Bleaching susceptibility and mortality of corals are determined by fine-scale differences in symbiont type

Coral bleaching has been identified as one of the major contributors to coral reef decline, and the occurrence of different symbionts determined by broad genetic groupings (clades A–H) is commonly used to explain thermal responses of reef-building corals. By using Stylophora pistillata as a model, we monitored individual tagged colonies in situ over a two-year period and show that fine level genetic variability within clade C is correlated to differences in bleaching susceptibility. Based on denaturing gradient gel electrophoresis of the internal transcribed spacer region 2, visual bleaching assessments, symbiont densities, host protein, and pulse amplitude modulated fluorometry, we show that subcladal types C78 and C8/a are more thermally tolerant than C79 and C35/a, which suffered significant bleaching and postbleaching mortality. Although additional symbiont types were detected during bleaching in colonies harboring types C79 and C35/a, all colonies reverted back to their original symbionts postbleaching. Most importantly, the data propose that the differential mortality of hosts harboring thermally sensitive versus resistant symbionts rather than symbiont shuffling/switching within a single host is responsible for the observed symbiont composition changes of coral communities after bleaching. This study therefore highlights that the use of broad cladal designations may not be suitable to describe differences in bleaching susceptibility, and that differential mortality results in a loss of both symbiont and host genetic diversity and therefore represents an important mechanism in explaining how coral reef communities may respond to changing conditions.     

From the Cover: Near-linear cost increase to reduce climate-change risk

One approach in climate-change policy is to set normative long-term targets first and then infer the implied emissions pathways. An important example of a normative target is to limit the global-mean temperature change to a certain maximum. In general, reported cost estimates for limiting global warming often rise rapidly, even exponentially, as the scale of emission reductions from a reference level increases. This rapid rise may suggest that more ambitious policies may be prohibitively expensive. Here, we propose a probabilistic perspective, focused on the relationship between mitigation costs and the likelihood of achieving a climate target. We investigate the qualitative, functional relationship between the likelihood of achieving a normative target and the costs of climate-change mitigation. In contrast to the example of exponentially rising costs for lowering concentration levels, we show that the mitigation costs rise proportionally to the likelihood of meeting a temperature target, across a range of concentration levels. In economic terms investing in climate mitigation to increase the probability of achieving climate targets yields “constant returns to scale,” because of a counterbalancing rapid rise in the probabilities of meeting a temperature target as concentration is lowered.     

国境口岸加强对裂谷热早期预警的措施探讨

目的 裂谷热是由蚊子传播的,以急性、高热为特征的病毒性人畜共患病,OIE将其列为A类传染病.目前我国尚未有感染裂谷热的报道,但是该病的全球扩散形势依然严峻.方法 对建立安全高效的动物卫生监测体系和裂谷热气候模型两种预警措施进行简单的综述.结果 裂谷热在动物发病情况优先于人体发病,因此建立动物卫生监测系统早期预警机制效果显著,同时利用裂谷热媒介生物条件特异性可以通过卫星遥感技术建立气候模型进行早期预警.结论 国境口岸加强对裂谷热的早期预警能够及时地监测疫病的发展趋势,对有关部门采取相应措施来防止疫病的入侵具有十分重要的意义.     

疾病预防控制档案的长期趋势及影响因素分析

目的通过对绵阳疾控中心有史以来的全部归档文件从数量上的动态变动趋势及其影响因素的分析,预测今后一段时期疾控档案数量可能达到的规模,为疾控档案管理提供措施。方法应用动态数列理论对档案资料作动态变动趋势描述并作出预测;查阅相关历史文献、大众媒体公开资料探讨影响疾控档案动态走势因素。结果疾控档案在数量上随着时间的延续整体呈波浪上升态势,其定基发展速度为18.99倍,平均发展速度为1.25倍,平均增长速度是0.25倍,预计未来一段时间的2012-2014年归档文件数量平均每年将达到765.66件、2015-2017年将达956.96件;影响疾控档案归档文件数量动态变动趋势的因素有历史原因和档案本身原因。结论疾控档案资料的动态走势与疾控工作的工作量、档案工作的工作量呈正比,工作量越大存档文件越多;适时清理过期档案文件、档案资料在整理时准确归类是缓解储存空间压力的必要手段。     

Deoxygenation of the Baltic Sea during the last century

Deoxygenation is a global problem in coastal and open regions of the ocean, and has led to expanding areas of oxygen minimum zones and coastal hypoxia. The recent expansion of hypoxia in coastal ecosystems has been primarily attributed to global warming and enhanced nutrient input from land and atmosphere. The largest anthropogenically induced hypoxic area in the world is the Baltic Sea, where the relative importance of physical forcing versus eutrophication is still debated. We have analyzed water column oxygen and salinity profiles to reconstruct oxygen and stratification conditions over the last 115 y and compare the influence of both climate and anthropogenic forcing on hypoxia. We report a 10-fold increase of hypoxia in the Baltic Sea and show that this is primarily linked to increased inputs of nutrients from land, although increased respiration from higher temperatures during the last two decades has contributed to worsening oxygen conditions. Although shifts in climate and physical circulation are important factors modulating the extent of hypoxia, further nutrient reductions in the Baltic Sea will be necessary to reduce the ecosystems impacts of deoxygenation.Dead zones are hypoxic (low-oxygen) areas unable to support most marine life, and over the past 50 y they have spread rapidly in the open ocean (1) as well as in coastal ecosystems (2). Global warming is thought to be a major driver for these changes (3), although biogeochemical factors have also been recognized, especially in coastal marine ecosystems (4, 5). In the Baltic Sea, the present spread of hypoxia is the combined result of climate changes influencing deepwater oxygenation (6) and increased eutrophication (7, 8), resulting in a hypoxic area ranging between 12,000 and 70,000 km² with an average of 49,000 km² over the time period 1961–2000 (7). Here, we separate the effects of the two factors on oxygen conditions.Physical factors are an important consideration in whether an ecosystem will experience hypoxia. The Baltic Sea is naturally prone to hypoxia due to a restricted water exchange with the ocean and a long residence time above 30 y (9, 10). Saltier, denser water from the North Atlantic flows over a series of shallow sills in the Danish Straits to ventilate waters below the permanent halocline and are governed by meteorological-induced variations in sea levels (11), displaying variations at decadal scales (12, 13). The dense saltwater inflows bring new supplies of oxygen to bottom waters, but at the same time enhance stratification, creating larger bottom areas that experience hypoxia (14). In particular, the ventilation of the deeper waters is attributed to events of larger inflows of high-saline water (>17), termed Major Baltic Inflows (MBIs), that have been less frequent in the last three decades (6).Climate warming decreases oxygen solubility due to higher water temperature, increases stratification, and enhances respiration processes (15). Climate warming is likely to be accompanied by increased precipitation and inflows of freshwater and nutrients to coastal waters in many areas of the globe. Increasing nutrient inputs from land stimulates primary production and export of organic material to the deep waters, thereby disrupting the subtle natural balance between oxygen supply from physical processes and oxygen demand from consumption of organic material. However, the importance of decreasing oxygenation versus increasing nutrient inputs for explaining the recent spread of hypoxia is not known (6, 7).Water column measurements of dissolved oxygen concentrations began around 1900 with more regularly spaced measurements commencing in the 1960s (Fig. S1), allowing a more consistent assessment of the spatial extent of hypoxia (7, 14). The sparse temporal and spatial resolution of oxygen data before 1960 allowed only assessing hypoxia at specific locations (16) or specific years (17). To our knowledge, our study is the first to report basin-wide trends of stratification and oxygen conditions from 1898 to present, and here we will focus on the two basins that have perennial hypoxia—the Bornholm Basin and the Gotland Basin (Fig. S2). These two basins are connected via a channel with a sill depth of 60 m.     

Exposure to ambient black carbon derived from a unique inventory and high-resolution model

Black carbon (BC) is increasingly recognized as a significant air pollutant with harmful effects on human health, either in its own right or as a carrier of other chemicals. The adverse impact is of particular concern in those developing regions with high emissions and a growing population density. The results of recent studies indicate that BC emissions could be underestimated by a factor of 2–3 and this is particularly true for the hot-spot Asian region. Here we present a unique inventory at 10-km resolution based on a recently published global fuel consumption data product and updated emission factor measurements. The unique inventory is coupled to an Asia-nested (∼50 km) atmospheric model and used to calculate the global population exposure to BC with fully quantified uncertainty. Evaluating the modeled surface BC concentrations against observations reveals great improvement. The bias is reduced from −88% to −35% in Asia when the unique inventory and higher-resolution model replace a previous inventory combined with a coarse-resolution model. The bias can be further reduced to −12% by downscaling to 10 km using emission as a proxy. Our estimated global population-weighted BC exposure concentration constrained by observations is 2.14 μg⋅m⁻³; 130% higher than that obtained using less detailed inventories and low-resolution models.Black carbon (BC), or soot, emitted from incomplete combustion of carbonaceous fuels is an air pollutant which also plays an important role in climate change (1). BC is an indicator of air particulate pollution and BC in ambient air has an impact on human health (2). In a recent study in China, it was found that the effects of BC on morbidity appear to be more robust than the effects of fine particles in general (3, 4).However, global atmospheric aerosol models often underestimate the concentration of BC at the surface, particularly over Asia, by a factor that typically ranges from 2 to 10 (5–7). In one study, the observed BC surface concentration for China could only be reproduced by doubling the emissions prescribed to a transport model (8). It is often argued that the underestimation is due to a low bias in BC emission inventories, suggesting a need to revisit these previous inventories (9).In a bottom-up approach, BC emission is estimated based on the amount of fuel consumed and an emission factor (EF_BC, defined as the amount of BC emitted per unit mass of fuel consumed) for each of various combustion sources. For previous inventories, the lack of EF_BC measurements in developing countries led to high uncertainty in estimating the total emissions (10). In addition, the use of fuel data at the national level is likely to distort the geographical distribution of emissions within large countries such as China and India (11). Recently, a 0.1° × 0.1° fuel database with 64 types of combustion has been developed based on local or national fuel consumption statistics. This database improves the resolution of the spatial distribution of emissions for large countries (12). To fill the data gap in developing countries, a set of EF_BC values has been compiled for various residential solid fuel combustion devices and vehicles (13–20). In addition to the problems with the emission inventories, the coarse resolution of existing global aerosol models also hinders our ability to capture detailed spatial variation, leading to poor agreement between model prediction and observations (7).In this study we develop and evaluate a unique global BC emission inventory using a zoomed aerosol model, and estimate the global population’s exposure to BC with a focus on Asia. The influence of model resolution and the use of an updated emission inventory on the calculated BC concentration are evaluated against field observations.     

Nonlinear permanent migration response to climatic variations but minimal response to disasters

We present a microlevel study to simultaneously investigate the effects of variations in temperature and precipitation along with sudden natural disasters to infer their relative influence on migration that is likely permanent. The study is made possible by the availability of household panel data from Indonesia with an exceptional tracking rate combined with frequent occurrence of natural disasters and significant climatic variations, thus providing a quasi-experiment to examine the influence of environment on migration. Using data on 7,185 households followed over 15 y, we analyze whole-household, province-to-province migration, which allows us to understand the effects of environmental factors on permanent moves that may differ from temporary migration. The results suggest that permanent migration is influenced by climatic variations, whereas episodic disasters tend to have much smaller or no impact on such migration. In particular, temperature has a nonlinear effect on migration such that above 25 °C, a rise in temperature is related to an increase in outmigration, potentially through its impact on economic conditions. We use these results to estimate the impact of projected temperature increases on future permanent migration. Though precipitation also has a similar nonlinear effect on migration, the effect is smaller than that of temperature, underscoring the importance of using an expanded set of climatic factors as predictors of migration. These findings on the minimal influence of natural disasters and precipitation on permanent moves supplement previous findings on the significant role of these variables in promoting temporary migration.Human migration has been identified as a potentially important response to climate change. Where climate change makes habitation in certain places less desirable or even impossible, people may respond by moving elsewhere. However, the idea that environmental change induces people to migrate remains a widely contested topic, especially given recent findings suggesting that environmental changes may also constrain movement (1–3). Historically, there has been a paucity of empirical demonstrations of environmental effects on population mobility, partly due to sparse data and partly because migration studies have tended to focus on further exploration of social and economic predictors of migration that have already been established as primary drivers. More recently however, new empirical approaches to exploring the relationship between migration and climate change have emerged.Based on a review of the existing literature (SI Text, Literature Review), there is conflicting evidence on the effects of climatic variations and natural disasters on migration, partly arising from the inability to distinguish permanent moves from temporary ones, especially in the case of macrolevel studies that analyze aggregate flows of people. Furthermore, the effects may vary significantly by distance of migration destination, which may also confound the overall effect of environmental factors on migration. Above all, most studies at the microlevel do not simultaneously examine the effects of both disasters and climatic changes on migration, and often use only one aspect of climate, generally variation in rainfall. However, precipitation and temperature are historically correlated and to infer an unbiased effect of either one on migration probability, both need to be included in the model (4).The current study therefore attempts to improve on the existing studies. This study is, to our knowledge, the first at a microlevel to simultaneously explore the effects of sudden natural disasters and climatic variations on permanent migration of the whole household. (Household migration can take several forms: migration of a single member or individual migration; migration of one or more members of the household or split household migration; and migration of whole household, which includes migration of the entire household along with the head of household.) In doing so, we test the effect of temperature along with precipitation on migration decision. We include a summary that allows a quick comparison of the methodology used in our study compared with previous studies in terms of the choice of environmental variables to predict migration (Table S1). Prior studies have primarily examined individual migration behavior, which may capture both temporary and permanent migration. In contrast, province-level migration of entire households, as we show (with the use of data that follows households over a period of 15 y), tends to be more permanent. (We hereafter use the term “permanent.”) To our knowledge, the only other studies that focus on household migration explore the mechanisms by which natural disasters can deter migration of the household or its relatives (5, 6). By studying migration behavior of the whole household, we are able to focus on permanent migration, and therefore directly test how sudden disasters along with variations in rainfall and temperature affect permanent and relatively longer distance (province-to-province) migration as opposed to temporary movement; this allows us to complement the findings in some existing studies that generally conclude that natural disasters and rainfall result in temporary and short-distance moves while providing new evidence on the temperature–migration link in the context of microlevel studies.To achieve these goals, we chose Indonesia as our study site because as the world’s largest archipelago situated in a tectonically active location, the country is highly exposed to both geologic and climatic hazards (SI Text, Background on Indonesia). In addition, as the world’s fourth most populous country with ∼40% of the labor force engaged in agriculture and more than 60% of the total population living in the coastal areas, the country is extremely vulnerable to the impacts of climate variations and extreme events (SI Text, Background on Indonesia). At the same time, the availability of household panel data with an exceptional tracking rate allows us to use a difference-in-differences approach to study the migration of households before and after disasters as well as establish a plausibly causal link between climatic variations and migration. We use the Indonesian Family Life Survey (IFLS), a household panel survey representative of ∼83% of the Indonesian population from 13 of the 27 provinces in 1993 (Fig. S1). The IFLS provides data on 7,185 original households, followed over a period of 15 y (Materials and Methods). The migration outcome we predict captures migration of households, which is likely permanent. We track whole-household migration for a 15-y period during which the original households are followed with a very high retention rate even after they migrate. Some 95% of the migrant households end up migrating only once and do not return to their original province during the entire 15-y period. Therefore, at least in the Indonesian case, the provincial level migration of households seems to be permanent (see SI Text, Internal Migration in Indonesia, for more on internal migration in Indonesia).The household panel data are supplemented with data on natural disasters taken from DesInventar database, which provides disaster-related data using information on disasters of different intensities based on preexisting official data, academic records, newspaper sources, and institutional reports. Different types of disasters may not all affect migration in the same way, thus cancelling out each other’s effects on migration. For our analysis, we therefore separately estimate the effects of each type of disaster. Furthermore, we use multiple measures to capture the different ways in which a disaster may affect the population, for three primary reasons. First, we believe that the intensity of disaster rather than simply the occurrence of disaster should more accurately predict its effect. Measures such as number of deaths, number injured, number of houses destroyed, and amount of financial loss (captured by monetary loss measured in Indonesian Rupiah) from each type of disaster aggregated at the province level are used to capture both the frequency as well as the intensity of disasters. Second, relying on a single measure of a disaster may not capture its overall effect because a certain event may result in large financial losses but inflict little physical harm. Third, using alternate measures of disaster allows one to compare and confirm results, and can be used as a robustness check (Materials and Methods).Finally, for measures of climatic variations, we construct estimates of average temperature and precipitation for each province during each observation interval (Materials and Methods), because temperature and rainfall variations together provide a more complete measure of the extent of climate variations that may affect migration (7).