Rising temperatures caused by climate change may cost the world economy over $US2 trillion ($A2.63 trillion) in lost productivity by 2030 as hot weather makes it unbearable to work in some parts of the world, according to UN research.
It showed that in Southeast Asia alone, up to 20 per cent of annual work hours may already be lost in jobs with exposure to extreme heat with the figures set to double by 2050 as the effects of climate change deepen.
Across the globe, 43 countries will see a fall in their gross domestic product (GDP) due to reduced productivity, the majority of them in Asia including Indonesia, Malaysia, China, India and Bangladesh, Tord Kjellstrom, a director at the New Zealand-based Health and Environment International Trust, said.
Indonesia and Thailand could see their GDP reduced by six per cent in 2030, while in China GDP could be reduced by 0.8 per cent and in India by 3.2 per cent.
Kjellstrom authored one of six papers on the impact of climate change on health that were put together by the United Nations University's International Institute for Global Health in Kuala Lumpur and published in the Asia Pacific Journal of Public Health.
Kjellstrom warned that the lowest-paid workers - those in heavy labour, agricultural and manufacturing - were most at risk of exposure to extreme heat.
The other papers in the series showed around 2.1 million people worldwide died between 1980 and 2012 due to nearly 21,000 natural catastrophes such as floods, mudslides, extreme heat, drought, high winds or fires.
In Asia Pacific, 1.2 billon people have been affected by 1215 disasters - mostly floods, cyclones and landslides - since 2000.
The first three months of 2016 have broken temperature records and 2015 was the planet's warmest year since records began in the 19th century.