scholarly journals 3D Numerical Analysis of the Natural Ventilation Behavior in a Colombian Greenhouse Established in Warm Climate Conditions

2020 ◽  
Vol 12 (19) ◽  
pp. 8101
Author(s):  
Edwin Villagran ◽  
Rommel Leon ◽  
Andrea Rodriguez ◽  
Jorge Jaramillo
Keyword(s):  
Relative Humidity ◽  
Agricultural Production ◽  
Food Production ◽  
Natural Ventilation ◽  
Abiotic Factors ◽  
Methodological Approach ◽  
Warm Climate ◽  
Climate Conditions ◽  
Hot Climate ◽  
Global Food

Global food production and availability in hot climate zones are limited by biotic and abiotic factors that affect agricultural production. One of the alternatives for intensifying agriculture and improving food security in these regions is the use of naturally ventilated greenhouses, an alternative that still requires information that allows technical criteria to be established for decision-making. Therefore, the objective of this work was to study the spatial distribution of temperature and relative humidity inside a greenhouse built in the Colombian Caribbean. The methodological approach included the implementation of an experimentally validated 3D numerical simulation model. The main results obtained allowed to determine that the airflows generated inside the greenhouse had average velocities below 0.5 m/s and were mainly driven by the thermal effect of natural ventilation. It was also found that the gradients generated between the interior of the structure and the exterior environment presented values lower than 2.0 °C for temperature and −6.3% for relative humidity. These values can be considered low in comparison with other structures evaluated in other regions of the world where the gradients can reach values higher than 10 °C and 13% for temperature and relative humidity, respectively.

scholarly journals The Water Footprint of Global Food Production

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2696
Author(s):  
Mesfin M. Mekonnen ◽  
Winnie Gerbens-Leenes
Keyword(s):  
Agricultural Production ◽  
Food Production ◽  
Crop Production ◽  
Water Footprint ◽  
Water Productivity ◽  
Blue Water ◽  
Dietary Shifts ◽  
Global Food ◽  
Main Consumer ◽  
Future Population

Agricultural production is the main consumer of water. Future population growth, income growth, and dietary shifts are expected to increase demand for water. The paper presents a brief review of the water footprint of crop production and the sustainability of the blue water footprint. The estimated global consumptive (green plus blue) water footprint ranges from 5938 to 8508 km3/year. The water footprint is projected to increase by as much as 22% due to climate change and land use change by 2090. Approximately 57% of the global blue water footprint is shown to violate the environmental flow requirements. This calls for action to improve the sustainability of water and protect ecosystems that depend on it. Some of the measures include increasing water productivity, setting benchmarks, setting caps on the water footprint per river basin, shifting the diets to food items with low water requirements, and reducing food waste.

Climate change risks to push large parts of global food production and population centres to unprecedented conditions

2020 ◽  
Author(s):  
Matti Kummu ◽  
Matias Heino ◽  
Maija Taka ◽  
Olli Varis ◽  
Daniel Viviroli
Keyword(s):  
Climate Change ◽  
Food Production ◽  
Crop Production ◽  
Ghg Emissions ◽  
Climatic Conditions ◽  
Climate Change Scenarios ◽  
Climate Conditions ◽  
Rcp 8.5 ◽  
Production Areas ◽  
Global Food

<p>The majority of global food production, as we know it, is based on agricultural practices developed within stable Holocene climate conditions. Climate change is altering the key conditions for human societies, such as precipitation, temperature and aridity. Their combined impact on altering the conditions in areas where people live and grow food has not yet, however, been systematically quantified on a global scale. Here, we estimate the impacts of two climate change scenarios (RCP 2.6, RCP 8.5) on major population centres and food crop production areas at 5 arc-min scale (~10 km at equator) using Holdridge Life Zones (HLZs), a concept that incorporates all the aforementioned climatic characteristics. We found that if rapid growth of GHG emissions is not halted (RCP 8.5), in year 2070, one fifth of the major food production areas and one fourth of the global population centres would experience climate conditions beyond the ones where food is currently produced, and people are living. Our results thus reinforce the importance of following the RCP 2.6 path, as then only a small fraction of food production (5%) and population centres (6%) would face such unprecedented conditions. Several areas experiencing these unprecedented conditions also have low resilience, such as those within Burkina Faso, Cambodia, Chad, and Guinea-Bissau. In these countries over 75% of food production and population would experience unprecedented climatic conditions under RCP 8.5. These and many other hotspot areas require the most urgent attention to secure sustainable development and equity.</p>

scholarly journals Influence of the ecological conditions on breeding in closed covered brick barn of black-and-white cows and some ethological reactions

2008 ◽  
Vol 24 (5-6) ◽  
pp. 23-31
Author(s):  
K. Krastev ◽  
K. Boychev
Keyword(s):  
Relative Humidity ◽  
Wind Velocity ◽  
Natural Ventilation ◽  
Abiotic Factors ◽  
Production Environment ◽  
Ecological Conditions ◽  
Black And White ◽  
Milk Cows

This study was done with the aim to establish the season dynamics of ethological indicators: lying, standing, feeding and drinking of milk cows with is result of such abiotic factors as: temperature, relative humidity and wind velocity movement in production environment. The animals were bred during the year in closed covered brick barn with natural ventilation. From the analysis of the received results is clear that the parameters of the ethological reactions are changing in a cycle during the seasons of the year. This is an expression of the reaction towards the influence of the abiotic factors of the environment.

An assessment of different courtyard configurations in urban communities in the United Arab Emirates (UAE)

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Hanan M. Taleb ◽  
Lama Abumoeilak
Keyword(s):  
Relative Humidity ◽  
Urban Communities ◽  
United Arab Emirates ◽  
User Satisfaction ◽  
Natural Ventilation ◽  
Simulation Analysis ◽  
Weather Data ◽  
Base Case ◽  
Content Type ◽  
Hot Climate

PurposeThis paper aims to find ways to optimise the thermal performance of this courtyard design in current urban communities in hot arid regions.Design/methodology/approachThe case study for this research is the Dubai sustainable city residential cluster. After collecting weather data from a site visit, four courtyard configurations were suggested and assessed using ENVI-met simulation analysis software to build a virtual model to represent the base case. This model is used to evaluate the thermal behaviour of outdoor urban spaces. The four courtyard layout scenarios were suggested and tested against the base case model. Scenario one is u-shaped, scenario two is linear, scenario three has central buildings with square courtyards and finally, scenario four has u-shaped buildings with square courtyards.FindingsAll the courtyard scenarios achieved an adequate level of user satisfaction, and the wind speed and distribution affected the relative humidity of the outdoor areas. The main findings indicate that courtyard scenario four provided the best microclimatic behaviour within the urban community, as the relative humidity dropped from 56.27% to 48% and the temperature was reduced from 43.03 °C to 41.03 °C.Research limitations/implicationsThe study was focused on Dubai and on urban levels, but the findings can be generalized to cover most of courtiers that have similar climatic and environmental contexts.Practical implicationsArchitects and urban planners will recognize the potential to reduce energy due to natural ventilation and lower solar radiation.Social implicationsIf the findings be applied, this will lead to energy reduction as well as building foot print reduction.Originality/valueThis paper contributes to the existing literature by comprehensively reviewing the concept of courtyards in hot climate and in a region of shortage of studies conducted. It will draw future recommendations of how and where to design courtyards within urban communities.

One-third of global food production at risk for unprecedented climate conditions due to climate change

2021 ◽  
Author(s):  
Matti Kummu ◽  
Matias Heino ◽  
Maija Taka ◽  
Olli Varis ◽  
Daniel Viviroli
Keyword(s):  
Climate Change ◽  
At Risk ◽  
Food Production ◽  
Crop Production ◽  
Climatic Factors ◽  
Livestock Production ◽  
Climatic Conditions ◽  
Planetary Boundaries ◽  
Climate Conditions ◽  
Global Food

<p>The majority of food production is based on agricultural practices developed for the stable Holocene climatic conditions, which now are under risk for rapid change due to climate change. Although various studies have assessed the potential changes in climatic conditions and their projected impacts on yields globally, there is no clear understanding on the climatic niche of the current food production. Nor, which areas are under risk of falling outside this niche.</p><p>In this study we aim first at defining the novel concept Safe Climatic Space (SCS) by using a combination of three key climatic parameters. SCS is defined here as the climate conditions to which current food production systems (here crop production and livestock production separately) are accustomed to, an analogue to Safe Operating Space (SOS) concepts such as Planetary Boundaries and human climate niche. We use a combination of selected key climatic factors to define the SCS through the Holdridge Life Zone (HLZ) concept. It allows us to first define the SCS based on three climatic factors (annual precipitation, biotemperature and aridity) and to identify which food production areas would stay within it under changed future climate conditions. </p><p>We show that a rapid and unhalted growth of GHG emissions (SSP5-8.5) could force 31% (25-37% with 5th-95th percentile confidence interval) of global food crop production and 34% (26-43%) of livestock production beyond the SCS by 2081-2100. Our results underpin the importance of committing to a low emission scenario (SSP1-2.6), whereupon the extent of food production facing unprecedented conditions would be a fraction: 8% (4-10%) for crop production and 4% (2-8%) for livestock production. The most vulnerable areas are the ones at risk of leaving SCS with low resilience to cope with the change, particularly South and Southeast Asia and Africa’s Sudano-Sahelian Zone. </p><p>Our findings reinforce the existing research in suggesting that climate change forces humanity into a new era of reduced validity of past experiences and dramatically increased uncertainties. Future solutions should be concentrated on actions that would both mitigate climate change as well as increase resilience in food systems and societies, increase the food production sustainability that respects key planetary boundaries, adapt to climate change by, for example, crop migration and foster local livelihoods especially in the most critical areas.</p>

scholarly journals Basal tolerance to heat and cold exposure of the spotted wing drosophila, Drosophila suzukii

2016 ◽  
Author(s):  
Thomas Enriquez ◽  
Hercé Colinet
Keyword(s):  
Relative Humidity ◽  
High Temperatures ◽  
Thermal Tolerance ◽  
Abiotic Factors ◽  
Methodological Approach ◽  
Spotted Wing Drosophila ◽  
Basic Knowledge ◽  
Drosophila Suzukii ◽  
Temperature Dependent ◽  
Cold Tolerant

The spotted wing Drosophila, Drosophila suzukii, is a new pest in Europe and America which causes severe damages to stone fruits crops. Temperature and humidity are among the most important abiotic factors governing insect life. In many situations, temperature can become stressful thus compromising fitness and survival. The ability to cope with thermal stress depends on basal level of thermal tolerance. Basic knowledge on temperature-dependent mortality of D. suzukii is essential to facilitate management of this pest. The objective of the present study was to investigate D. suzukii basal cold and heat tolerance. Adults and pupae were submitted to six low (-5 to 7.5 °C) and seven high temperatures (30 to 37 °C) for various durations, and survival-time-temperature relationships were investigated. In addition, pupal thermal tolerance was analyzed under low vs. high relative humidity. Our results showed that males had higher cold survival than females, and pupae appeared less cold-tolerant than adults. Above 5 °C, adult cold mortality became minor, even after prolonged exposures (i.e. one month). Males were less heat tolerant than females, and pupae showed a better survival to extreme high temperatures than adults. Low relative humidity did not affect D. suzukii cold survival, but reduced survival under heat stress. Overall, this study shows that survival of D. suzukii under heat and cold conditions depends on both stress intensity and duration, and the methodological approach used here, which was based on thermal tolerance landscapes, provides a comprehensive description of D. suzukii thermal tolerance and limits.

scholarly journals Basal tolerance to heat and cold exposure of the spotted wing drosophila, Drosophila suzukii

2016 ◽  
Author(s):  
Thomas Enriquez ◽  
Hercé Colinet
Keyword(s):  
Relative Humidity ◽  
High Temperatures ◽  
Thermal Tolerance ◽  
Abiotic Factors ◽  
Methodological Approach ◽  
Spotted Wing Drosophila ◽  
Basic Knowledge ◽  
Drosophila Suzukii ◽  
Temperature Dependent ◽  
Cold Tolerant

The spotted wing Drosophila, Drosophila suzukii, is a new pest in Europe and America which causes severe damages to stone fruits crops. Temperature and humidity are among the most important abiotic factors governing insect life. In many situations, temperature can become stressful thus compromising fitness and survival. The ability to cope with thermal stress depends on basal level of thermal tolerance. Basic knowledge on temperature-dependent mortality of D. suzukii is essential to facilitate management of this pest. The objective of the present study was to investigate D. suzukii basal cold and heat tolerance. Adults and pupae were submitted to six low (-5 to 7.5 °C) and seven high temperatures (30 to 37 °C) for various durations, and survival-time-temperature relationships were investigated. In addition, pupal thermal tolerance was analyzed under low vs. high relative humidity. Our results showed that males had higher cold survival than females, and pupae appeared less cold-tolerant than adults. Above 5 °C, adult cold mortality became minor, even after prolonged exposures (i.e. one month). Males were less heat tolerant than females, and pupae showed a better survival to extreme high temperatures than adults. Low relative humidity did not affect D. suzukii cold survival, but reduced survival under heat stress. Overall, this study shows that survival of D. suzukii under heat and cold conditions depends on both stress intensity and duration, and the methodological approach used here, which was based on thermal tolerance landscapes, provides a comprehensive description of D. suzukii thermal tolerance and limits.

Effect of Wet Curing and Hot Climate on Strength and Durability of SCC with Natural Pozzolan

2020 ◽  
Vol 13 (1) ◽  
pp. 58-73
Author(s):  
Youcef Guettaf ◽  
Said Kenai ◽  
Jamal Khatib ◽  
Walid Yahiaoui
Keyword(s):  
Relative Humidity ◽  
Middle Eastern ◽  
Capillary Absorption ◽  
Concrete Durability ◽  
Natural Pozzolan ◽  
Climate Conditions ◽  
Hot Climate ◽  
Negative Effect ◽  
Summer Time ◽  
Strength And Durability

Aims: The aim of this study is to discuss the performance of SCC with natural pozzolana under hot climate conditions. Background: The performance of vibrated concrete under hot climate is well investigated. However, the effect of hot climate on SCC is tittle investigated. North African and Middle Eastern countries are subjected to hot and dry environments especially during summer periods. Hence there is a need to investigate the performance of SCC under hot climate. Objective: The objective of this paper is to study the effect of water curing duration followed by natural hot climate exposure on the performance of SCC with Natural Pozzolan (NP). Methods: It is an experimental investigation where Concrete specimens were exposed to a standard curing environment (relative humidity RH = 100% and Temperature T°= 20°C ± 2°C) for 0, 1, 3, 7, 14 and 28 days, followed by a second cure in a hot environment in open air on a laboratory terrace in North Africa area during summer time with a temperature of 35°C to 45°C and a relative humidity of 65% to 75%. The cement was substituted by NP in weigh at three substitution levels (0%, 15% and 25%). Results: The experimental results show the importance of the wet curing in hot climate, especially when NP is used. Substituting cement by NP improves the self-compacting concrete durability for the long term. Conclusion: The substitution of cement by natural pozzolan reduced water permeability and capillary absorption. The hot climate has no negative effect on the evolution of the mechanical strength and durability of the SCC with natural pozzolan when undergoing a long initial wet cure.

Phosphorus: Past History and Contributions to the Global Food Supply

2019 ◽  
Vol 103 (1) ◽  
pp. 6-8 ◽  
Author(s):  
Terry Roberts
Keyword(s):  
Food Security ◽  
Food Supply ◽  
Food Production ◽  
Production Systems ◽  
Past History ◽  
Phosphate Fertilizer ◽  
Global Food ◽  
Global Food Supply

Since its early rudimentary forms, phosphate fertilizer has developed in step with our understanding of successful food production systems. Recognized as essential to life, the responsible use P in agriculture remains key to food security.

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