Physical work capacity begins to decline around 20°C ambient temperature & further diminishes as temperature, humidity & exposure to solar radiation increases
Photo: iStock The future of global food production and security is already under threat due to climate change and the problem is going to be compounded as temperature rise affects productivity of farmers and labourers, pushing it to as low as 40 per cent in important food-producing regions like India and Pakistan.
A new study by researchers from universities in the United States of America, United Kingdom and Australia revealed that the physical work capacity (PWC) in the average growing season could fall in some key food production regions due to heat exposure, by 2100.
Areas in southeast and South Asia, west and central Africa and northern South America were expected to see physical work capacity reduce to 70 per cent, while in Indo-Gangetic plains in Pakistan and India, this could fall to as low as 40 per cent, by the end of the century.
Agricultural workers plant, till and harvest much of the food that is produced and a reduction in their ability to do this work in the field will further affect food security, which is already threatened by reduction in crop yields due to different impacts of climate change.
The research, published in the journal Global Change Biology, estimated the potential for severe heat stress in agricultural workers driven by climate change using a recently developed metric — PWC. It is defined as "an individual’s work capacity relative to an environment without any heat stress” — under different predicted climate change scenarios. This approach generates quantitative estimates of the loss of work capacity across climate conditions, including more aspects of the weather.
Agricultural workers were already feeling the heat, with half the world’s cropland farmers estimated to be working below 86 per cent capacity in the “recent past” (1991-2010) climate conditions, the research showed.
“Agricultural workers are at heightened risk of exertional heat stress when manual outdoor work such as land preparation, planting, weeding and harvesting is required during periods of high ambient heat loads. To defend against hyperthermia, workers slow down to reduce metabolic heat production and the associated rise in body temperature,” said the research led by Gerald C Nelson, from the University of Illinois, US.
PWC begins to decline measurably around 20 degrees Celsius ambient temperature and further diminishes as temperature and humidity rise and exposure to solar radiation increases, while cooling from wind can reduce these effects.
To reduce the labour demands at the hottest times of year, there could be scope for shifting to varieties of crops with different growing periods that require less field labour or that have labour peaks in cooler parts of the year.
“However, this shift depends on alternate cultivar or crop availability and profitability of the alternatives. The type of shift depends on the important climate conditions locally. Temperature is important in temperate regions. In the tropics, cropping seasons are often determined by the rainy season period,” it said.
We are a voice to you; you have been a support to us. Together we build journalism that is independent, credible and fearless. You can further help us by making a donation. This will mean a lot for our ability to bring you news, perspectives and analysis from the ground so that we can make change together.
.png)
Comments are moderated and will be published only after the site moderator’s approval. Please use a genuine email ID and provide your name. Selected comments may also be used in the ‘Letters’ section of the Down To Earth print edition.