Washington

An international consortium is withdrawing its application for a permit to conduct a large carbon-sequestration experiment off the coast of Hawaii, in the face of opposition from environmentalists.

The researchers, who plan to release tonnes of liquefied carbon dioxide in the deep ocean, say there are no environmental grounds for dropping the $5 million project. They plan to decamp to Norway, and expect to find out in the next few weeks whether they have permission to do the work there.

Results from the experiment are expected to shed light on the feasibility of carbon sequestration in the oceans as a means of mitigating the build-up of carbon dioxide in the atmosphere, which most researchers think causes global warming.

The time taken to secure a permit “was becoming excessive”, says Gerard Nihous, an ocean engineer at the Pacific International Center for High Technology Research in Honolulu, which was due to carry out the study. He says the consortium plans to notify the US Environmental Protection Agency (EPA) this week that it is withdrawing its permit application.

The amount of carbon dioxide to be released in Norway will be less than the 60 tonnes envisaged for release in Hawaii, but it will still be the largest experiment of its type, the researchers say.

The project, which is supported by Japan, the United States and Norway, was conceived in the 1997 meetings that led to the Kyoto Protocol. But local environmental groups claimed that the experiment would acidify Hawaii's fishing grounds (see Nature 401, 315; 199910.1038/43745).

Environmentalists are suspicious of the experiment because they see carbon sequestration as a 'red herring' introduced into the Kyoto negotiations to divert attention from the need to reduce greenhouse-gas emissions. “We're against the study because we think it's part of a larger effort that is looking for a panacea that will encourage more fossil-fuel use,” says Jeffrey Mikulina, director of the Hawaiian chapter of the Sierra Club, a large US environmental group.

But an assessment performed for the EPA said that the experiment would have no substantial environmental impact. “If we halt small experiments like this, we're never going to get the answers,” says Howard Herzog of the Massachusetts Institute of Technology, one of the study's investigators.