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Atmospheric carbon dioxide (C[O.sub.2]) hit a milestone in 2015, when global average concentrations reached 400 ppm for the first time in recorded history. (1) By 2100, the global average could [...]

Abstract. Understanding the effect of temperature on ecologically important species has become a major challenge in the context of global warming. However, the consequences of climate change cannot be accurately [...]

Introduction The demand for plausible future estimates and patterns of disease risks under global environmental change is widespread given that they are a useful aid in setting priorities for health [...], Background: Debates over whether climate change could lead to the amplification of Lyme disease (LD) risk in the future have received much attention. Although recent large-scale disease mapping studies project an overall increase in Lyme disease risk as the climate warms, such conclusions are based on climate-driven models in which other drivers of change, such as land-use/cover and host population distribution, are less considered. Objectives: The main objectives were to project the likely future ecological risk patterns of LD in Europe under different assumptions about future socioeconomic and climate conditions and to explore similarity and uncertainty in the projected risks. Methods: An integrative, spatially explicit modeling study of the ecological risk patterns of LD in Europe was conducted by applying recent advances in process-based modeling of tick-borne diseases, species distribution mapping, and scenarios of land-use/cover change. We drove the model with stakeholder-driven, integrated scenarios of plausible future socioeconomic and climate change [the Shared Socioeconomic Pathway (SSPs) combined with the Representative Concentration Pathways (RCPs)]. Results: The model projections suggest that future temperature increases may not always amplify LD risk: Low emissions scenarios (RCP2.6) combined with a sustainability socioeconomic scenario (SSP1) resulted in reduced LD risk. The greatest increase in risk was projected under intermediate (RCP4.5) rather than high-end (RCP8.5) climate change scenarios. Climate and land-use change were projected to have different roles in shaping the future regional dynamics of risk, with climate warming being likely to cause risk expansion in northern Europe and conversion of forest to agriculture being likely to limit risk in southern Europe. Conclusions: Projected regional differences in LD risk resulted from mixed effects of temperature, land use, and host distributions, suggesting region-specific and cross-sectoral foci for LD risk management policy. The integrated model provides an improved explanatory tool for the system mechanisms of LD pathogen transmission and how pathogen transmission could respond to combined socioeconomic and climate changes. https:// doi.org/10.1289/EHP4615

Author(s): Kathleen A. Alexander 1,2,*, Alexandra K. Heaney 3, Jeffrey Shaman 3 Introduction Across land types, the flow of water (ground water, surface water, and rainfall) has been demonstrated to [...], Background The impacts of climate change on surface water, waterborne disease, and human health remain a growing area of concern, particularly in Africa, where diarrheal disease is one of the most important health threats to children under 5 years of age. Little is known about the role of surface water and annual flood dynamics (flood pulse) on waterborne disease and human health nor about the expected impact of climate change on surface-water-dependent populations. Methods and findings Using the Chobe River in northern Botswana, a flood pulse river-floodplain system, we applied multimodel inference approaches assessing the influence of river height, water quality (bimonthly counts of Escherichia coli and total suspended solids [TSS], 2011-2017), and meteorological variability on weekly diarrheal case reports among children under 5 presenting to health facilities (n = 10 health facilities, January 2007-June 2017). We assessed diarrheal cases by clinical characteristics and season across age groups using monthly outpatient data (January 1998-June 2017). A strong seasonal pattern was identified, with 2 outbreaks occurring regularly in the wet and dry seasons. The timing of outbreaks diverged from that at the level of the country, where surface water is largely absent. Across age groups, the number of diarrheal cases was greater, on average, during the dry season. Demographic and clinical characteristics varied by season, underscoring the importance of environmental drivers. In the wet season, rainfall (8-week lag) had a significant influence on under-5 diarrhea, with a 10-mm increase in rainfall associated with an estimated 6.5% rise in the number of cases. Rainfall, minimum temperature, and river height were predictive of E. coli concentration, and increases in E. coli in the river were positively associated with diarrheal cases. In the dry season, river height (1-week lag) and maximum temperature (1- and 4-week lag) were significantly associated with diarrheal cases. During this period, a 1-meter drop in river height corresponded to an estimated 16.7% and 16.1% increase in reported diarrhea with a 1- and 4-week lag, respectively. In this region, as floodwaters receded from the surrounding floodplains, TSS levels increased and were positively associated with diarrheal cases (0- and 3-week lag). Populations living in this region utilized improved water sources, suggesting that hydrological variability and rapid water quality shifts in surface waters may compromise water treatment processes. Limitations include the potential influence of health beliefs and health seeking behaviors on data obtained through passive surveillance. Conclusions In flood pulse river-floodplain systems, hydrology and water quality dynamics can be highly variable, potentially impacting conventional water treatment facilities and the production of safe drinking water. In Southern Africa, climate change is predicted to intensify hydrological variability and the frequency of extreme weather events, amplifying the public health threat of waterborne disease in surface-water-dependent populations. Water sector development should be prioritized with urgency, incorporating technologies that are robust to local environmental conditions and expected climate-driven impacts. In populations with high HIV burdens, expansion of diarrheal disease surveillance and intervention strategies may also be needed. As annual flood pulse processes are predominantly influenced by climate controls in distant regions, country-level data may be inadequate to refine predictions of climate-health interactions in these systems.

Introduction The effects of increasing temperature, elevated ρ[CO.sub.2], decreased pH, and reduced carbonate saturation on marine systems is a burgeoning field of research as we attempt to understand potential future [...], Shell calcification in argonauts is unique. Only females of these cephalopods construct the paper nautilus shell, which is used as a brood chamber for developing embryos in the pelagic realm. As one of the thinnest (225 gm) known adult mollusc shells, and lacking an outer protective periostracum-like cover, this shell may be susceptible to dissolution as the ocean warms and decreases in pH. Vulnerability of the A. nodosa shell was investigated through immersion of shell fragments in multifactorial experiments of control (19 °C/pH 8.1; ρ[CO.sub.2] 419; [ω.sub.ca] = 4.23) and near-future conditions (24 °C/pH 7.8-7.6; p[C0.sub.2] 932-1525; [ω.sub.ca] = 2.72-1.55) for 14 days. More extreme pH treatments (pH 7.4-7.2; ρ[CO.sub.2] 2454-3882; [ω.sub.ca] = 1.20-0.67) were used to assess tipping points in shell dissolution. X-ray diffractometry revealed no change in mineralogy between untreated and treated shells. Reduced shell weight due to dissolution was evident in shells incubated at pH 7.8 (projected for 2070) after 14 days at control temperature, with increased dissolution in warmer and lower pH treatments. The greatest dissolution was recorded at 24 °C (projected for local waters by 2100) compared to control temperature across all low-pH treatments. Scanning electron microscopy revealed dissolution and etching of shell mineral in experimental treatments. In the absence of compensatory mineralization, the uncovered female brood chamber will be susceptible to dissolution as ocean pH decreases. Since the shell was a crucial adaptation for the evolution of the argonauts' holopelagic existence, persistence of A. nodosa may be compromised by shell dissolution in an ocean-change world.

Introduction The health of coral reefs is declining on a global scale and continues to be threatened by overfishing and habitat destruction. Anthropogenically induced global climate change has been identified [...], Recent research has explored the possibility that increased sea-surface temperatures and decreasing pH (ocean acidification) contribute to the ongoing decline of coral reef ecosystems. Within corals, a diverse microbiome exerts significant influence on biogeochemical and ecological processes, including food webs, organismal life cycles, and chemical and nutrient cycling. Microbes on coral reefs play a critical role in regulating larval recruitment, bacterial colonization, and pathogen abundance under ambient conditions, ultimately governing the overall resilience of coral reef systems. As a result, microbial processes may be involved in reef ecosystem-level responses to climate change. Developments of new molecular technologies, in addition to multidisciplinary collaborative research on coral reefs, have led to the rapid advancement in our understanding of bacterially mediated reef responses to environmental change. Here we review new discoveries regarding (1) the onset of coral-bacterial associations; (2) the functional roles that bacteria play in healthy corals; and (3) how bacteria influence coral reef response to environmental change, leading to a model describing how reef microbiota direct ecosystem-level response to a changing global climate.

Predicting species' responses to climate change is a major challenge in ecology. Plants have been a focus of study because their responses can affect entire food webs, disturbance regimes and [...], Warming experiments are increasingly relied on to estimate plant responses to global climate change (1,2). For experiments to provide meaningful predictions of future responses, they should reflect the empirical record of responses to temperature variability and recent warming, including advances in the timing of flowering and leafing (3-5). We compared phenology (the timing of recurring life history events) in observational studies and warming experiments spanning four continents and 1,634 plant species using a common measure of temperature sensitivity (change in days per degree Celsius). We show that warming experiments underpredict advances in the timing of flowering and leafing by 8.5-fold and 4.0-fold, respectively, compared with long-term observations. For species that were common to both study types, the experimental results did not match the observational data in sign or magnitude. The observational data also showed that species that flower earliest in the spring have the highest temperature sensitivities, but this trend was not reflected in the experimental data. These significant mismatches seem to be unrelated to the study length or to the degree of manipulated warming in experiments. The discrepancy between experiments and observations, however, could arise from complex interactions among multiple drivers in the observational data, or it could arise from remediable artefacts in the experiments that result in lower irradiance and drier soils, thus dampening the phenological responses to manipulated warming. Our results introduce uncertainty into ecosystem models that are informed solely by experiments and suggest that responses to climate change that are predicted using such models should be re-evaluated.

Morpheus extends his open hand to Neo, revealing two pills--one red, one blue. He solemnly states, 'This is your last chance. After this, there is no turning back. You take [...]

Introduction Throughout human evolution, atmospheric carbon dioxide (C[O.sub.2]) levels have been close to 250 ppm (Honisch et al. 2009). Today, greenhouse gas emissions due to human activities are driving global [...], Background: Climate change models predict that atmospheric carbon dioxide [C[O.sub.2]] levels will be between 700 and 900 ppm within the next 80 y. Despite this, the direct physiological effects of exposure to slightly elevated atmospheric C[O.sub.2] (as compared with ~410 ppm experienced today), especially when exposures extend from preconception to adulthood, have not been thoroughly studied. OBJECTIVES: In this study we aimed to assess the respiratory structure and function effects of long-term exposure to 890 ppm C[O.sub.2] from preconception to adulthood using a mouse model. Methods: We exposed mice to C[O.sub.2] (~ 890 ppm) from prepregnancy, through the in utero and early life periods, until 3 months of age, at which point we assessed respiratory function using the forced oscillation technique, and lung structure. RESULTS: C[O.sub.2] exposure resulted in a range of respiratory impairments, particularly in female mice, including higher tissue elastance, longer chord length, and lower lung compliance. Importantly, we also assessed the lung function of the dams that gave birth to our experimental subjects. Even though these mice had been exposed to the same level of increased C[O.sub.2] for a similar amount of time (~ 8 wk), we measured no impairments in lung function. This suggests that the early life period, when lungs are undergoing rapid growth and development, is particularly sensitive to C[O.sub.2]. Discussion: To the best of our knowledge, this study, for the first time, shows that long-term exposure to environmentally relevant levels of C[O.sub.2] can impact respiratory function in the mouse. https://doi.org/10.1289/EHP7305

Author Affiliations: The year 2019 was the second warmest ever reported and closed the warmest decade on record. In 2020, yet again, devastating wildfires have burned millions of acres in [...], Scientists and health professionals must commit to preparing for the health effects of climate change through increased research, education and self-assessment.

The respiratory tract and immune system both take a hard hit during a dust storm. (1) Bits of soil and dirt kicked up by the wind can carry bacteria, fungi, [...]

Introduction Climate change and physical inactivity are both top-priority public health issues. Physical activity, including bicycling, has been linked to lower risks of cardiovascular disease, diabetes, cancer, hypertension, obesity, and [...], Background: Physical activity is one of the best disease prevention strategies, and it is influenced by environmental factors such as temperature. Objectives: We aimed to illuminate the relation between ambient temperature and bikeshare usage and to project how climate change-induced increasing ambient temperatures may influence active transportation in New York City. Methods: The analysis leverages Citi Bike[R] bikeshare data to estimate participation in outdoor bicycling in New York City. Exposure-response functions are estimated for the relation between daily temperature and bike usage from 2013 to 2017. The estimated exposure-response relation is combined with temperature outputs from 21 climate models (run with emissions scenarios RCP4.5 and RCP8.5) to explore how climate change may influence future bike utilization. Results: Estimated daily hours and distance ridden significantly increased as temperatures increased, but then declined at temperatures above 26-28[degrees]C. Bike usage may increase by up to 3.1% by 2070 due to climate change. Future ridership increases during the winter, spring, and fall may more than offset future declines in summer ridership. Discussion: Evidence suggesting nonlinear impacts of rising temperatures on health-promoting bicycle ridership demonstrates how challenging it is to anticipate the health consequences of climate change. We project increases in bicycling by mid-century in NYC, but this trend may reverse as temperatures continue to rise further into the future. https://doi.org/10.1289/EHP4039

Will climate change increase the likelihood of wildfires and inland flooding across the United States? If so, how many people might be affected? Those are the questions posed by a [...]

Introduction Sub-Saharan Africa (SSA) has contributed the least of any world region to the global accumulation of greenhouse gas emissions; however, this region will probably be more vulnerable to the [...]

Projected changes in climate are expected to play a complicated role in global crop production. Rising levels of atmospheric carbon dioxide (C[O.sub.2]) may improve yield, but higher average temperatures and [...]

The bacterium that causes the plague, which killed millions of Europeans over four centuries from the 1350s, was repeatedly reintroduced from Asia and did not establish itself in European rodents [...]