Mumbai: India lost around 259 billion hours of labour annually between 2001 and 2020 due to the impacts of humid heat, according to a study from researchers at Duke University. The loss of these productive hours cost India $624 billion (Rs 46 lakh crore)–equivalent to almost 7% of its 2017 gross domestic product (GDP).

The authors use the term 'humid heat' to refer to conditions that are either hot and dry or hot and humid enough to cause decreases in labor productivity.

Globally, humid heat caused 677 billion hours of lost labour each year, worth $2.1 trillion (Rs 156 lakh crore). Climate change is worsening these losses.

"Even fractions of a degree of global climate change can have large-scale implications for labour," the study said. Without rapid emissions cuts, climate change is set to further increase losses in already hot countries, and historically cooler countries will start to see more significant labour losses, according to a briefing by Climate Trends, a Delhi-based climate research firm.

In the first 20 years of this century, India lost 25 billion more hours annually compared to the previous 20 years, the paper, published in the journal Environmental Research Letters, found. "Over the last four decades, heat-related labour losses globally have increased by at least 9% (>60 billion hours annually)," the study said, as global average temperatures rose about 0.4 degrees Celsius because of human activities, per the Climate Trends briefing.

The new data also found that labour productivity can be slowed down at lower heat and humidity levels than previously assumed. The estimates are limited to workers in agriculture, fisheries, forestry and construction, the study said, adding that these sectors represent a significant proportion of the overall workforce in many regions.

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