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Uejio C.K.,University of Wisconsin - Madison | Wilhelmi O.V.,U.S. National Center for Atmospheric Research | Golden J.S.,Duke University | Mills D.M.,Stratus Consulting Inc. | And 2 more authors.
Health and Place | Year: 2011

Extreme heat is an important weather hazard associated with excess mortality and morbidity. We determine the relative importance of heat exposure and the built environment, socioeconomic vulnerability, and neighborhood stability for heat mortality (Philadelphia, PA, USA) or heat distress (Phoenix, AZ, USA), using an ecologic study design. We use spatial Generalized Linear and Mixed Models to account for non-independence (spatial autocorrelation) between neighboring census block groups. Failing to account for spatial autocorrelation can provide misleading statistical results. Phoenix neighborhoods with more heat exposure, Black, Hispanic, linguistically and socially isolated residents, and vacant households made more heat distress calls. Philadelphia heat mortality neighborhoods were more likely to have low housing values and a higher proportion of Black residents. Our methodology can identify important risk factors and geographic areas to target interventions. © 2010 Elsevier Ltd.


Mills D.,Stratus Consulting Inc. | Jones R.,Stratus Consulting Inc. | Carney K.,Stratus Consulting Inc. | St. Juliana A.,Stratus Consulting Inc. | And 6 more authors.
Climatic Change | Year: 2015

This paper develops and applies methods to quantify and monetize projected impacts on terrestrial ecosystem carbon storage and areas burned by wildfires in the contiguous United States under scenarios with and without global greenhouse gas mitigation. The MC1 dynamic global vegetation model is used to develop physical impact projections using three climate models that project a range of future conditions. We also investigate the sensitivity of future climates to different initial conditions of the climate model. Our analysis reveals that mitigation, where global radiative forcing is stabilized at 3.7 W/m2 in 2100, would consistently reduce areas burned from 2001 to 2100 by tens of millions of hectares. Monetized, these impacts are equivalent to potentially avoiding billions of dollars (discounted) in wildfire response costs. Impacts to terrestrial ecosystem carbon storage are less uniform, but changes are on the order of billions of tons over this time period. The equivalent social value of these changes in carbon storage ranges from hundreds of billions to trillions of dollars (discounted). The magnitude of these results highlights their importance when evaluating climate policy options. However, our results also show national outcomes are driven by a few regions and results are not uniform across regions, time periods, or models. Differences in the results based on the modeling approach and across initializing conditions also raise important questions about how variability in projected climates is accounted for, especially when considering impacts where extreme or threshold conditions are important. © 2014, The Author(s).


Overeem I.,University of Colorado at Boulder | Anderson R.S.,University of Colorado at Boulder | Wobus C.W.,Stratus Consulting Inc. | Wobus C.W.,University of Colorado at Boulder | And 3 more authors.
Geophysical Research Letters | Year: 2011

Erosion rates of permafrost coasts along the Beaufort Sea accelerated over the past 50 years synchronously with Arctic-wide declines in sea ice extent, suggesting a causal relationship between the two. A fetch-limited wave model driven by sea ice position and local wind data from northern Alaska indicates that the exposure of permafrost bluffs to seawater increased by a factor of 2.5 during 1979-2009. The duration of the open water season expanded from ∼45 days to ∼95 days. Open water expanded more rapidly toward the fall (∼0.92 day yr -1), when sea surface temperatures are cooler, than into the mid-summer (∼0.71 days yr -1).Time-lapse imagery demonstrates the relatively efficient erosive action of a single storm in August. Sea surface temperatures have already decreased significantly by fall, reducing the potential impact of thermal erosion due to fall season storm waves. Copyright 2011 by the American Geophysical Union.


Barnhart K.R.,University of Colorado at Boulder | Anderson R.S.,University of Colorado at Boulder | Overeem I.,University of Colorado at Boulder | Wobus C.,Stratus Consulting Inc. | And 2 more authors.
Journal of Geophysical Research: Earth Surface | Year: 2014

The Arctic climate is changing, inducing accelerating retreat of ice-rich permafrost coastal bluffs. Along Alaska's Beaufort Sea coast, erosion rates have increased roughly threefold from 6.8 to 19 m yr-1 since 1955 while the sea ice-free season has increased roughly twofold from 45 to 100 days since 1979. We develop a numerical model of bluff retreat to assess the relative roles of the length of sea ice-free season, sea level, water temperature, nearshore wavefield, and permafrost temperature in controlling erosion rates in this setting. The model captures the processes of erosion observed in short-term monitoring experiments along the Beaufort Sea coast, including evolution of melt notches, topple of ice wedge-bounded blocks, and degradation of these blocks. Model results agree with time-lapse imagery of bluff evolution and time series of ocean-based instrumentation. Erosion is highly episodic with 40% of erosion is accomplished during less than 5% of the sea ice-free season. Among the formulations of the submarine erosion rate we assessed, we advocate those that employ both water temperature and nearshore wavefield. As high water levels are a prerequisite for erosion, any future changes that increase the frequency with which water levels exceed the base of the bluffs will increase rates of coastal erosion. The certain increases in sea level and potential changes in storminess will both contribute to this effect. As water temperature also influences erosion rates, any further expansion of the sea ice-free season into the midsummer period of greatest insolation is likely to result in an additional increase in coastal retreat rates. Key Points Coastal erosion is episodic and associated with storms that set up water Heat transfer governs the rate of submarine notch incision and coast retreat Sea level and water temperature will impact future coastal erosion the most ©2014. American Geophysical Union. All Rights Reserved.


Kalkstein L.S.,University of Miami | Kalkstein L.S.,Applied Climatologists Inc | Greene S.,University of Oklahoma | Mills D.M.,Stratus Consulting Inc. | Samenow J.,U.S. EPA Office of Atmospheric Programs
Natural Hazards | Year: 2011

This study estimates the excess mortality attributable to excessive heat events (EHEs) for forty major U. S. cities during 1975-1995 and 1975-2004. We calculate these results using the spatial synoptic classification method to identify EHE days. Step-wise regressions are then used to estimate the location-specific mortality algorithms that can account for the impact of the EHEs' duration, severity, and timing. Our excess mortality results are expressed both as lives lost and associated mortality rates (excess deaths per 100,000 residents) using 2000 Census population estimates. Our results generally show a reduction in EHE-attributable mortality rates since 1996. Adjusting our results to account for changes in the average number of EHE days per year in each period does not affect this general conclusion. However, this adjustment has a considerable impact on a measure of the cities' relative performance in terms of reducing this EHE-attributable excess mortality. Our results indicate there is promise for further reductions in EHE-attributable mortality from the approximately 1300 excess deaths per summer we identify using data from the 1975-2004 period. However, the magnitude of this result highlights the significant health burden of EHEs relative to other extreme weather events in the United States and suggests it is worthy of additional attention. Our results also raise important questions with respect to evaluating the performance of EHE notification and response programs and how EHE-attributable mortality should be estimated for future scenarios, notably for climate change projections. © 2010 Springer Science+Business Media B.V.


Greene S.,University of Oklahoma | Kalkstein L.S.,University of Miami | Kalkstein L.S.,Applied Climatologists Inc. | Mills D.M.,Stratus Consulting Inc. | Samenow J.,U.S. EPA Office of Atmospheric Programs
Weather, Climate, and Society | Year: 2011

This study examines the impact of a changing climate on heat-related mortality in 40 large cities in the United States. A synoptic climatological procedure, the spatial synoptic classification, is used to evaluate present climate-mortality relationships and project how potential climate changes might affect these values. Specifically, the synoptic classification is combined with downscaled future climate projections for the decadal periods of 2020-29, 2045-55, and 2090-99 from a coupled atmospheric-oceanic general circulation model. The results show an increase in excessive heat event (EHE) days and increased heat-attributable mortality across the study cities with the most pronounced increases projected to occur in the Southeast and Northeast. This increase becomes more dramatic toward the end of the twenty-first century as the anticipated impact of climate change intensifies. The health impact associated with different emissions scenarios is also examined. These results suggest that a "business as usual" approach to greenhouse gas emissions mitigation could result in twice as many heat-related deaths by the end of the century than a lower emissions scenario. Finally, a comparison of future estimates of heat-related mortality during EHEs is presented using algorithms developed during two different, although overlapping, time periods, one that includes some recent large-scale significant EHE intervention strategies (1975-2004), and one without (1975-95). The results suggest these public health responses can significantly decrease heat-related mortality. © 2011 American Meteorological Society.


Buddemeier R.W.,Kansas Geological Survey | Lane D.R.,Stratus Consulting Inc. | Martinich J.A.,U.S. Environmental Protection Agency
Climatic Change | Year: 2011

Climatic change threatens the future of coral reefs in the Caribbean and the important ecosystem services they provide. We used a simulation model [Combo ("COral Mortality and Bleaching Output")] to estimate future coral cover in the part of the eastern Caribbean impacted by a massive coral bleaching event in 2005. Combo calculates impacts of future climate change on coral reefs by combining impacts from long-term changes in average sea surface temperature (SST) and ocean acidification with impacts from episodic high temperature mortality (bleaching) events. We used mortality and heat dose data from the 2005 bleaching event to select historic temperature datasets, to use as a baseline for running Combo under different future climate scenarios and sets of assumptions. Results suggest a bleak future for coral reefs in the eastern Caribbean. For three different emissions scenarios from the Intergovernmental Panel on Climate Change (IPCC; B1, A1B, and A1FI), coral cover on most Caribbean reefs is projected to drop below 5% by the year 2035, if future mortality rates are equivalent to some of those observed in the 2005 event (50%). For a scenario where corals gain an additional 1-1. 5°C of heat tolerance through a shift in the algae that live in the coral tissue, coral cover above 5% is prolonged until 2065. Additional impacts such as storms or anthropogenic damage could result in declines in coral cover even faster than those projected here. These results suggest the need to identify and preserve the locations that are likely to have a higher resiliency to bleaching to save as many remnant populations of corals as possible in the face of projected wide-spread coral loss. © 2011 The Author(s).


Hancock G.S.,College of William and Mary | Small E.E.,University of Colorado at Boulder | Wobus C.,Stratus Consulting Incorporated | Wobus C.,University of Colorado at Boulder
Journal of Geophysical Research: Earth Surface | Year: 2011

Field and modeling studies suggest that bedrock channels equilibrate to base-level change through geometry and slope adjustment to imposed discharge, sediment supply, and substrate erodibility conditions. In this study we model the influence of bedrock weathering on channel geometry and slope as mean peak discharge (Qm) and uplift rate (U) vary. We find that channels in which weathering is allowed to increase erodibility are wider, deeper, and less steep than nonweathering channels with the same initial conditions. While fixed erodibility channels maintain similar width/depth ratios regardless of Q m or U, the width/depth ratio of weathering channels is sensitive to uplift rate. At low uplift rates, weathering outpaces erosion, and channels obtain similar width/depth ratios but are wider and less steep than fixed erodibility channels with equal initial conditions. At high uplift rates, erosion outpaces weathering and erodibility remains near the unweathered value, with channel shape and slope nearly identical to a fixed erodibility channel with equal initial conditions. Weathering channels differ most from fixed erodibility channels at intermediate uplift rates, with greater width/depth ratios and lower slopes than fixed erodibility channels with the same initial conditions. Our results support the hypothesis that cross-channel variations in erodibility created by weathering may be an important control on channel geometry and provide guidance for further testing of this hypothesis in natural systems. Copyright 2011 by the American Geophysical Union.


English E.,Stratus Consulting Inc.
American Journal of Agricultural Economics | Year: 2010

Models of recreation behavior have typically ignored the role of fixed annual fees, such as the fee for a recreational license, in determining choice and welfare. We demonstrate how techniques from the literature on discrete-continuous choice and two-part tariffs can address a situation where fixed annual fees are essential to determining the choice of a recreation site. We explore how accounting for value captured by fixed fees can influence the way resource changes are assessed. © The Author (2010). Published by Oxford University Press on behalf of the Agricultural and Applied Economics Association. All rights reserved.


Wobus C.W.,Stratus Consulting Inc. | Wobus C.W.,University of Colorado at Boulder | Tucker G.E.,University of Colorado at Boulder | Anderson R.S.,University of Colorado at Boulder
Journal of Geophysical Research: Earth Surface | Year: 2010

Incised fluvial systems are typically interpreted as recording geologically recent changes in either climate or tectonics. However, few diagnostic tools exist to evaluate whether particular incised landscapes primarily reflect climatic or tectonic perturbation. Here we summarize the results of a simple fluvial sediment transport model that allows us to contrast patterns of fluvial incision driven by changes in hydrology and sediment flux ("climate") with those driven by changes in rock uplift patterns relative to sea level ("tectonics"). Our modeling suggests that there may be diagnostic differences between the spatial and temporal patterns of incision caused by these different processes. In particular, incision driven by climate change is most commonly accompanied by downstream migrating waves of incision and decreases in channel gradient, while under most circumstances incision driven by tectonics will be accompanied by upstream migrating incision and increases in channel gradient. We apply our modeling to a case study of the North American High Plains, where regionally elevated surfaces east of the Rockies have been incised up to 500 m by the fluvial systems draining the core of the range. Although this incision has been interpreted as reflecting a tectonic rejuvenation of the High Plains, our analysis suggests that climate change is at least as plausible an explanation to explain the incision of this landscape. Diagnostic differences between the climate and tectonic end-member scenarios might be obtained via detailed study of the spatial and temporal patterns of terrace abandonment, providing a potentially fruitful target for field investigation. Copyright 2010 by the American Geophysical Union.

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