Leading to rising temperatures and increasing climate variability, including more frequent and severe extreme weather events (EWE) [1
], the global impacts of climate change on agricultural and food systems are substantial, putting food security and the livelihoods of many at risk [2
]. As the climate becomes more volatile, some parts of the world are projected to be profoundly affected by the intensity of extreme cold events, which are expected to persist late into the 21st century [4
]. Climate-change-related extreme events impose substantial economic and social burdens to global society [5
], particularly in developing countries [6
]. Consequently, to reduce the social and economic burden, it is essential to understand how weather or climate, as well as social and economic factors, interact to influence the nature and implications of climate impacts, and to identify adaptation gaps and implement cost-effective strategies [5
While there are many studies on climate change impacts, such as the impact of floods on health [7
], there is still little research on the social (health) and economic (labour productivity loss) effects of extreme temperature in farming communities. Rather, studies have focused on the damage from severe disasters such as floods and tsunamis [9
]. However, slow onset climate-change-related events such as heat waves and cold spells, while not immediately deadly [11
], can compromise farmers’ health and capacity to work.
Heat waves are anticipated to become more common, last longer and have greater intensity [12
]. Extreme heat can result in health issues ranging from mild heat stress symptoms, such as headaches and fatigue, to severe heat strokes and fainting [13
]. Extreme heat can also lead to death during and after heat waves [15
], and can impair mental capabilities [17
]. Heat stress is considered to be a combination of an external thermal environment and the internal heat generated by physical activity [18
]. When temperatures exceed more than 98.6 °F (37 °C), sweating is the primary mechanism of cooling down the body, but it is impaired by high air humidity, thereby creating heat-related health problems [19
While climate change literature, including the Intergovernmental Panel on Climate Change (IPCC) Report 2014, strongly focuses on the increase of warm temperatures, it has remained silent on the health impact of cold spells [20
]. Cold temperatures and cold spells are also on the rise in some areas as climate variability increases [21
]. Stress on the human body from extreme cold can cause death from hypothermia. According to an international study analysing over 74 million deaths in 384 locations across 13 countries, extreme cold kills 20 times more people than extreme heat [22
]. In many countries, the temperature does not reach such extreme lows, and, for the most part, people utilise behavioural thermoregulation in the cold [23
]. However, there may be situations where these behaviours are inadequate, such as when impoverished people cannot afford adequate clothing or do not have access to heating.
As with heat, extreme cold can also negatively affect the health system, through increases in the occurrence of viral flu, cough, cold diarrhoea, asthma, pneumonia, and other respiratory problems [24
]. In the cold, vasoconstriction and lowering of tissue temperatures cause numbness, which reduces manual dexterity and strength [19
]. Extreme cold can also cause cardiovascular diseases, although to a lesser extent than in cases of heat [26
], while older, marginalised and underprivileged people are the most affected by extreme cold [27
]. The risk of suffering frostbite, for example, increases with age [28
]. Unintended cold exposure can also lead to various health hazards and mortality for those people working outdoors, or more impoverished people who cannot afford indoor heating [29
Extreme heat and cold have impacts on workers’ daily activities and work, which require proper coping mechanisms to minimise the impacts of extreme temperatures. Temperatures of 90 °F (32.22 °C) and above or 50 °F (10 °C) and below can detrimentally affect work performance [31
]. Exposure to extreme and prolonged heat has led to reduced worker enthusiasm and performance at their work; at the same time, a natural reaction of self-pacing working activities to maintain inner core body temperature will reduce working capacity and lower workers’ productivity [18
]. There is an extensive body of literature assessing labour productivity losses from the heat in outdoor and labour intense sectors, such as agriculture [25
], mining [18
] and construction [43
] and cold [47
] can also lead to increased accident rates of outdoor workers. Recent studies have shown that even the urban population is under extreme heat stress and feels impaired in their daily activities and work, particularly in countries where air-conditioning is still under-used [48
]. While few studies have investigated the impacts of climate-change-related extreme cold on outdoor workers’ performance and labour productivity [49
] and their adaptation strategies against cold spells [51
], it has been found that extreme cold causes an unpleasant sensation and thermal discomfort. Discomfort may be a distracting factor reducing work performance through the loss of concentration and alertness, and may also cause physical injuries and accidents in the workplace [49
This study aims to assess the social and economic impacts of climate change using a case study from Nepal. We specifically aimed to (1) assess the impacts of heat waves and cold spells on farmers’ health and levels of heat and cold stress, (2) to explore which factors determine productivity losses, and (3) to reveal the strategies that farmers follow to relieve heat and cold stress and labour productivity loss from extreme temperature.
We used self-reported measures of health and productivity loss, obtained from a survey conducted among 350 farmers in the Terai lowlands in Nepal. This region is considered to be the ‘food bowl’ of the country, and significantly contributes to the national economy. Based on the data source of the Disaster Information Management System (DISINVENTAR) of the United Nations Office for Disaster Risk Reduction (UNISDR), throughout Nepal, 647 cases of cold spells and 49 heat cases of heat waves were reported from 1970 to 2013 [52
]. During this time, 822 cold-related and 49 heat-wave-related deaths were recorded. Of these cold-related deaths, 89% percent of deaths took place in the Terai region. The government of Nepal has identified 30 different types of disaster [53
]; among these disaster events, the cold spell is considered to be the crucial extreme events that caused the significant damage to agriculture, livestock and human beings. During 1970–2013, economic loss from cold spells was US $
835 million, 269,000 Ha of crop land were damaged and 732 cattle were lost due to cold spells [52
]. The effect of cold spells has been found to be higher in the low lying Terai region than in the mountain regions, where there is cold in most of the time, but it is not so significant because the population is both sparse and more adapted to the cold climate [54
]. On the other hand, the impact of cold is severe in Terai, where the largest share of the population resides, most of them living below the poverty line [54
]. Pradhan, Sharma and Pradhan [54
] further reported that cold-wave-related deaths increased at the rate of 13% per annum during 1970–2013. So far, there has been only one study from Nepal [55
] on how working people in the Terai region respond to heat waves. They concluded that males were found to be highly affected by heat waves, and only a few workers had adapted to using heat wave coping mechanisms.
3.1. Sample Description
The average age of the respondents was 38.7 years (SD: 13). Approximately 62% were male, and ~67% had some formal education (Table 2
). The average household size was 7.8 persons (SD: 5.31), and farmers’ average experience in the agricultural sector was 21.2 years (SD: 12.6). Among the total respondents, nearly 38% were female, and nearly one third of the total respondents never attended school, while ~32% had completed high school.
The mean household monthly expenditure was NPR 16,130 (USD = NPR 107.10, source: https://www.nrb.org.np/fxmexchangerate.php
, 8 June 2017) (SD: 18000), which was less than the national monthly household expenditure of NPR 25,928 in 2016 [104
]. Income was equally distributed among the categories (Table 2
Nearly 33% of households reported that they had access to actual weather information. The average land holding was 1.42 Bigga (1 Bigga = 0.6772 ha), and 75% of respondents owned their land. About 53% of farmers perceived their health as good and only 4% as poor. Approximately 16% of respondents reported that they were a little stressed during heat waves (‘low levels’), ~38% moderately, and ~47% severely stressed. Similarly, approximately 15% were a little cold stressed, ~45% moderately cold stressed, and ~ 41% were severely cold stressed. When comparing the means of various independent variables across the two study districts by using t-tests (Table 2
), significant mean differences were observed in all the variables except cold spell perception, level of perceived heat stress and satisfaction with existing health status.
3.2. Heat- and Cold-Related Illnesses and Injuries
Thirty seven per cent of respondents had experienced heat-related health problems and 34% cold-related problems in the last five years, from 2012 to 2017. Respondents made distinctions of diseases and symptoms based on winter and summer seasons. Nearly half of respondents thought that their health condition had been negatively affected during heat waves (48%) and cold spells (51%). About 8% of respondents had been highly affected by both cold spells and heat waves. Only 4% and 3% of respondents, respectively, reported without a doubt that their health had not been impacted by heat and cold.
Those farmers’ who experienced extreme heat- and cold-related illnesses were further asked about their experience. On average, farmers reported three heat-related and two cold-related illnesses. The most commonly reported illness relating to heat was fatigue (73%), followed by dizziness (63%), headaches (41%), nausea (28%), confusion (24%), heat rashes (12%), fainting (8%), loss of concentration (8%) and heat strokes (2%). Joint pains (74%), pneumonia and respiratory problems (74%), and cough and indigestion (22%) were the main illnesses relating to extreme cold (Figure 3
3.3. Determinants of Farmers Perceived Heat and Cold Stress
The results from the ordered logit model showed that farmers with access to actual weather information were less likely to report heat (p
< 0.01) and cold (p
< 0.01) stress than those without this information (Table 3
). Owning livestock had a significant positive impact on perceived heat (p
< 0.1) and cold stress (p
< 0.05). Respondents who perceived an increament in the frequencies of heat waves and cold spells were more likely to have reported higher heat (p
< 0.01) and cold stress levels (p
< 0.01). Farmers who had implemented more heat wave and cold spell adaptation measures in the past were more heat (p
< 0.01) and cold stressed (p
< 0.05) and health (p
< 0.01) had significant positive impacts on the perceived levels of heat, but not cold, stress. Farmers from urban areas reported higher cold stress levels (p
< 0.01) than those from rural areas, while farmers who worked more days outdoors in agricultural activities during the summer season reported higher heat stress (p
< 0.1). District level analysis of determinants of farmers perceived levels of heat and cold stress also presented in the supplementary Table S2
3.4. Labour Productivity Loss during Heat Waves and Cold Spells
Farmers’ perceived heat and cold stress levels, and the number of associated illnesses or symptoms, to significantly increase labour productivity loss during heat waves (p
< 0.05) and cold spells (p
< 0.05) (Table 4
). Farmers in urban areas were more likely to report productivity losses during heat waves (p
< 0.01) and cold spells (p
< 0.01) than farmers in rural areas. Respondents who had access to actual weather information were more likely to perceive labour productivity loss from heat waves (p
< 0.01) and cold spells (p
< 0.01) than those without this information. Respondents who had implemented more heat wave (p
< 0.01) and cold spell (p
< 0.1) adaptation measures (such as clothing adjustment, rescheduling working times, rest breaks) in the past were more likely to perceive labour productivity loss during heat waves and cold spells.
More variables affected farmers’ productivity loss during cold spells than during heat waves. Respondents with higher annual income (p
< 0.05) were more likely to report labour productivity loss during cold spells than those with lower income. Male respondents were less likely to perceive labour productivity loss from cold spells than female respondents. Age was significant (p
< 0.05) and positive, but negative when squared (p
< 0.05), which indicates that reported labour productivity loss increased with age but decreased eventually. District level analyses of self-reported labour productivity loss from extreme temperature are shown in the supplementary Table S3
About 31% (32%) of household heads stated they had been absent from field work during cold spells (heat waves). Those who reported absenteeism during heat waves, had, on average, missed 16 days of farm work during the past year. The average number of absent days during cold spells was 11.5 during the past year. At the same time, about 85% of respondents reported that more than 50% of their work time was less productive during heat waves, and 64% of respondents reported that more than half of their working hours were less productive during cold spells. It could be that cold spells normally occur during the winter season when agricultural activities are limited.
3.5. Adaptation and Relief Strategies to Cope with Heat and Cold Stress
Nearly 96% of respondents said that they wear broad-brimmed hats or used umbrellas to protect themselves from extreme heat when working on the farm. Some 93% of respondents who were heat stressed reported heat relief measures, such as resting in the shade and slowing down their working pace, while ~61% stopped their outdoor farm activities during extreme heat waves. Nearly 65% of respondents rescheduled their working shifts to moderate the impact risks of heat on their health and labour productivity. Approximately 17% of respondents adopted cooling techniques when working outside on very hot days, while ~54% stated that they had different means to cool down, such as drinking more cold water, staying in sheds, staying inside the house, and using wet clothing to reduce the impacts of heat.
Of those respondents (285) who wanted to shift their working schedules, 17% preferred to start and finish earlier, and only about 1% preferred to start and finish later. About 82% wanted to work early in the morning and late in the evening on very hot days to avoid the hottest hours. About 12% did not change their working plans at all, 22% changed their plans rarely, 61% changed sometimes, and 6% often or very often. About 42% of the respondents regularly hired additional labourers to get the work done during hot days, and further reported that nearly all those respondents found their labourers to be less productive during very hot days.
Similarly, to avoid and mitigate the impacts of extreme cold, farmers used the following adaptation measures: wearing warm clothes (99%), cessation of work if the temperature dropped or resting to warm up (82%), rescheduling working timetables (82%), and drinking hot beverages (65%). Of those who rescheduled their working times, most (94%) preferred to work in the daytime during very cold days. Stopping work (χ2 (2) = 5.035, p = 0.0807) and rescheduling working time (χ2 (2) = 10.39, p = 0.0055) were the two heat-related responses most affected by the level of heat stress farmers experienced.
Less stressed farmers were less likely to stop working, or to reschedule their working schedules, than highly stressed farmers. Stopping work and resting to warm (χ2
(2) = 30.56, p
= 0.0001), rescheduling working hours (χ2
(2) = 7.556, p
= 0.0229), and drinking hot beverages (χ2
(2) = 75.35, p
= 0.0001) were most highly affected by the level of cold stress. All the heat- and cold-related response strategies were more significantly affected by income level (Table S8 in the Supplementary materials
This study found that individual farmers and their family members had experienced various heat-wave- and cold-spell-related illnesses and health problems between 2012 and 2017. Fatigue, dizziness, headaches, nausea, confusion, heat rashes, fainting, loss of concentration and heat strokes were the most common health problems self-reported by farming households during heat waves. Likewise, joint pain, pneumonia, respiratory problems, cold cough and indigestion were the common health issues that farmers were mostly suffered during cold spells. Though farming households had been highly affected by both forms of EWE, heat waves and cold spells, in recent years, the impact of cold spells was found to be higher on farming households. Potential reasons for this could be that there was higher acclimatisation to heat waves, and less adaptation towards cold spells, due to a limited coping capacity caused by relative poverty and farmer ignorance. Farmers were found to apply broad-brimmed hats or umbrellas, resting in the shade, slowing down their working pace, and completely stopping work during extremely hot days, rescheduling their working schedules, and applying various cooling techniques to reduce the impact of heat stress on labour productivity loss from heat waves. The main coping mechanisms used as precautionary measures to mitigate labour productivity loss during cold stress included wearing warm clothes, stopping work, resting to warm up, rescheduling working timetable, and drinking hot beverages. To help mitigate the effects of extreme weather events and save lives, public awareness campaigns should specifically target the susceptible parts of the population with information on the appropriate actions to take during extreme temperatures. Extreme temperature warnings based on weather forecasts should also be publicly broadcast, as well as heat and cold stress prevention measures. The implementation of risk communication and risk awareness through local media, providing information about the possible consequences of heat waves and cold spells, and the potential coping mechanisms, could be a primary strategy by which to mitigate potential health impacts and labour productivity losses.