Harnessing ENSO Teleconnections for Six-Month Predictability of Tropical Humid Heat Stress and Its Cascading Impacts on Labour Productivity

Abstract

Tropical humid heat stress, measured through wet-bulb temperature (TW) and Wet Bulb Globe Temperature (WBGT), represents a compound threat combining temperature and humidity effects that routinely pushes workers toward physiological limits. Unlike episodic heatwaves, humid heat operates as a persistent background condition constraining labour capacity and economic functioning across tropical economies. This study demonstrates that El Niño–Southern Oscillation (ENSO) teleconnections exert a dominant and predictable influence on tropical humid heat stress, with strong correlation indicating predictability up to six months in advance. Physics-based statistical models explain 80% of variance in tropical mean annual maximum wet-bulb temperature (TWmax), enabling seasonal forecasts that can inform adaptation planning across agriculture, construction, public health, energy, and supply chain management. The cascading impacts are substantial: fewer than 2018 baseline conditions, labour-capacity losses reached 9–11% across tropical economies, with sectoral losses approaching 17% in agriculture and construction. Indirect exposure transmitted through supply-chain linkages often exceeds direct sectoral losses, amplifying economy-wide consequences. The six-month predictability window offers an untapped opportunity for proactive adaptation, enabling anticipatory action rather than reactive crisis response. However, realizing this potential requires building institutional capacity, translating probabilistic forecasts into actionable guidance, and addressing the adaptation deficit in rapidly growing tropical populations. Harnessing ENSO teleconnections for seasonal prediction of humid heat stress represents a tangible pathway to reduce climate vulnerability, protect worker health and productivity, and build more resilient tropical economies in a warming world.