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The U.S. Southwest is projected to experience increasing aridity due to climate change. We quantify the resulting impacts on ambient dust levels and public health using methods consistent with the Environmental Protection Agency's Climate Change Impacts and Risk Analysis framework. We first demonstrate that U.S. Southwest fine (PM2.5) and coarse (PM2.5‐10) dust levels are strongly sensitive to variability in the 2‐month Standardized Precipitation‐Evapotranspiration Index across southwestern North America. We then estimate potential changes in dust levels through 2099 by applying the observed sensitivities to downscaled meteorological output projected by six climate models following an intermediate (Representative Concentration Pathway 4.5, RCP4.5) and a high (RCP8.5) greenhouse gas concentration scenario. By 2080–2099 under RCP8.5 relative to 1986–2005 in the U.S. Southwest: (1) Fine dust levels could increase by 57%, and fine dust‐attributable all‐cause mortality and hospitalizations could increase by 230% and 360%, respectively; (2) coarse dust levels could increase by 38%, and coarse dust‐attributable cardiovascular mortality and asthma emergency department visits could increase by 210% and 88%, respectively; (3) climate‐driven changes in dust concentrations can account for 34–47% of these health impacts, with the rest due to increases in population and baseline incidence rates; and (4) economic damages of the health impacts could total $47 billion per year additional to the 1986–2005 value of $13 billion per year. Compared to national‐scale climate impacts projected for other U.S. sectors using the Climate Change Impacts and Risk Analysis framework, dust‐related mortality ranks fourth behind extreme temperature‐related mortality, labor productivity decline, and coastal property loss. Plain Language Summary: The southwestern United States is projected to experience severe, multidecadal droughts due to human‐caused climate change. Mineral dust particles are a major contributor to air pollution in this region due to abundant deserts and drylands. To what extent could airborne dust levels increase as a result of the projected drought conditions? To answer this question, we first investigate the influence of drought conditions across southwestern North America on dust activity in recent years. We then use the observed relationships between dust and droughts to estimate future changes in dust levels—and the associated excess deaths and illnesses—through the end of the century, using projections of temperature and precipitation from global climate models following two plausible (high and intermediate) greenhouse gas emissions scenarios. Under the high emissions scenario, premature mortality associated with dust exposure increases by 220% and hospitalization increases by 160% toward the end of this century, due to combined increases in population, disease rates, and dust levels. The annual economic damages of these health impacts are estimated to be $47 billion per year additional to the present‐day value of $13 billion per year, making climate‐driven changes in dust concentrations one of the costliest impacts projected for the United States so far. Key Points: Increasing aridity may cause dust levels in the U.S. Southwest to rise by 40% in 2090 under a high greenhouse gas concentration scenarioDust‐related mortality could increase by 220% in 2090 under the high scenarioEstimated economic damages from dust‐related mortality make this one of the costliest climate impacts projected for the United States so far [ABSTRACT FROM AUTHOR]

Pollen is an important environmental cause of allergic asthma episodes. Prior work has established a proof of concept for assessing projected climate change impacts on future oak pollen exposure and associated health impacts. This paper uses additional monitor data and epidemiologic functions to extend prior analyses, reporting new estimates of the current and projected future health burden of oak, birch, and grass pollen across the contiguous United States. Our results suggest that tree pollen in the spring currently accounts for between 25,000 and 50,000 pollen‐related asthma emergency department (ED) visits annually (95% confidence interval: 14,000 to 100,000), roughly two thirds of which occur among people under age 18. Grass pollen in the summer season currently accounts for less than 10,000 cases annually (95% confidence interval: 4,000 to 16,000). Compared to a baseline with 21st century population growth but constant pollen, future temperature and precipitation show an increase in ED visits of 14% in 2090 for a higher greenhouse gas emissions scenario, but only 8% for a moderate emissions scenario, reflecting projected increases in pollen season length. Grass pollen, which is more sensitive to changes in climatic conditions, is a primary contributor to future ED visits, with the largest effects in the Northeast, Midwest, and Southern Great Plains regions. More complete assessment of the current and future health burden of pollen is limited by the availability of data on pollen types (e.g., ragweed), other health effects (e.g., other respiratory disease), and economic consequences (e.g., medication costs). Key Points: We link pollen, climate, and epidemiological data to estimate the health burden of oak, birch, and grass pollen across the contiguous United StatesWe found that 35,000 to 60,000 asthma emergency department visits (two thirds of these among children) may be linked with pollen each yearWe project that future climate changes could increase pollen‐related asthma emergency department visits by 14% in 2090 [ABSTRACT FROM AUTHOR]

Climate change will have potentially significant effects on freshwater quality due to increases in river and lake temperatures, changes in the magnitude and seasonality of river runoff, and more frequent and severe extreme events. These physical impacts will in turn have economic consequences through effects on riparian development, river and reservoir recreation, water treatment, harmful aquatic blooms, and a range of other sectors. In this paper, we analyze the physical and economic effects of changes in freshwater quality across the contiguous U.S. in futures with and without global-scale greenhouse gas mitigation. Using a water allocation and quality model of 2119 river basins, we estimate the impacts of various projected emissions outcomes on several key water quality indicators, and monetize these impacts with a water quality index approach. Under mitigation, we find that water temperatures decrease considerably and that dissolved oxygen levels rise in response. We find that the annual economic impacts on water quality of a high emissions scenario rise from $1.4 billion in 2050 to $4 billion in 2100, leading to present value mitigation benefits, discounted at 3%, of approximately $17.5 billion over the 2015-2100 period. [ABSTRACT FROM AUTHOR]