麻豆传媒

A former UK chief scientific adviser is planning experiments to drop sand naturally containing iron in oceans to tackle climate change and restore marine life, in a major geoengineering project that is likely to prove controversial.

Ships will be sent to three locations across the world鈥檚 oceans in the next four years to trial the technique 鈥� known as ocean iron fertilisation 鈥� David King at the at Cambridge (CCRC), UK, tells 麻豆传媒.

The plan is to emulate and accelerate natural processes, such as the way wind transports dust from the Sahara desert and deposits iron in the Atlantic Ocean. The iron fertilises the growth of phytoplankton, which absorbs CO2 from the air, eventually locking it away in the ocean.

King, a former UK chief scientific adviser who earlier this month, says the technique can also help 鈥渞estock the oceans with fish and animals鈥� 鈥� including ultimately helping whale populations 鈥� because of the phytoplankton bloom. 鈥淚t has the greatest promise and the least amount of effort being put into [it] at the moment鈥� of all CO2 removal approaches, says King.

Studies have shown that iron fertilisation can work, but past real-world trials have proven controversial and been accused of violating international rules. King describes his planned experiments, coordinated by the CCRC, as a 鈥渂ig international effort鈥� to explore the approach.

鈥淚f the programme works, it鈥檚 quite possible with just this one technique that we could be taking up 10 to 30 billion tonnes of greenhouse gases a year,鈥� says King. 鈥淲e鈥檇 have to be covering 2 to 3 per cent of the world鈥檚 deep ocean surface with small particles containing iron in order to achieve that. And we are keen to see if we can do that. It鈥檒l be very cheap because iron is very cheap.鈥�

Wil Burns at American University in Washington DC says the scheme may have to clear international governance hurdles to go ahead. A global agreement known as the , which covers the dumping of waste and other materials at sea, would be relevant, he says. It allows for small-scale and research-focused projects, but it is unclear whether this latest plan would be approved.

The scheme may also have to engage with criteria set by the United Nations Convention on Biological Diversity and the UN Convention on the Law of the Sea, says Burns.

Whether further experiments on ocean iron fertilisation are needed has also been called into question by other researchers. by Rob Bellamy at the University of Manchester in the UK and his colleagues, published in February, concluded that 鈥渨e might reasonably question whether further research is necessary in order to rule this out as an option鈥�.

The technology isn鈥檛 at a credible stage, says Bellamy. 鈥淭here have been quite a few experiments already, but huge uncertainties remain over how much CO2 is captured, and how long it stays down at the bottom of the ocean. The latest best estimates put its potential at a measly 1 to 3 billion tonnes of CO2 removed per annum.鈥� Burns also thinks that King鈥檚 CO2 removal estimates are too high, calling them 鈥減ie in the sky鈥�.

One of the main stumbling blocks could be public attitudes, as , says Bellamy. 鈥淧eople don鈥檛 like it.鈥�

Ocean iron fertilisation is ranked even lower than putting aerosols in the atmosphere to manage the amount of the sun鈥檚 energy reaching Earth, he says. Such solar radiation management experiments have received strong pushback, with one effort that was due to go ahead in Sweden being recently postponed for a year.

King says he is aware of the sensitivities around putting iron in the oceans to fight climate change. 鈥淭hat鈥檚 why we are stressing that this is a question of returning the oceans to their biological state and, by the way, we take greenhouse gases out of the atmosphere. If the experiments work, which will take at least 4 years, we鈥檝e got to do a very detailed analysis to show no negative impact.鈥� The team have already begun research on public attitudes, he says.

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