We describe here changes in stratospheric dynamics and chemistry in a first century‐long sulfate aerosol geoengineering simulation in which the mean surface temperature and the interhemispheric and ...equator‐to‐pole surface temperature gradients were kept near their 2020 levels despite the RCP8.5 emission scenario. Simulations were carried out with the Community Earth System Model, version 1 with the Whole Atmosphere Community Climate Model as its atmospheric component CESM1(WACCM) coupled to a feedback algorithm controlling the magnitude of sulfur dioxide (SO2) injections at four injection latitudes. We find that, throughout the entire geoengineering simulation, the lower stratospheric temperatures increase by ∼0.19 K per Tg SO2 injection per year or ∼10 K with ∼40 Tg SO2/year total SO2 injection. These temperature changes are associated with a strengthening of the polar jets in the stratosphere and weakening of the mean zonal wind in the lower stratosphere subtropics and throughout the troposphere, associated with weaker storm track activity. In the geoengineering simulation the quasi‐biennial oscillation of the tropical lower stratospheric winds remains close to the presently observed quasi‐biennial oscillation, even for large amounts of SO2 injection. Water vapor in the stratosphere increases substantially: by 25% with ∼20 Tg SO2/year annual injection and by up to 90% with a ∼40 Tg SO2/year injection. Stratospheric column ozone in the geoengineering simulation is predicted to recover to or supersede preozone hole conditions by the end of the century.
Key Points
Stratospheric dynamics and chemistry are examined in a geoengineering simulation in which three surface temperature goals are met
Stratospheric extratropical winds increase, subtropical jets and storm tracks weaken, frequency of SSWs is reduced, QBO similar to present
Stratospheric water vapor increases, column ozone increases to preozone hole levels by the end of century, ozone hole recovery is delayed
Abstract
Geoengineering with stratospheric sulfate aerosols can, to some extent, be designed to achieve different climate objectives. Here we use the state‐of‐the‐art Community Earth System Model, ...version 1, with the Whole Atmosphere Community Climate Model as its atmospheric component (CESM1(WACCM)), to compare surface climate and stratospheric effects of two geoengineering strategies. In one, SO
2
is injected into the tropical lower stratosphere at the equator to keep global mean temperature nearly constant under an RCP8.5 scenario, as has been commonly simulated in previous studies. In another, the Geoengineering Large Ensemble (GLENS), SO
2
is injected into the lower stratosphere at four different locations (30°N/S and 15°N/S) to keep global mean temperature, the interhemispheric temperature gradient, and the equator‐to‐pole temperature gradient nearly unchanged. Both simulations are effective at offsetting changes in global mean temperature and the interhemispheric temperature gradient that result from increased greenhouse gases, but only GLENS fully offsets changes in the equator‐to‐pole temperature gradient. GLENS results in a more even aerosol distribution, whereas equatorial injection tends to result in an aerosol peak in the tropics. Moreover, GLENS requires less total injection than in the equatorial case due to different spatial distributions of the aerosols. Many other aspects of surface climate changes, including precipitation and sea ice coverage, also show reduced changes in GLENS as compared to equatorial injection. Stratospheric changes, including heating, circulation, and effects on the quasi‐biennial oscillation are greatly reduced in GLENS as compared to equatorial injection.
Key Points
Tropospheric and stratospheric side effects of equatorial solar geoengineering are reduced if nonequatorial injections are applied
Some residual temperature effects from equatorial injection can be offset with multiple injection locations
There are still residuals in surface climate and the stratosphere that cannot be offset with four injection locations
Nearly all air enters the stratosphere through a single layer in the tropics. The tropical tropopause layer (TTL) is a transition region between the troposphere and stratosphere and its roles include ...regulating stratospheric chemistry and surface climate. Multiscale dynamics existing in the TTL range from transient convection to the hemispheric wave-driven circulation and the relative influences of these processes still remain unclear. This study pays special attention to vertical and horizontal mixing which are associated with breaking gravity waves and Rossby waves, respectively. Our study quantifies the roles of these dynamics by taking advantage of the conservative nature of water vapor in the lower stratosphere. Unable to change concentration in the lowermost stratosphere after passing through the cold point, water vapor becomes a tracer for total transport and its signal is known as the tape recorder. This tape recorder is studied using observations, reanalysis data, a chemistry-climate model (CCM), and simple idealized modeling. Modifying past methods, we are able to capture the seasonal cycle of effective transport in the TTL and we introduce seasonally-dependent dynamics to a one-dimensional model and perform a parameter-sweep to test all possible dynamical combinations. Simulating with unrealistic annual mean transports results in bimodality where either vertical advection or vertical mixing dominate. The solutions that depend on amplified vertical advection disappear when seasonally-dependent transports are used. Overall, all datasets show that vertical mixing is as important to TTL transport as vertical advection itself even during boreal winter when advection peaks. The reanalysis and CCM have increased effective transport compared to observations, however, they rely on different dynamics. The reanalysis has amplified vertical mixing while the CCM has amplified vertical advection. This hints at the possible influence of spurious diffusion from data assimilation and its role in amplifying TTL transport.
Inadequate facilities and hygiene at slaughterhouses can result in contamination of meat and occupational hazards to workers. The objectives of this study were to assess current conditions in ...slaughterhouses in western Kenya and the knowledge, and practices of the slaughterhouse workers toward hygiene and sanitation.
Between February and October 2012 all consenting slaughterhouses in the study area were recruited. A standardised questionnaire relating to facilities and practices in the slaughterhouse was administered to the foreperson at each site. A second questionnaire was used to capture individual slaughterhouse workers' knowledge, practices and recent health events.
A total of 738 slaughterhouse workers from 142 slaughterhouses completed questionnaires. Many slaughterhouses had poor infrastructure, 65% (95% CI 63-67%) had a roof, cement floor and walls, 60% (95% CI 57-62%) had a toilet and 20% (95% CI 18-22%) had hand-washing facilities. The meat inspector visited 90% (95% CI 92-95%) of slaughterhouses but antemortem inspection was practiced at only 7% (95% CI 6-8%). Nine percent (95% CI 7-10%) of slaughterhouses slaughtered sick animals. Only half of workers wore personal protective clothing - 53% (95% CI 51-55%) wore protective coats and 49% (95% CI 46-51%) wore rubber boots. Knowledge of zoonotic disease was low with only 31% (95% CI 29-33%) of workers aware that disease could be transmitted from animals.
The current working conditions in slaughterhouses in western Kenya are not in line with the recommendations of the Meat Control Act of Kenya. Current facilities and practices may increase occupational exposure to disease or injury and contaminated meat may enter the consumer market. The findings of this study could enable the development of appropriate interventions to minimise public health risks. Initially, improvements need to be made to facilities and practices to improve worker safety and reduce the risk of food contamination. Simultaneously, training programmes should target workers and inspectors to improve awareness of the risks. In addition, education of health care workers should highlight the increased risks of injury and disease in slaughterhouse workers. Finally, enhanced surveillance, targeting slaughterhouse workers could be used to detect disease outbreaks. This "One Health" approach to disease surveillance is likely to benefit workers, producers and consumers.
Antibody-based therapeutics and vaccines are essential to combat COVID-19 morbidity and mortality after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Multiple mutations in ...SARS-CoV-2 that could impair antibody defenses propagated in human-to-human transmission and spillover or spillback events between humans and animals. To develop prevention and therapeutic strategies, we formed an international consortium to map the epitope landscape on the SARS-CoV-2 spike protein, defining and structurally illustrating seven receptor binding domain (RBD)–directed antibody communities with distinct footprints and competition profiles. Pseudovirion-based neutralization assays reveal spike mutations, individually and clustered together in variants, that affect antibody function among the communities. Key classes of RBD-targeted antibodies maintain neutralization activity against these emerging SARS-CoV-2 variants. These results provide a framework for selecting antibody treatment cocktails and understanding how viral variants might affect antibody therapeutic efficacy.
Toxoplasma gondii is a zoonotic protozoan parasite infecting warm-blooded animals. Infection in people can occur through ingestion of oocysts passed in the faeces of the definitive hosts; ingestion ...of bradyzoites in the tissue of infected intermediate hosts; or exposure to tachyzoites in raw milk and eggs. Slaughterhouse workers are considered a high-risk group for T. gondii exposure because of their contact with raw meat, although a positive relationship between handling raw meat and T. gondii seropositivity has not been demonstrated in all studies. This study aimed to determine the seroprevalence of antibodies to T. gondii in slaughterhouse workers in Kenya and identify risk factors associated with seropositivity. A survey of slaughterhouse workers was conducted in 142 slaughter facilities in the study area. Information regarding demographics, contact with livestock, meat consumption, and practices in the slaughterhouse was collected using structured questionnaires. Commercial ELISAs were used to detect IgM and IgG antibodies against T. gondii and a multi-level logistic regression model was used to identify potential risk factors for seropositivity in slaughterhouse workers. The apparent prevalence of antibodies to T. gondii was 84.0% (95% Confidence Interval (CI) 81.2-86.5%) for IgG and 2.2% (95% CI 1.3-3.5%) for IgM antibodies. All IgM positive individuals were IgG positive. Risk factors for exposure to T. gondii were: increasing age (Odds Ratio (OR) 1.03; 95% CI 1.01-1.05); owning poultry (OR 2.00; 95% CI 1.11-3.62); and consuming animal blood (OR 1.92; 95% CI 1.21-3.03). The seroprevalence of antibodies to T. gondii was very high in this population and considerably higher than published values in the general population. Risk factors included age, owning poultry and drinking animal blood which were consistent with previous reports but none were specifically associated with working in the slaughterhouse. In this instance slaughterhouse workers may represent a useful sentinel for the general population where the level of exposure is also likely to be high and may signify an unidentified public health risk to vulnerable groups such as pregnant women. A detailed understanding of the epidemiology of infection is required, which should include an assessment of incidence, mortality, and burden since T. gondii infection is likely to have life-long sequelae.
Summary
Reliable modelling of above‐ground net primary production (aNPP) at fine resolution is a significant challenge. A promising avenue for improving process models is to include response and ...effect trait relationships. However, uncertainties remain over which leaf traits are correlated most strongly with aNPP.
We compared abundance‐weighted values of two of the most widely used traits from the leaf economics spectrum (specific leaf area and leaf dry matter content) with measured aNPP across a temperate ecosystem gradient.
We found that leaf dry matter content (LDMC) as opposed to specific leaf area (SLA) was the superior predictor of aNPP (R2 = 0·55).
Directly measured in situ trait values for the dominant species improved estimation of aNPP significantly. Introducing intraspecific trait variation by including the effect of replicated trait values from published databases did not improve the estimation of aNPP.
Our results support the prospect of greater scientific understanding for less cost because LDMC is much easier to measure than SLA.
A lay summary is available for this article.
Lay Summary
Egg‐tempera painting is a pictorial technique widely used in the Middle Ages, although poorly studied in its physico‐chemical aspects until now. Here we show how NMR relaxometry and rheology can be ...combined to probe egg‐tempera paints and shed new light on their structure and behavior. Based on recipes of the 15th century, model formulations with egg yolk and green earth have been reproduced to characterize the physicochemical properties of this paint at the mesoscopic and macroscopic scales. The rheological measurements highlight a synergetic effect between green earth and egg yolk, induced by the interactions between them and the structural organisation of the system. 1H NMR relaxometry emphasizes the presence and the structure of a network formed by the yolk and the pigment.
Crack the code of egg‐tempera paints: The macroscopic and microscopic properties of egg‐tempera paint prepared with green earth are highlighted via rheology and NMR relaxometry.
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