Structures, gelatinization properties and enzyme hydrolyses of starches from transparent and floury grains of rices subjected to field natural extreme high temperature.

Three rice varieties underwent the field natural extreme high temperature (EHT) with daily average temperature over 30 °C from 21 to 89 days after sowing, and had transparent, chalky and floury grains. The structures, gelatinization properties and enzyme hydrolyses of starches from transparent and floury grains were investigated. Compared with control transparent grains, floury grains subjected to EHT markedly decreased the contents of amylose molecules, amylopectin A chains and amylopectin B1 chains and increased the contents of amylopectin B2 and B3+ chains and the average branch-chain length of amylopectin. Both transparent and floury grains had A-type starches, but floury grain starches exhibited higher relative crystallinity, gelatinization temperature, retrogradation and pasting viscosities than transparent grain starches. Floury grain starches had lower hydrolysis rates than transparent grain starches. Native starches were more resistant to digestion but gelatinized and retrograded starches were more prone to digestion in floury grains than in transparent grains.

Impact of extreme high temperatures on pollution emissions of enterprise: Evidence from China.

Frequently occurring extreme weather events can pose a challenge to people and production systems. Coping with extreme high temperatures requires promoting the synergy between pollution reduction and carbon reduction. Accordingly, this study examines the causal relationship between extreme high temperatures and corporate pollution emissions by using the panel data of a Chinese sample from 2000 to 2014. This study uses fixed-effects models for the analysis. Baseline results show that a unit increase in the standardized temperature will result in a 4.6% reduction in corporate pollutant emissions. The heterogeneous analysis shows that extreme high temperatures will have an obvious effect on enterprises with low financing constraints and high policy and public constraints as well as on enterprises in cities with a high level of economic development, in innovative cities, and in the eastern region. We also explore the mechanism through which extreme high temperatures reduce pollutant emissions from the two dimensions of external environmental pressure and internal environmental governance. Extreme high temperatures will prompt enterprises to improve their energy efficiency, engage in innovative production processes, adopt source-and-end governance measures, and curb their pollutant emissions while strengthening government environmental supervision. This study provides new ideas for enterprise pollution reduction and serves as an inspiration to the government in formulating environmental policies.

In-situ supplementary irrigation device for afforestation under extreme high temperature: An exploration in North China.

Afforestation plays a crucial role in environmental management for many countries. Yet, frequently extreme high temperature (EHT) events in arid and semi-arid regions easily cause the death of artificially planted saplings. To address this, we present a new in-situ supplementary irrigation device (SID) consisting of a rainwater catching board, a storage tank, and ceramic emitters. A continuous EHT experiment combined with the HYDRUS-2D model in North China is further conducted to investigate the soil water-heat properties of the in-situ SID and the growth performance of the planted saplings (Platycladus orientalis) under EHT. The results show that in-situ SID keeps a stable and suitable soil water-heat status in the root layer of the planted saplings under EHT. Especially, the in-situ SID with one ceramic emitter maintains the soil water moisture in a narrow and suitable range from 0.149 cm3 cm-3 to 0.153 cm3 cm-3, and reduces the maximum soil temperature by 2.7 °C compared to the traditional irrigation method. Furthermore, the in-situ SID with one ceramic emitter presents the highest average leaf water content (66.9%), new shoot (35.0 mm), and tree height (62.0 mm). The economic benefit analysis finds that the in-situ SID provides a shorter time to recover high funds and saves a large amount of irrigation water resources. Overall, this study provides an effective irrigation device for forest managers to improve the ecological service effectiveness of afforestation in areas with frequent EHT events and scarce water resources.

Extreme high temperatures and corporate low-carbon actions.

Greenhouse gas emissions are considered the culprit of extreme high temperatures, and low-carbon transformation has become a global consensus. The low-carbon action by enterprises is an inevitable choice if they are to adapt to economic and social needs. Green innovation is an important measure for enterprises to respond to the challenges of low-carbon transformation. This study mainly discusses the causal relationship between extreme high temperatures and green innovation of enterprises. Using China's industrial enterprise database, we construct county-annual panel data from 2000 to 2013. Results show that extreme high temperatures improve the level of green innovation of enterprises. After a series of robustness tests, the results remain. Mechanism analysis shows that extreme high temperatures increase the environmental concerns of the government, the public, and society, thus strengthening government regulation, public participation, and social supervision as well as encouraging enterprises to carry out green innovation. Our heterogeneous analysis shows that in the eastern region with a high level of legal system and economic development, it is easier to promote green innovation for enterprises. In addition, large-scale enterprises are more willing to carry out green innovation after experiencing a heat wave.

Effect of extreme high temperature on cognitive function at different time scales: A national difference-in-differences analysis.

BACKGROUND: Mounting evidence has demonstrated that high temperature was associated with adverse health outcomes, especially morbidity and mortality. Nonetheless, the impact of extreme high temperature on cognitive performance, which is the fundamental capacity for interpreting one's surroundings, decision-making, and acquiring new abilities, has not been thoroughly investigated. METHODS: We aimed to assess associations between extreme high temperature at different time scales and poor cognitive function. We used longitudinal survey data from the three waves of data from China Family Panel Study, providing an 8-year follow-up of 53,008 participants from China. We assessed temperature and extreme high temperature exposure for each participant based on the residential area and date of cognitive test. We defined the proportion of days/hours above 32 °C as the metric of the exposure to extreme high temperature. Then we used generalized additive model and difference-in-differences approach to explore the associations between extreme high temperature and cognitive function. RESULTS: Our results demonstrated that either acute exposure or long-term exposure to extreme high temperature was associated with cognitive decline. At hourly level, 0-1 hour acute exposure to extreme high temperature would induce -0.93 % (95 % CI: -1.46 %, -0.39 %) cognitive change. At annual level, 10 percentage point increase in the hours proportion exceeding 32 °C in the past two years induced -9.87 % (95 % CI: -13.99 %, -5.75 %) cognitive change. Furthermore, subgroup analyses indicated adaptation effect: for the same 10 percentage increase in hours proportion exceeding 32 °C, people in warmer areas had cognitive change of -6.41 % (-11.22 %, -1.61 %), compared with -15.30 % (-21.07 %, -9.53 %) for people in cool areas. CONCLUSION: Our results demonstrated that extreme high temperature was associated with reduced cognitive function at hourly, daily and annual levels, warning that people should take better measures to protect the cognitive function in the context of climate change.

Competition Increases Risk of Species Extinction during Extreme Warming.

AbstractTemperature and interspecific competition are fundamental drivers of community structure in natural systems and can interact to affect many measures of species performance. However, surprisingly little is known about the extent to which competition affects extinction temperatures during extreme warming. This information is important for evaluating future threats to species from extreme high-temperature events and heat waves, which are rising in frequency and severity around the world. Using experimental freshwater communities of rotifers and ciliates, this study shows that interspecific competition can lower the threshold temperature at which local extinction occurs, reducing time to extinction during periods of sustained warming by as much as 2 weeks. Competitors may lower extinction temperatures by altering biochemical characteristics of the natural environment that affect temperature tolerance (e.g., levels of dissolved oxygen, nutrients, and metabolic wastes) or by accelerating population decline through traditional effects of resource depletion on life history parameters that affect population growth rates. The results suggest that changes in community structure in space and time could drive variability in upper thermal limits.

Maternal exposure to extreme high-temperature, particulate air pollution and macrosomia in 14 countries of Africa.

BACKGROUND: Macrosomia has increased rapidly worldwide in the past few decades, with a huge impact on health. However, the effect of PM2.5 and extreme high-temperature (EHT) on macrosomia has been ignored. OBJECTIVE: This study aimed to explore the association between maternal exposure to EHT, PM2.5 and macrosomia based on the Seventh Demographic and Health Survey (DHS) in 14 countries of Africa. METHODS: The study included detailed demographic information on 106 382 births and maternal. Satellite inversion models estimated monthly mean PM2.5 and mean surface temperature of 2 m (SMT2m ). Macrosomia was defined as the birth weight ≥ 4000 g. We used a Cox proportional risk regression model to estimate the association between PM2.5 , EHT and macrosomia. We further explored the susceptibility of exposure to EHT and PM2.5 at different pregnancy periods to macrosomia, and plotted the expose-response curve between PM2.5 and macrosomia risk using a restricted cubic spline function. In addition, the Interplot model was used to investigate the interaction between EHT and PM2.5 on macrosomia. Finally, some potential confounding factors were analysed by stratification. RESULTS: There was the positive association between EHT, PM2.5 and macrosomia, and the risk of macrosomia with the increase in concentrations of PM2.5 without clear threshold. Meanwhile, EHT and PM2.5 had a higher effect on macrosomia in middle/later and early/middle stages of pregnancy, respectively. There was a significant interaction between EHT and PM2.5 on macrosomia. CONCLUSIONS: Maternal exposure to EHT, PM2.5 during pregnancy was associated with an increased risk of macrosomia in Africa.

Intensity-duration-frequency relationship of WBGT extremes using regional frequency analysis in South Korea.

The risk levels of heat-related extreme events need to be estimated for prediction and real-time monitoring to mitigate their impacts on air quality, public health, the ecosystem, and critical infrastructure. Many countries have adopted meteorological variable base thresholds for assessing the risk level of heat-related extreme events. These thresholds provide an approximate risk level for a specific event but do not consider its intensity and duration in the risk assessment. The current study provides a statistical tool to assess the risk of heat-related extreme events while concurrently considering their intensities and durations based on the wet-bulb globe temperature (WBGT). To this end, the intensity-duration-frequency (IDF) relationship of the extreme WBGT in South Korea was derived. Regional frequency analysis was employed to understand the IDF relationship. Return levels of heat-related extreme events in South Korea were calculated and their characteristics were investigated based on the annual maximum WBGT observations. The results showed that the IDF relationship could provide the risks of heat-related extreme events while concurrently considering their intensities and durations. The extreme WBGT in South Korea was used to categorize two regions such as coastal and inland based on their statistical characteristics. The return levels of the annual maximum WBGT events were found to vary largely by location. The return levels corresponding to 32 °C with 3-h duration for stations in the coastal and inland regions ranged from 1- to 100-years and 3- to 1000-years, respectively. Mean values of return levels for heatwave events in Seoul, Incheon, Daejon, Gwangju, Daegu, and Busan were 2.8-, 8.4-, 15.3-, 2.8-, 1.6-, and 2.2-years, respectively. The return levels of heatwaves for the warmer cities are smaller than those for cooler cities. The return levels of the heatwave events in South Korea showed a significant increasing trend in several cities, supporting the notion that the impact of heatwave events on South Korea might become more severe in the future.

Regional Temperature Response in Central Asia to National Committed Emission Reductions.

National committed greenhouse gas emission reduction actions are the center of the Paris Agreement, and are known as 'Intended Nationally Determined Contributions' (INDC) that aim to slow down global warming. The climate response to INDC emission reduction is a focus in climate change science. In this study, data from 32 global climate models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) were applied to investigate the changes in the mean and extreme high temperatures in Central Asia (CA) under the INDC scenario above the present-day level. The results show that the magnitude of warming in CA is remarkably higher than the global mean. Almost all the regions in CA will experience more intense, more frequent, and longer-lasting extreme high-temperature events. In comparison with the INDC scenario, the reduced warming of the 2.0 °C/1.5 °C target scenarios will help avoid approximately 44-61%/65-80% of the increase in extreme temperature events in terms of the intensity, frequency, and duration in CA. These results contribute to an improved understanding of the benefits of limiting global warming to the 2.0 °C/1.5 °C targets, which is paramount for mitigation and adaptation planning.

Perceptions of Health Risks from Hot Weather, and Coping Behaviors among Ethnic Minority Groups in Mountain Areas of China: A Case Study in the Tujia and Miao Autonomous Prefecture.

Limited research focuses on risk perceptions of hot weather among ethnic minority groups in remote mountain areas of China. Adopting a multi-stage sampling method, this study received completed questionnaires from 643 participates in Enshi Tujia and Miao Autonomous Prefecture of China in 2017 and 2018. We used multivariate logistic regression models to explore the factors affecting risk perceptions and coping behaviors with regards to hot weather. Results showed that despite a relatively high level of risk perception, the study population in the mountain areas of China had a very low level of preparedness in responding to the risks from heat, and a lack of professional health knowledge in general. In particular, 61.3% (95% CI: 57.1%-5.6%) of the participants felt increasing temperatures in recent years, 73.2% (95% CI: 69.3%-7.0%) thought extreme high temperatures would be a health threat, and 61.3% (95% CI: 57.1%-5.4%) reported physical discomfort during hot weather. However, only 12% (95% CI: 9.5%-4.5%) had the information or knowledge to stay healthy during the extreme high temperatures, and only 24.2% had (95% CI: 20.8%-7.6%) preparation. The logistic regression models suggested that ethnic group, health status, marital status, gender, and employment could affect their perceptions, which could significantly affect the adoption of coping behaviors. In conclusion, our findings have significant implications for developing policies and health education and promotion programs for ethnic minorities in remote regions to maintain good health during hot weather.

[Multi-temporal scale analysis of impacts of extreme high temperature on net carbon uptake in subtropical coniferous plantation.] / 极端高温对亚热带人工针叶林净碳吸收影响的多时间尺度分析.

Extreme high temperature is one of important extreme weathers that impact forest ecosystem carbon cycle. In this study, applying CO2 flux and routine meteorological data measured during 2003-2012, we examined the impacts of extreme high temperature and extreme high temperature event on net carbon uptake of subtropical coniferous plantation in Qianyanzhou. Combining with wavelet analysis, we analyzed environmental controls on net carbon uptake at different temporal scales, when the extreme high temperature and extreme high temperature event happened. The results showed that mean daily cumulative NEE decreased by 51% in the days with daily maximum air temperature range between 35 ℃ and 40 ℃, compared with that in the days with the range between 30 ℃ and 34 ℃. The effects of the extreme high temperature and extreme high temperature event on monthly NEE and annual NEE related to the strength and duration of extreme high tempe-rature event. In 2003, when strong extreme high temperature event happened, the sum of monthly cumulative NEE in July and August was only -11.64 g C·m-2·(2 month)-1. The value decreased by 90%, compared with multi-year average value. At the same time, the relative variation of annual NEE reached -6.7%. In July and August, when the extreme high temperature and extreme high temperature event occurred, air temperature (Ta) and vapor press deficit (VPD) were the dominant controller for the daily variation of NEE. The coherency between NEE Ta and NEE VPD was 0.97 and 0.95, respectively. At 8-, 16-, and 32-day periods, Ta, VPD, soil water content at 5 cm depth (SWC), and precipitation (P) controlled NEE. The coherency between NEE SWC and NEE P was higher than 0.8 at monthly scale. The results indicated that atmospheric water deficit impacted NEE at short temporal scale, when the extreme high temperature and extreme high temperature event occurred, both of atmospheric water deficit and soil drought stress impacted NEE at long temporal scales in this ecosystem.

Impact of extreme high temperature on mortality and regional level definition of heat wave: a multi-city study in China.

BACKGROUND: Few multi-city studies have been conducted to explore the regional level definition of heat wave and examine the association between extreme high temperature and mortality in developing countries. OBJECTIVES: The purpose of the present study was to investigate the impact of extreme high temperature on mortality and to explore the local definition of heat wave in five Chinese cities. METHODS: We first used a distributed lag non-linear model to characterize the effects of daily mean temperature on non-accidental mortality. We then employed a generalized additive model to explore the city-specific definition of heat wave. Finally, we performed a comparative analysis to evaluate the effectiveness of the definition. RESULTS: For each city, we found a positive non-linear association between extreme high temperature and mortality, with the highest effects appearing within 3 days of extreme heat event onset. Specifically, we defined individual heat waves of Beijing and Tianjin as being two or more consecutive days with daily mean temperatures exceeding 30.2 °C and 29.5 °C, respectively, and Nanjing, Shanghai and Changsha heat waves as ≥3 consecutive days with daily mean temperatures higher than 32.9 °C, 32.3 °C and 34.5 °C, respectively. Comparative analysis generally supported the definition. CONCLUSIONS: We found extreme high temperatures were associated with increased mortality, after a short lag period, when temperatures exceeded obvious threshold levels. The city-specific definition of heat wave developed in our study may provide guidance for the establishment and implementation of early heat-health response systems for local government to deal with the projected negative health outcomes due to heat waves.