The steel industry is working on solutions. According to the Leadership Group for Industry Transition, at least 73 green steel projects are in progress. But the researchers say the technology just isn't there yet.

"These technologies still face serious technical, economic, and social challenges, and have yet to be implemented at scale," said Takuma Watari, a researcher at the National Institute for Environmental Studies in Japan and the paper's first author, in a news release. It's still unclear whether enough electricity will be available in the future to power these innovations, he said.

Better processes for recycling steel scraps into high-quality materials are needed, the researchers write. They call for partnerships between the steel industry and users in a variety of sectors. But the current system "is incompatible with a zero-emission future," they write.

Eoin Treacy's view

Electric arc furnaces rely on scrap steel and the major steel producers in developed countries have been busy securing scrap supplies over the last decade. If global steel production is to grow, then relying on scrap to provide carbon content is not going to be sufficient. That means either production new steel is going to have to become much more carbon efficient or the global sector will need to contract significantly to meet carbon emissions targets.