The International Energy Agency says the premature closure of nuclear power plants and failure to build new ones could make it harder to meet global targets for cutting greenhouse gas emissions.
The Paris-based agency said Tuesday that "lack of further lifetime extensions of existing nuclear plants and new projects could result in an additional 4 billion tons of CO2 emissions."
Many environmental campaigners are opposed to the use of nuclear power because of the risks from power station accidents and the cost of safely disposing of spent nuclear fuel.
The IEA said advanced economies are expected to lose 25% of their nuclear capacity by 2025 and up to two thirds by 2040. It said a "drastic increase" in wind and solar energy would be needed to counter the shortfall.