scholarly journals Ideas and perspectives: Heat stress: more than hot air

2016 ◽  
Vol 13 (20) ◽  
pp. 5821-5825 ◽  
Author(s):  
Hans J. De Boeck ◽  
Helena Van De Velde ◽  
Toon De Groote ◽  
Ivan Nijs
Keyword(s):  
Heat Stress ◽  
Air Temperature ◽  
Climate Models ◽  
Heat Waves ◽  
Leaf Temperature ◽  
Balance Model ◽  
Plant Responses ◽  
Atmospheric Conditions ◽  
Air Temperatures ◽  
The Impact

Abstract. Climate models project an important increase in the frequency and intensity of heat waves. In gauging the impact on plant responses, much of the focus has been on air temperatures, while a critical analysis of leaf temperatures during heat extremes has not been conducted. Nevertheless, direct physiological consequences from heat depend primarily on leaf rather than on air temperatures. We discuss how the interplay between various environmental variables and the plants' stomatal response affects leaf temperatures and the potential for heat stress by making use of both an energy balance model and field data. The results demonstrate that this interplay between plants and environment can cause leaf temperature to vary substantially at the same air temperature. In general, leaves tended to heat up when radiation was high and when stomates were closed, as expected. But perhaps counterintuitively, high air humidity also raised leaf temperatures, while humid conditions are typically regarded as benign with respect to plant survival since they limit water loss. High wind speeds brought the leaf temperature closer to the air temperature, which can imply either cooling or warming (i.e. abating or reinforcing heat stress) depending on other prevailing conditions. The results thus indicate that heat waves characterized by similar extreme air temperatures may pose little danger under some atmospheric conditions but could be lethal in other cases. The trends illustrated here should give ecologists and agronomists a more informed indication about which circumstances are most conducive to the occurrence of heat stress.

scholarly journals Ideas and perspectives: Heat stress: more than hot air

2016 ◽  
Author(s):  
Hans J. De Boeck ◽  
Helena Van De Velde ◽  
Toon De Groote ◽  
Ivan Nijs
Keyword(s):  
Heat Stress ◽  
Air Temperature ◽  
Heat Waves ◽  
Balance Model ◽  
Plant Responses ◽  
Atmospheric Conditions ◽  
Change Models ◽  
Wind Speeds ◽  
Air Temperatures ◽  
The Impact

Abstract. Climate change models project an important increase in the frequency and intensity of heat waves. In gauging the impact on plant responses, much of the focus has been on air temperatures while a critical analysis of leaf temperatures during heat extremes has not been made. Nevertheless, direct physiological consequences from heat depend primarily on leaf rather than on air temperatures. We discuss how the interplay between various environmental variables and the plants' stomatal response affects leaf temperatures and the potential for heat stress by making use of both an energy balance model and field data. The results demonstrate that this interplay between plants and environment can cause leaf temperatures fluctuations in excess of 10 °C (for narrow leaves) to even 20 °C (for big broad leaves) at the same air temperature. In general, leaves tended to heat up when radiation was high and when stomates were closed, as expected. But perhaps counterintuitively, also high air humidity raised leaf temperatures, while humid conditions are typically regarded as benign with respect to plant survival since they limit water loss. High wind speeds brought the leaf temperature closer to the air temperature, which can imply either cooling or warming (i.e. abating or reinforcing heat stress) depending on other prevailing conditions. The results thus indicate that heat waves characterized by similar extreme air temperatures may pose little danger under some atmospheric conditions, but could be lethal in other cases. The trends illustrated here should give ecologists and agronomists a more informed indication about which circumstances are most conductive for heat stress to occur.

scholarly journals Trends in heat stress over Europe over the 20th century

2021 ◽  
Author(s):  
Joakim Kjellsson ◽  
Nils Niebaum ◽  
Robin Pilch Kedzierski
Keyword(s):  
Heat Stress ◽  
20Th Century ◽  
Heat Wave ◽  
Air Temperature ◽  
Heat Waves ◽  
Dew Point ◽  
Stress Index ◽  
Internal Climate Variability ◽  
Air Temperatures ◽  
Using Data

<p>We investigate how European heat waves and their associated heat stress on humans have changed over the 20th century. We find that the heat stress has increased, even in regions where heat waves have not become warmer. As heat stress increases over wide areas of Europe there is also an increase in the total population affected by the heat stress. </p><p>Heat waves pose a serious health risk to humans by reducing our ability to shed heat. We have studied the occurrence and intensity of heat waves as well as a heat stress index based on simplified wet-bulb globe temperature using data from ERA-20C reanalysis 1900-2010. Over the 110 years of data we find an overall warming of the air temperatures and dew point. The 98th percentile of both air temperature has increased by more than 1.5°C over large areas of Europe. </p><p>We find an overall increase in heat wave days per year as well as an increase of air temperature during heat waves over most of Europe. As such, many densely populated areas exhibit increased heat stress during heat waves. For example, the mean heat stress during heat wave days over Paris has increased by one level, from “alert” in 1900-1930 to “caution” in 1980-2010. The fraction of the population exposed to heat waves has increased by 10%/century in central Europe and 25%/century over the Mediterranean. </p><p>We find more heat waves during 1920 - 1950, which may be related to the positive phase of the Atlantic Multidecadal Variation (AMV). This suggests that the heat stress during European heat waves may also be influenced by internal climate variability, and large-ensemble model simulations may be used to disentangle the effects of natural variability and anthropogenic forcing.</p>

scholarly journals Using Leaf Temperature to Improve Simulation of Heat and Drought Stresses in a Biophysical Model

Plants ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 8 ◽  
Author(s):  
Ruchika S. Perera ◽  
Brendan R. Cullen ◽  
Richard J. Eckard
Keyword(s):  
Heat Stress ◽  
Air Temperature ◽  
Energy Budget ◽  
Perennial Ryegrass ◽  
Measured Data ◽  
Leaf Temperature ◽  
Biophysical Model ◽  
Controlled Environment ◽  
Air Temperatures ◽  
Environment Experiment

Despite evidence that leaf temperatures can differ by several degrees from the air, crop simulation models are generally parameterised with air temperatures. Leaf energy budget is a process-based approach that can be used to link climate and physiological processes of plants, but this approach has rarely been used in crop modelling studies. In this study, a controlled environment experiment was used to validate the use of the leaf energy budget approach to calculate leaf temperature for perennial pasture species, and a modelling approach was developed utilising leaf temperature instead of air temperature to achieve a better representation of heat stress impacts on pasture growth in a biophysical model. The controlled environment experiment assessed the impact of two combined seven-day heat (control = 25/15 °C, day/night, moderate = 30/20 °C, day/night, and severe = 35/25 °C, day/night) and drought stresses (with seven-day recovery period between stress periods) on perennial ryegrass (Lolium perenne L.), cocksfoot (Dactylis glomerata L.), tall fescue (Festuca arundinacea Schreb.) and chicory (Cichorium intybus L.). The leaf temperature of each species was modelled by using leaf energy budget equation and validated with measured data. All species showed limited homeothermy with the slope of 0.88 (P < 0.05) suggesting that pasture plants can buffer temperature variations in their growing environment. The DairyMod biophysical model was used to simulate photosynthesis during each treatment, using both air and leaf temperatures, and the patterns were compared with measured data using a response ratio (effect size compared to the well-watered control). The effect size of moderate heat and well-watered treatment was very similar to the measured values (~0.65) when simulated using T leaf, while T air overestimated the consecutive heat stress impacts (0.4 and 0). These results were used to test the heat stress recovery function (Tsum) of perennial ryegrass in DairyMod, finding that recovery after heat stress was well reproduced when parameterized with T sum = 20, while T sum = 50 simulated a long lag phase. Long term pasture growth rate simulations under irrigated conditions in south eastern Australia using leaf temperatures predicted 6–34% and 14–126% higher pasture growth rates, respectively at Ellinbank and Dookie, during late spring and summer months compared to the simulations using air temperatures. This study demonstrated that the simulation of consecutive heat and/or drought stress impacts on pasture production, using DairyMod, can be improved by using leaf temperatures instead of air temperature.

scholarly journals Development and Prediction of Selected Temperature and Precipitation Characteristics in Southern Moravia

2014 ◽  
Vol 62 (1) ◽  
pp. 91-98 ◽  
Author(s):  
Petra Fukalová ◽  
Hana Středová ◽  
Kristýna Vejtasová
Keyword(s):  
Air Temperature ◽  
Climate Models ◽  
Heat Waves ◽  
Landscape Management ◽  
Agricultural Activity ◽  
Climatic Data ◽  
Temperature And Precipitation ◽  
Air Temperatures ◽  
South Moravia ◽  
Climatic Characteristics

In recent years, rising temperatures and changes in precipitation patterns have a significant impact on agriculture. This paper presents analyses of selected climatic characteristics of the South Moravian region. The evaluation was based on the data from the Czech Hydrometeorological Institute. Climatic data for future periods were gained using the A1B emission scenario. With regard to the agricultural activity of this region, climatic characteristics (average air temperature, heat waves, average precipitation and periods without precipitation) were selected and compared in the following three periods 1961–1990, 2021–2050 and 2071–2100. The results showed an increase of the average air temperature, increase in the number of tropical days and days in heat waves. It was also found that as a result of rising air temperatures and different distribution of precipitation, the period of drought will significantly prolong in the future. Very unfavourable climate situation is expected in the particular period of 2071–2100 in this region. Increasing drought, predicted by climate models, presents major problem for the agriculture of South Moravia. It is necessary to adapt to these anticipated changes not only in the agricultural activities but also in the landscape management in general.

scholarly journals Interaction between Indoor Occupational Heat Stress and Environmental Temperature Elevations during Heat Waves

2019 ◽  
Vol 11 (4) ◽  
pp. 755-762 ◽  
Author(s):  
Urša Ciuha ◽  
Tjaša Pogačar ◽  
Lučka Kajfež Bogataj ◽  
Mitja Gliha ◽  
Lars Nybo ◽  
...  
Keyword(s):  
Heat Stress ◽  
Heat Wave ◽  
Air Temperature ◽  
Heat Production ◽  
Heat Waves ◽  
Thermal Strain ◽  
Cumulative Effect ◽  
Thermal Conditions ◽  
Manufacturing Productivity ◽  
The Impact

Abstract Occupational heat strain is a public health threat, and for outdoor industries there is a direct influence from elevated environmental temperatures during heat waves. However, the impact in indoor settings is more complex as industrial heat production and building architecture become factors of importance. Therefore, this study evaluated effects of heat waves on manufacturing productivity. Production halls in a manufacturing company were instrumented with 33 dataloggers to track air temperature and humidity. In addition, outdoor thermal conditions collected from a weather station next to the factory and daily productivity evaluated as overall equipment efficiency (OEE) were obtained, with interaction between productivity and thermal conditions analyzed before, during, and after four documented heat waves (average daily air temperature above 24°C on at least three consecutive days). Outdoor (before: 21.3° ± 4.6°C, during: 25.5° ± 4.3°C, and after: 19.8° ± 3.8°C) and indoor air temperatures (before: 30.4° ± 1.3°C, during: 32.8° ± 1.4°C, and after: 30.1° ± 1.4°C) were significantly elevated during the heat waves (p &lt; 0.05). OEE was not different during the heat waves when compared with control, pre-heat-wave, and post-heat-wave OEE. Reduced OEE was observed in 3-day periods following the second and fourth heat wave (p &lt; 0.05). Indoor workers in settings with high industrial heat production are exposed to a significant thermal stress that may increase during heat waves, but the impact on productivity cannot be directly derived from outdoor factors. The significant decline in productivity immediately following two of the documented heat waves could relate to a cumulative effect of the thermal strain experienced during work combined with high heat stress in the recovery time between work shifts.

scholarly journals On the Spatial Patterns of Urban Thermal Conditions Using Indoor and Outdoor Temperatures

2021 ◽  
Vol 13 (4) ◽  
pp. 640
Author(s):  
Sadroddin Alavipanah ◽  
Dagmar Haase ◽  
Mohsen Makki ◽  
Mir Muhammad Nizamani ◽  
Salman Qureshi
Keyword(s):  
Heat Stress ◽  
Air Temperature ◽  
Temperature Data ◽  
Cold Spot ◽  
Temperature Pattern ◽  
Outdoor Temperature ◽  
Residential Units ◽  
Urban Settlements ◽  
The Impact ◽  
Indoor And Outdoor

The changing climate has introduced new and unique challenges and threats to humans and their environment. Urban dwellers in particular have suffered from increased levels of heat stress, and the situation is predicted to continue to worsen in the future. Attention toward urban climate change adaptation has increased more than ever before, but previous studies have focused on indoor and outdoor temperature patterns separately. The objective of this research is to assess the indoor and outdoor temperature patterns of different urban settlements. Remote sensing data, together with air temperature data collected with temperature data loggers, were used to analyze land surface temperature (outdoor temperature) and air temperature (indoor temperature). A hot and cold spot analysis was performed to identify the statistically significant clusters of high and low temperature data. The results showed a distinct temperature pattern across different residential units. Districts with dense urban settlements show a warmer outdoor temperature than do more sparsely developed districts. Dense urban settlements show cooler indoor temperatures during the day and night, while newly built districts show cooler outdoor temperatures during the warm season. Understanding indoor and outdoor temperature patterns simultaneously could help to better identify districts that are vulnerable to heat stress in each city. Recognizing vulnerable districts could minimize the impact of heat stress on inhabitants.

The impact of extreme climatic events on pasture-based dairy systems: a review

2017 ◽  
Vol 68 (12) ◽  
pp. 1158 ◽  
Author(s):  
J. Chang-Fung-Martel ◽  
M. T. Harrison ◽  
R. Rawnsley ◽  
A. P. Smith ◽  
H. Meinke
Keyword(s):  
Climate Change ◽  
Heat Stress ◽  
Heat Waves ◽  
Animal Health ◽  
Adaptation Strategies ◽  
Pasture Production ◽  
Potential Productivity ◽  
Extreme Climatic Events ◽  
Dairy Systems ◽  
The Impact

Extreme climatic events such as heat waves, extreme rainfall and prolonged dry periods are a significant challenge to the productivity and profitability of dairy systems. Despite projections of more frequent extreme events, increasing temperatures and reduced precipitation, studies on the impact of these extreme climatic events on pasture-based dairy systems remain uncommon. The Intergovernmental Panel on Climate Change has estimated Australia to be one of the most negatively impacted regions with additional studies estimating Australian production losses of around 16% in the agricultural sector and 9–19% between the present and 2050 in the south-eastern dairy regions of Australia due to climate change. Here we review the literature on the impact of climate change on pasture-based dairy systems with particular focus on extreme climatic events. We provide an insight into current methods for assessing and quantifying heat stress highlighting the impacts on pastures and animals including the associated potential productivity losses and conclude by outlining potential adaptation strategies for improving the resilience of the whole-farm systems to climate change. Adapting milking routines, calving systems and the introduction of heat stress tolerant dairy cow breeds are some proposed strategies. Changes in pasture production would also include alternative pasture species better adapted to climate extremes such as heat waves and prolonged periods of water deficit. In order to develop effective adaptation strategies we also need to focus on issues such as water availability, animal health and associated energy costs.

scholarly journals Unprecedented Clear Skies Drove Remarkable Melting in Greenland

Eos ◽  
2020 ◽  
Vol 101 ◽  
Author(s):  
Hannah Thomasy
Keyword(s):  
Climate Models ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Atmospheric Conditions ◽  
Current Climate ◽  
The Impact

Scientists are concerned that current climate models do not fully account for the impact of atmospheric conditions on the Greenland Ice Sheet and, consequently, may dramatically underestimate melting.

scholarly journals Modeling Shoot-tip Temperature in the Greenhouse Environment

1998 ◽  
Vol 123 (2) ◽  
pp. 208-214 ◽  
Author(s):  
James E. Faust ◽  
Royal D. Heins
Keyword(s):  
Energy Balance ◽  
Solar Radiation ◽  
Air Temperature ◽  
Flower Development ◽  
Vapor Pressure Deficit ◽  
Shoot Tip ◽  
Balance Model ◽  
Glass Temperature ◽  
Air Temperatures ◽  
Material Temperature

An energy-balance model is described that predicts vinca (Catharanthus roseus L.) shoot-tip temperature using four environmental measurements: solar radiation and dry bulb, wet bulb, and glazing material temperature. The time and magnitude of the differences between shoot-tip and air temperature were determined in greenhouses maintained at air temperatures of 15, 20, 25, 30, or 35 °C. At night, shoot-tip temperature was always below air temperature. Shoot-tip temperature decreased from 0.5 to 5 °C below air temperature as greenhouse glass temperature decreased from 2 to 15 °C below air temperature. During the photoperiod under low vapor-pressure deficit (VPD) and low air temperature, shoot-tip temperature increased ≈4 °C as solar radiation increased from 0 to 600 W·m-2. Under high VPD and high air temperature, shoot-tip temperature initially decreased 1 to 2 °C at sunrise, then increased later in the morning as solar radiation increased. The model predicted shoot-tip temperatures within ±1 °C of 81% of the observed 1-hour average shoot-tip temperatures. The model was used to simulate shoot-tip temperatures under different VPD, solar radiation, and air temperatures. Since the rate of leaf and flower development are influenced by the temperature of the meristematic tissues, a model of shoot-tip temperature will be a valuable tool to predict plant development in greenhouses and to control the greenhouse environment based on a plant temperature setpoint.

Validation of atmospheric reanalyses over the Weddell Sea, Antarctica, using observations from drifting buoys

2021 ◽  
Author(s):  
John King ◽  
Gareth Marshall ◽  
Steve Colwell ◽  
Clare Allen-Sader ◽  
Tony Phillips
Keyword(s):  
Sea Ice ◽  
Austral Summer ◽  
Longwave Radiation ◽  
Weddell Sea ◽  
Balance Model ◽  
Atmospheric Conditions ◽  
Snow Layer ◽  
Near Surface ◽  
The Impact ◽  
Drifting Buoys

&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Global atmospheric reanalyses are frequently used to drive ocean-ice models but few data are available to assess the quality of these products in the Antarctic sea ice zone. We utilise measurements from three drifting buoys that were deployed on sea ice in the southern Weddell Sea in the austral summer of 2016 to validate the representation of near-surface atmospheric conditions in the ERA-Interim and ERA5 reanalyses produced by the European Centre for Medium Range Weather Forecasts (ECMWF). The buoys carried sensors to measure atmospheric pressure, air temperature and humidity, wind speed and direction, and downwelling shortwave and longwave radiation. One buoy remained in coastal fast ice for most of 2016 while the other two drifted northward through the austral winter and exited the pack ice during the following austral summer. Comparison of buoy measurements with reanalysis data indicates that both reanalyses represent the surface pressure field in this region accurately. Reanalysis temperatures are, however, biased warm by around 2 &amp;#176;C in both products, with the largest biases seen at the lowest temperatures. We suggest that this bias is a result of the simplified representation of sea ice in the reanalyses, in particular the lack of an insulating snow layer on top of the ice. We use a simple surface energy balance model to investigate the impact of the reanalysis biases on sea ice thermodynamics.&lt;/p&gt;

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