave reanalysis data indicate acceptable model performance of wave heights, periods, and directions, giving credence to generating projections. Mean and extreme wave heights are projected to decrease along much of the North American west coast. Extreme wave heights are projected to decrease south of ∼50°N and increase to the north, whereas extreme wave periods are projected to mostly increase. Incident wave directions associated with extreme wave heights are projected to rotate clockwise at the eastern end of the Aleutian Islands and counterclockwise offshore of Southern California. Local spatial patterns of the changing wave climate are similar under the RCP 4.5 and RCP 8.5 scenarios, but stronger magnitudes of change are projected under RCP 8.5. Findings of this study are similar to previous work using CMIP3 GCMs that indicates decreasing mean and extreme wave conditions in the Eastern North Pacific, but differ from other studies with respect to magnitude and local patterns of change. This study contributes toward a larger ensemble of global and regional climate projections needed to better assess uncertainty of potential future wave climate change, and provides model boundary conditions for assessing the impacts of climate change on coastal systems.

Analysis of the Latin American west coast rainfall predictability using an ENSO index

The objective of this study was to determine the probability of occurrence of wet or dry season events, by means of estimating latitudinal profiles for the association between El Niño Southern-Oscillation and the rain-fall along the west coast of Central and South America. The analysis was performed using multinomial linear regression and multinomial logit regression models. We used monthly time series of the Pacific equatorial sea surface temperature (SST), the Niño 3.4 index, a sea level pressure index (SOI) and rainfall anomalies over a 2.5×2.5° grid along the west coast of Central and South America, for latitudes starting at 25° N through 45° S, from 1951 to 2011. We defined an ENSO index (NSO) as predictor and rainfall as response. Data was grouped into seasons and then categorized into terciles to construct 3×3 non-symmetrical three way contingency tables. As results, we generated latitudinal profiles of the predictability (association) of rainfaíl for the west coast of Central and South America, using the ENSO phases as predictor.

Spatial and Temporal Analysis of Populations of the Sudden Oak Death Pathogen in Oregon Forests.

Sudden oak death caused by the oomycete Phytophthora ramorum was first discovered in California toward the end of the 20th century and subsequently emerged on tanoak forests in Oregon before its first detection in 2001 by aerial surveys. The Oregon Department of Forestry has since monitored the epidemic and sampled symptomatic tanoak trees from 2001 to the present. Populations sampled over this period were genotyped using microsatellites and studied to infer the population genetic history. To date, only the NA1 clonal lineage is established in this region, although three lineages exist on the North American west coast. The original introduction into the Joe Hall area eventually spread to several regions: mostly north but also east and southwest. A new introduction into Hunter Creek appears to correspond to a second introduction not clustering with the early introduction. Our data are best explained by both introductions originating from nursery populations in California or Oregon and resulting from two distinct introduction events. Continued vigilance and eradication of nursery populations of P. ramorum are important to avoid further emergence and potential introduction of other clonal lineages.

English

English

Testing local and global stressor impacts on a coastal foundation species using an ecologically realistic framework.

Despite the abundance of literature on organismal responses to multiple environmental stressors, most studies have not matched the timing of experimental manipulations with the temporal pattern of stressors in nature. We test the interactive effects of diel-cycling hypoxia with both warming and decreased salinities using ecologically realistic exposures. Surprisingly, we found no evidence of negative synergistic effects on Olympia oyster growth; rather, we found only additive and opposing effects of hypoxia (detrimental) and warming (beneficial). We suspect that diel-cycling provided a temporal refuge that allowed physiological compensation. We also tested for latent effects of warming and hypoxia to low-salinity tolerance using a seasonal delay between stressor events. However, we did not find a latent effect, rather a threshold survival response to low salinity that was independent of early life-history exposure to warming or hypoxia. The absence of synergism is likely the result of stressor treatments that mirror the natural timing of environmental stressors. We provide environmental context for laboratory experimental data by examining field time series environmental data from four North American west coast estuaries and find heterogeneous environmental signals that characterize each estuary, suggesting that the potential stressor exposure to oysters will drastically differ over moderate spatial scales. This heterogeneity implies that efforts to conserve and restore oysters will require an adaptive approach that incorporates knowledge of local conditions. We conclude that studies of multiple environmental stressors can be greatly improved by integrating ecologically realistic exposure and timing of stressors found in nature with organismal life-history traits.

Evolution of regional inequality in the global shipping network

Global shipping is a backbone of the global economy, and as such, it evolves alongside the development of trade and the elaboration of commodity chains. This paper investigates the evolution of regional inequality in the global shipping network by analyzing the changing positions of world regions during the period from 2001 to 2012. This was a period of both prosperity and recession in maritime shipping. Using data on inter-regional flow connections, the positions of seventeen regions in the global shipping network are analyzed in terms of their traffic development, centrality, dominance and vulnerability. The East Asian, Northwest European and Europe Mediterranean regions have consistently held the highest positions, while East African and North African regions have held the lowest positions. By commanding the largest flows in the network, East Asia assumes a dominant position. The Australasian, North American West Coast, Northwest European and Southern African regions show an increasing dependency on East Asia. The analysis also identifies a few emerging regions that have had the highest growth rates in total traffic volume and connectivity for the studied period, namely South American North Coast, South American East Coast, West Africa, Southern Africa and West Asia. The empirical results of this paper supplement existing research on global shipping network evolution. One implication of the analysis is that the traffic growth of East Asia does not imply that, there is an equivalent improvement in its position in the global shipping network. The paper also shows that indicators from network analysis may be used to provide a more nuanced understanding of port-regional development than existing measures based solely on total traffic volume.

Toward the genetic origins of a potentially non-native population of threespine stickleback (Gasterosteus aculeatus) in Alberta

Disentangling the origin of putatively introduced/invasive species is of increasing priority in conservation biology. The presence of a previously undocumented species may be due to an undetected recent population or range expansion associated with environmental change, or due to an introduction by humans. We used molecular tools to address the origin of a population of threespine stickleback (Gasterosteus aculeatus) first identified in central Alberta, Canada in 1980 from a single lake. We characterized this inland, high elevation Alberta population in comparison to samples from five representative geographic regions worldwide, using mtDNA and nine microsatellite loci to elucidate genetic structure and estimate divergence times. We found significantly lower levels of genetic variation in the Alberta population, which could reflect either a recent colonization or periodic bottlenecks associated with winterkills. While we did find that the Alberta samples were most closely related to the North American West Coast populations, we did not uncover a putative source population. Alberta samples formed a clade in phylogenetic analyses, with divergence time estimates between the Alberta and British Columbia samples ca. 250–750 kya. The hypothesis that the Alberta population represents a natural colonization during North America’s last glacial recession could not be rejected. Collectively, these data suggest that the genetic signature of colonizing populations following introductions may be similar to populations at their range limit, contributing to difficulties establishing population origins.

Changes in Winter Atmospheric Rivers along the North American West Coast in CMIP5 Climate Models

Abstract Most extreme precipitation events that occur along the North American west coast are associated with winter atmospheric river (AR) events. Global climate models have sufficient resolution to simulate synoptic features associated with AR events, such as high values of vertically integrated water vapor transport (IVT) approaching the coast. From phase 5 of the Coupled Model Intercomparison Project (CMIP5), 10 simulations are used to identify changes in ARs impacting the west coast of North America between historical (1970–99) and end-of-century (2070–99) runs, using representative concentration pathway (RCP) 8.5. The most extreme ARs are identified in both time periods by the 99th percentile of IVT days along a north–south transect offshore of the coast. Integrated water vapor (IWV) and IVT are predicted to increase, while lower-tropospheric winds change little. Winter mean precipitation along the west coast increases by 11%–18% [from 4% to 6% (°C)−1], while precipitation on extreme IVT days increases by 15%–39% [from 5% to 19% (°C)−1]. The frequency of IVT days above the historical 99th percentile threshold increases as much as 290% by the end of this century.

How California is mobilizing boundary chains to integrate science, policy and management for changing ocean chemistry

Boundary organizations play an important role in stabilizing interactions between science and nonscience. In this paper we focus on how boundary organizations not only serve a variety of actors across a complex science-policy landscape, but also actively shape that landscape over time through process, institution building, and partnership building. Some of these partnerships are with other boundary organizations, thus forming “boundary chains”. We draw on our experiences in convening the West Coast Ocean Acidification and Hypoxia Science Panel, an interdisciplinary group of scientists working to inform regional, state and federal responses to complex ecological, social and economic issues with rapidly evolving scientific understanding. From within a landscape already populated with a diverse set of institutions and actors focused on this issue, we illustrate how the Panel itself functions simultaneously at different positions within multiple boundary chains, mobilizing a variety of boundary organization partners to deliver on its mandate. In describing these arrangements, we show how political context and a shifting balance among credibility, legitimacy, and salience as near-term priorities have shaped both the posture and focus of the panel at different stages in its evolution. This case study suggests that boundary chains are necessary in order to advance the integration of science and decision making related to a complex emerging issue, especially at the scale of the North American West Coast. We also examine the nature of links among boundary organizations, and the kinds of benefits they confer upon individual actors, and upon the network as a whole. In some cases the benefit is through increased efficiency or reduced individual transaction costs. In others, the existence of linked chains may increase the power and value of individual interactions. In considering the issues of efficiency and transaction costs, we argue that it is important to remember that boundary organizations and boundary chains tend to increase the overall number transactions in the system. Indeed, this is part of their value in linking science and decision making: they multiply and strengthen relationships in a space where interactions were previously both few and ineffective.

Dynamical and Thermodynamical Causes of Large-Scale Changes in the Hydrological Cycle over North America in Response to Global Warming*

Abstract The mechanisms of model-projected atmospheric moisture budget change across North America are examined in simulations conducted with 22 models from phase 5 of the Coupled Model Intercomparison Project. Modern-day model budgets are validated against the European Centre for Medium-Range Weather Forecasts Interim Re-Analysis. In the winter half year transient eddies converge moisture across the continent while the mean flow wets the west from central California northward and dries the southwest. In the summer half year there is widespread mean flow moisture divergence across the west and convergence over the Great Plains that is offset by transient eddy divergence. In the winter half year the models project drying for the southwest and wetting to the north. Changes in the mean flow moisture convergence are largely responsible across the west but intensified transient eddy moisture convergence wets the northeast. In the summer half year widespread declines in precipitation minus evaporation (P − E) are supported by mean flow moisture divergence across the west and transient eddy divergence in the Great Plains. The changes in mean flow convergence are related to increases in specific humidity but also depend on changes in the mean flow including increased low-level divergence in the U.S. Southwest and a zonally varying wave that wets the North American west and east coasts in winter and dries the U.S. Southwest. Increased transient eddy fluxes occur even as low-level eddy activity weakens and arise from strengthened humidity gradients. A full explanation of North American hydroclimate changes will require explanation of mean and transient circulation changes and the coupling between the moisture and circulation fields.

North American west coast summer low cloudiness: Broadscale variability associated with sea surface temperature

Six decades of observations at 20 coastal airports, from Alaska to southern California, reveal coherent interannual to interdecadal variation of coastal low cloudiness (CLC) from summer to summer over this broad region. The leading mode of CLC variability represents coherent variation, accounting for nearly 40% of the total CLC variance spanning 1950–2012. This leading mode and the majority of individual airports exhibit decreased low cloudiness from the earlier to the later part of the record. Exploring climatic controls on CLC, we identify North Pacific Sea Surface Temperature anomalies, largely in the form of the Pacific Decadal Oscillation (PDO) as well correlated with, and evidently helping to organize, the coherent patterns of summer coastal cloud variability. Links from the PDO to summer CLC appear a few months in advance of the summer. These associations hold up consistently in interannual and interdecadal frequencies.

Edward Wright’s World Chart of 1599

Corroborating evidence is presented from Edward Wright’s 1599 World Chart to identify Nehalem Bay as the place where Sir Francis Drake’s landed on the North American west coast (Nova Albion) in order to repair his ship during his famous circumnavigation from 1577 to 1580. Evidence from Philip Costaggini’s Civil Engineering Master’s Thesis Survey of Artifacts at Neahkahnie Mountain, Oregon (1982) is also presented. The difficulties in identification are attributed to the confiscation of Drake’s logs and charts by Queen Elizabeth I and to her decree that releasing information about the voyage was punishable by death. Although there are approximately seventeen theorized landing sites, the case for Nehalem Bay is strong.

Non-random biodiversity loss underlies predictable increases in viral disease prevalence

Disease dilution (reduced disease prevalence with increasing biodiversity) has been described for many different pathogens. Although the mechanisms causing this phenomenon remain unclear, the disassembly of communities to predictable subsets of species, which can be caused by changing climate, land use or invasive species, underlies one important hypothesis. In this case, infection prevalence could reflect the competence of the remaining hosts. To test this hypothesis, we measured local host species abundance and prevalence of four generalist aphid-vectored pathogens (barley and cereal yellow dwarf viruses) in a ubiquitous annual grass host at 10 sites spanning 2000 km along the North American West Coast. In laboratory and field trials, we measured viral infection as well as aphid fecundity and feeding preference on several host species. Virus prevalence increased as local host richness declined. Community disassembly was non-random: ubiquitous hosts dominating species-poor assemblages were among the most competent for vector production and virus transmission. This suggests that non-random biodiversity loss led to increased virus prevalence. Because diversity loss is occurring globally in response to anthropogenic changes, such work can inform medical, agricultural and veterinary disease research by providing insights into the dynamics of pathogens nested within a complex web of environmental forces.

"Quiet Americans in India": The CIA and the Politics of Intelligence in Cold War South Asia

In February 1967, officials from the Central Intelligence Agency (CIA) were horrified when the American west-coast magazine, Ramparts, exposed the U.S. intelligence organization’s longstanding financial relationships with a number of international educational institutions and cultural bodies. In a series of articles, reproduced in The New York Times and The Washington Post, Ramparts documented the CIA’s provision of covert funding to, among others, the National Students Association, Asia Foundation, and Congress for Cultural Freedom (CCF). In India, an outpouring of public indignation ensued when it became clear that the Indian Committee for Cultural Freedom, a local offshoot of the CCF, had accepted money from the CIA. The global spotlight cast upon some of the CIA’s more questionable activities had a profound and enduring impact upon Indian perceptions of the United States’ government and its external intelligence service. In the wake of the Ramparts scandal, the CIA came to occupy a prominent place in Indo–U.S. cultural and political discourse. For the remainder of the twentieth century, and beyond, anti-American elements inside and outside India drew repeatedly upon the specter of CIA subversion as a means of undermining New Delhi’s relationship with Washington.

Predictability Characteristics of Landfalling Cyclones along the North American West Coast

Abstract The predictability of North Pacific cyclones can vary widely, from highly accurate prediction of storm intensity and location to forecast position errors of hundreds of kilometers and central pressure errors of tens of hectopascals. In this study, a Weather Research and Forecasting Model (WRF) ensemble Kalman filter is used to investigate predictability of landfalling cyclones on the west coast of North America over two winter seasons (2008/09 and 2009/10). Predictability is defined as the ensemble spread of cyclone central pressure at the final forecast time (24 h) where large spread means low predictability. Both ensemble spread and ensemble initial-condition sensitivity are examined for a wide variety of cyclones that occurred during the two seasons. Storms that are deepening and track from the southwest exhibit the largest ensemble initial-condition sensitivity and highest ensemble spread compared to decaying storms and storms that track from other directions. Storms that end south of 40°N, typically slow moving storms from the northwest, exhibit higher predictability regardless of whether or not they are deepening or decaying. Cyclones with large ensemble spread and low sensitivity are mature cyclones whose low predictability likely results from large initial-condition spread instead of large perturbation growth. These results highlight particular synoptic situations and cyclone characteristics that are associated with low predictability and can potentially be used to improve forecasts through improved observational coverage.

Niche Conservatism and the Future Potential Range of Epipactis helleborine (Orchidaceae)

The aim of the present study was to evaluate the current distribution of suitable niches for the invasive orchid species, Epipactis helleborine, and to estimate the possibility of its further expansion. Moreover, niche modeling tools were used to explain its rapid expansion in North America and to test the niche conservatism of the species. The maximum entropy method was used to create models of the suitable niche distribution. A database of E. helleborine localities was prepared based on the examination of herbarium specimens, information from electronic databases as well as data gathered during field works. The differences between the niches occupied by native and invasive populations were evaluated using the niche overlap and niche identity test indexes. Moreover, the coverage of the most suitable habitats for the species was measured for three future scenarios as well as for the present time model. Populations of E. helleborine occupy North American west coast habitats very similar to those preferred by native, Eurasian populations, while the expansion in the east coast is related to the niche shift. The created models of suitable niche distribution indicate that the species does not realize its potential niche in the native range. The total surface of the habitats potentially available for E. helleborine will decrease in all climate change scenarios created for 2080.

New Cosmopolitanisms of Forgotten Diasporas

New Cosmopolitanisms of Forgotten Diasporas J. Daniel Elam (bio) Bengali Harlem and the Lost Histories of South Asian America. By Vivek Bald. Cambridge, MA: Harvard University Press, 2013. 320 pages. $35.00 (cloth). Stranger Intimacy: Contesting Race, Sexuality, and the Law in the North American West. By Nayan Shah. Berkeley: University of California Press, 2012. 358 pages. $65.00 (cloth). $27.95 (paper). Colored Cosmopolitanism: The Shared Struggle for Freedom in the United States and India. By Nico Slate. Cambridge, MA: Harvard University Press, 2012. 344 pages. $39.95 (cloth). In a Georgia courtroom in 1909, Calcutta-born Abba Dolla pulled up his sleeve to show the underside of his forearm to the judge. Although the judge noted that Dolla was "dark," the skin on his forearms "was sufficiently transparent for the blue color of the veins to show very clearly." This allowed Dolla to prove "Caucasian" status and, consequently, gain US citizenship. Dolla had purchased a lot in a "whites only" cemetery, which strengthened his application for citizenship. But Dolla lived in a black neighborhood in Savannah and had suggested two black friends as character witnesses. Dolla's ability to navigate the arbitrary racial politics of the US court system runs parallel to his ability to navigate networks of support in Savannah's black neighborhoods as well as global networks of trade that stretched from Georgia to Bengal. Like Dolla, South Asian laborers and thinkers in the United States at the turn of the twentieth century left few traces of their lives, but they participated quite centrally in networks that stretched across the United States and the world. Three notable recent books chart this early diaspora: Vivek Bald's Bengali Harlem, Nayan Shah's Stranger Intimacy, and Nico Slate's Colored Cosmopolitanism. Bald focuses on Bengali Muslims in black neighborhoods in New York, New Orleans, and Detroit; Shah tracks the relationships that develop between [End Page 425] Punjabi migrant labor, poor white labor, and indigenous labor forces on the North American west coast; and Slate illuminates a shared struggle between black American and Indian anticolonial thinkers across the twentieth century. Though the three writers approach the period via different archival materials, all three reveal a history of a shared and global struggle against racial, imperial, sexual, and class injustice. These new histories of early South Asian migration and circulation give a thick description of itinerant lives in the United States in the early decades of the twentieth century. On three different scales—from the intimate to the global—these histories trace communities' attempts to support one another beyond or underneath the American and British Empires, and sketch alternative ethical and political projects enacted by those who have been neglected by the nation. The three texts under consideration advance the transnational turn that Janice Radway, in her presidential address at the 1998 American Studies Association meeting,1 noted as the most significant development in the field's recent history. These works join, on the one hand, the critiques of national homogeneity made under the rubrics of identity politics and, on the other, the critiques of US homogeneity highlighted by the nation's twentieth-century imperial practices. Such critiques make it difficult, Radway argued, to imagine a field of American studies that was loyal to any single imagined community. The figures under analysis in Slate, Shah, and Bald were active members in multiple affective communities, some of which stretch around the globe and some of which are within arm's reach. If these three texts challenge our assumptions about the homogeneity of migrant identity and neighborhoods of color, they should also challenge our assumptions about the conformity of experiences of transnationalism. Refuting simple celebrations of transnationalism (as well as daft critiques of globalization), these books focus instead on the discordant and inconsonant effects of global migration, dialogue, and travel. Transnationalism's twentieth-century history emerges as a complicated relationship of people not across states but within the fissures of borders. Slate's Colored Cosmopolitanism constructs a long history of activism beneath the color line, and catalogs the black Americans writing about, corresponding with, and acting with Indians from the turn of the century to the 1960s. "Colored cosmopolitanism," in Slate's...

Lignocellulosic ethanol production from woody biomass: The impact of facility siting on competitiveness

Abstract Just as temperate region pulp and paper companies need to compete with Brazilian eucalyptus pulp producers, lignocellulosic biofuel producers in North America and Europe, in the absence of protectionist trade policies, will need to be competitive with tropical and sub-tropical biofuel producers. This work sought to determine the impact of lignocellulosic ethanol biorefinery siting on economic performance and minimum ethanol selling price (MESP) for both east and west coast North American fuel markets. Facility sites included the pine-dominated Pacific Northwest Interior, the mixed deciduous forest of Ontario and New York, and the Brazilian state of Espirito Santo. Feedstock scenarios included both plantation (poplar, willow, and eucalyptus, respectively) and managed forest harvest. Site specific variables in the techno-economic model included delivered feedstock cost, ethanol delivery cost, cost of capital, construction cost, labour cost, electricity revenues (and co-product credits), and taxes, insurance, and permits. Despite the long shipping distance from Brazil to North American east and west coast markets, the MESP for Brazilian-produced eucalyptus lignocellulosic ethanol, modelled at $0.74 L−1, was notably lower than that of all North American-produced cases at $0.83–1.02 L−1.