Heat stress on agricultural workers exacerbates crop impacts of climate change

Abstract

The direct impacts of climate change on crop yields and human health are individually well-studied, but the interaction between the two have received little attention. Here we analyze the consequences of global warming for agricultural workers and the crops they cultivate using a global economic model (GTAP) with explicit treatment of the physiological impacts of heat stress on humans’ ability to work. Based on two metrics of heat stress and two labor functions, combined with a meta-analysis of crop yields, we provide an analysis of climate, impacts both on agricultural labor force, as well as on staple crop yields, thereby accounting for the interacting effect of climate change on both land and labor. Here we analyze the two sets of impacts on staple crops, while also expanding the labor impacts to highlight the potential importance on non-staple crops. We find, worldwide, labor and yield impacts within staple grains are equally important at +3 ∘C warming, relative to the 1986–2005 baseline. Furthermore, the widely overlooked labor impacts are dominant in two of the most vulnerable regions: sub-Saharan Africa and Southeast Asia. In those regions, heat stress with 3 ∘C global warming could reduce labor capacity in agriculture by 30%–50%, increasing food prices and requiring much higher levels of employment in the farm sector. The global welfare loss at this level of warming could reach $136 billion, with crop prices rising by 5%, relative to baseline.

Projected Changes in Socioeconomic Exposure to Heatwaves in South Asia Under Changing Climate

“…The population exposure percentage for India and Pakistan is expected to upsurge over time with more intensify of GHG emissions; however, the population exposure for Afghanistan, Sri Lanka, and Bhutan is anticipated to decrease over space and time. Recent studies also investigated the heat‐induced impacts on labor productivity using the National Institute for Occupational Safety and Health (NIOSH) standards and Hot‐haps function (de Lima et al., 2021; Orlov et al., 2021; Rana et al., 2020). The labor capacity to heat stress reduces by approximately 40% and 90% following the NIOSH standards and Hot‐haps exposure function, respectively (Orlov et al., 2019).…”

Tropical deforestation accelerates local warming and loss of safe outdoor working hours

“…9,12,13,28,29 Our results suggest warming from tropical deforestation may already impact outdoor workers through the loss of safe work hours across the tropics, and this impact will be exacerbated by future warming and possible increases in deforestation. Specifically, humid heat exposure, as measured by HI or wet bulb globe temperature (WBGT), is expected to increase as the globe warms, 46,51 which will have implications for productivity of both agricultural workers, crops, 77 and livestock, 78 as well as the intensity of heat waves and associated heat stress in the tropics and subtropics. 79 There is an urgent need to bolster the climate resilience of rural populations in tropical low-and middle-income countries whose populations are often identified as contributing the least to climate change, but are expected to bear a disproportionate burden of its negative effects.…”

Regional disparities and seasonal differences in climate risk to rice labour

“…However, most crops are seasonal, and therefore have a seasonal distribution of labour; this should be taken into account in estimates of the effect of heat stress on labour. Other studies into the effect of climate change on labour productivity, even those focussed on agricultural labour, do not take this into account [ 6 , 12 , 13 , 27 ].…”

“…In this article, we estimate the labour productivity effects of climate change for rice harvesting specifically, based on data from global climate models, weather reanalysis, and a database of rice production. Other studies have made estimates of the labour productivity effects of climate change in a more general scope [ 6 , 11 – 13 ]; we examine some of the assumptions used in these studies. We identify the distribution of labour through the year as an important assumption in relation to agricultural production.…”