Rising temperatures in a warming world will cost poor countries tens of billions of dollars annually as they are less able to keep their workers cool, analysts said on Thursday.
Over the next 30 years, manual labourers in the agriculture, mining, oil and gas, and manufacturing sectors - which are the most prevalent in emerging economies - will be hardest hit by higher temperatures, said risk consultancy Verisk Maplecroft.
By examining energy infrastructure with temperature data and projected urban population growth, researchers said workers in Africa and Asia would be most affected by rising heat.
"That means workers are missing days because they suffer from heat stress, or their physical capacity to undertake physical activity is diminished because of those high temperatures," said Richard Hewston, head of the environment and climate change programme at Verisk Maplecroft.
"With lower labour capacity, productivity dips off and subsequently you have ripple effects through the sectors with the highest amount of manual labour," he told the Thomson Reuters Foundation.
This drop in productivity equates to an annual loss of $78 billion a year in South East Asia, and nearly $10 billion in West Africa, the consultancy's report said.
Rapid urbanisation in these emerging economies will also strain energy needs, and the demand for cooling - such as air-conditioning - will soar as temperatures rise resulting in frequent power outages, it said.
About 1.1 billion people in Asia, Africa and Latin America are at risk from a lack of air conditioning and refrigeration to keep them cool and to preserve food and medicines as temperatures rise, says global group Sustainable Energy for All.
"Even modest amounts of climate change will be impactful so that forces us to do something about it," Sam Fankhauser, director of the Grantham Research Institute at the London School of Economics, said of the Verisk Maplecroft study.
"We need to start thinking about how we build our buildings, shading, airflows, air-conditioning, green roofs, how we might adjust our behaviour, and how we design our cities," said Fankhauser, who was not involved in the report.
Two-thirds of the world's population will live in cities by 2050, with that boom concentrated in three countries - India, China and Nigeria - according to United Nations estimates released in May.
The World Health Organization has said heat stress, linked to climate change, is likely to cause 38,000 extra deaths a year worldwide between 2030 and 2050.
In 2015, countries signing the Paris Agreement set a goal of limiting a rise in average world surface temperatures to "well below" 2C (3.6F) above pre-industrial times, while "pursuing efforts" to limit rising temperatures to 1.5C (2.7F).