The International Energy Agency (IEA) said a sharp decline in nuclear power capacity would threaten climate targets and security of electricity supply if developed economies did not find a way to extend their reactors.
Nuclear power is currently the world's second-largest low-carbon power source, accounting for 10 percent of the world's total Electricity generation globally.
But nuclear reactors in the United States and Europe are now over 35 years old and many of the world's 452 reactors are on the verge of closure.
Low gas prices and tight security requirements make their operation economically inefficient.
Over the past 20 years, wind and solar power capacity has increased by 580 gigawatts in advanced economies. However, the International Energy Agency estimates that the share of clean energy sources of 36 percent of global electricity supply in 2018 was 20 years ago because of the decline in nuclear power.
To compensate for the expected decline in nuclear power in the next 20 years, investment in renewable energy sources should grow by five-fold, but that would not only be a huge cost, but would require considerable investment in electricity networks, the agency said.