A scientist has now suggested that methods of mitigation of green house emissions like ocean fertilization should be reconsidered. Reducing such emissions in the first place is a much safer option than sinking them into the sea.
According to a report by ABC News, the idea has been put forward by Associate Professor Thomas Trull of the Antarctic Climate and Ecosystems Cooperative Research Center in Hobart, Australia.
AdvertisementThe comments come as the Australian Government considers its position on ocean fertilization.
"If you asked me would I do this for CO2 mitigation, I'd say not now," said Trull.
Trull said that he does not think the benefits of ocean fertilization outweigh the risks of the technology at this point, and it should only be carefully researched as an option of last resort.
"Imagine if we started to realize that we were actually headed towards melting Greenland or we were going to flood Singapore, then we might say okay, I guess we'd better do this," said Trull.
"Personally I think we should avoid that by acting now on reducing our emissions rather than hoping that these backstop technologies will save us later," he added.
Ocean fertilization involves adding nutrients such as iron or nitrogen to the sea to stimulate phytoplankton in the hope of sequestering carbon dioxide or fish stocks.
Trull said that assuming the technology works and it is possible to verify sequestration, scientific models show the maximum amount of carbon that could be sunk into the ocean is less than 15% of the world's annual human generated greenhouse emissions.
"The total capacity is about 1 Gigatonne of carbon a year," he said.
Trull said that the length of time carbon could be sequestered will vary between 6 months and 100 years.
According to Trull, no studies have been specifically designed to look at the risks of ocean fertilization, but evidence suggests possible risks include upsetting the food web and creating dead zones in the ocean.
Risks could also include producing worse greenhouse gases like nitrous oxide and methane, blocking penetration of sunlight, trapping more heat or changing ocean circulation, he added.
Trull said that using nitrogen is "more risky" than using iron, because it stays in the system for millennia, compared to iron, which sinks into sediments by natural processes over decades or a century at most.
"For me, the overall return isn't that large for something you're taking a risk on," said Trull.
"It does seem to me it's not a huge ask to reduce CO2 production by 15% by reducing the spendthrift ways in which we use energy," he added.