UNITED NATIONS (AP) — Nuclear energy must be part of the equation to tackle climate change, the U.N. nuclear chief said Wednesday.

Climate-warming hydrocarbons still supply more than 80% of the world’s energy, even after the trillions of dollars spent in the green transition of the past 20 years, Rafael Grossi, director general of the International Atomic Energy Agency told the U.N. General Assembly.

Over a quarter of the electricity from nuclear power is low-carbon electricity and global carbon dioxide emissions would be considerably higher without nuclear power, Grossi said.

Carbon dioxide is released when fossil fuels such as oil, coal or natural gas are burned for power. In the atmosphere, the gas traps heat and contributes to the warming of the climate.

More than 400 nuclear reactors in over 30 countries are supplying global electricity, and Grossi said more than 50 are under construction and many countries are extending their existing nuclear programs.

But “nuclear power’s share of global electricity production decreased by about half” in the past two decades, he said.

Grossi said interest in nuclear energy is growing because it can not only de-carbonize electricity grids but can also de-carbonize other sectors including to produce sustainable heat for homes and industry as well as drinking water from desalination operations.

And in Africa, where electricity capacity is set to grow fivefold by 2050, and in Latin America, where it is forecast to double, countries are also looking at nuclear power, the IAEA chief said.

“Of the 30 or so countries that are currently either considering or embarking on the introduction of nuclear power, more than half are in the developing world, and most of these are in Africa,” Grossi said.

According to the International Energy Agency, more climate-warming carbon dioxide gas was emitted in 2022 than in any other year in records dating to 1900, a result of air travel rebounding after the COVID-19 pandemic and more cities turning to coal as a low-cost source of power.

Carbon dioxide emissions from energy production grew 0.9% to reach 36.8 gigatons in 2022, the agency reported in March.

Grossi said the growing worldwide interest in nuclear energy has led the IAEA to increase its high nuclear energy projection to 873 gigawatts in 2050.

But he cautioned that “to achieve such growth will require a better investment playing field, one that takes into consideration the full benefits of nuclear.”