In 2012, a ship left Haida Gwaii and headed into the Pacific, where over 30 days it spread iron-rich dust across the surface of the ocean.
The strange project was an experiment with a technique that could save the world, or kill the seas.
There’s too much carbon dioxide in the atmosphere, because we keep burning coal, and oil, and gas. This is widely accepted to cause bad events, like rising sea levels and our forests catching fire every other year.
Can we remove the CO2 from the atmosphere? Maybe.
You might have heard of direct air capture. This process sucks CO2 out of the air, binds it chemically, and disposes of it.
But estimated costs for direct air capture range from $100 to $2,000 per ton, and seem to hover around $500 for the very best systems. We put 38 billion tons of CO2 into the atmosphere last year, so that would be pricey.
Oceanic iron fertilization (OIF) is the other key contender.
Cores from ancient sediment layers show that spikes in iron-rich dust in the atmosphere have coincided with rapid cooling periods. Why?
The ocean is full of plankton. All they need to thrive is water, sunlight, and a few key minerals, including iron. But vast areas of the ocean are iron deserts – there’s not enough of it for plankton to thrive. When iron arrives – from a dust plume off the Sahara Desert, or a ship or plane introducing it deliberately – the plankton multiply like crazy, all the while absorbing CO2 in the water and atmosphere.
Some plankton enter the food web, supercharging local fisheries. Some die and sink to the bottom of the ocean, trapping part of that accumulated carbon for hundreds or thousands of years.
Hooray! We’ve solved global warming, right?
Hold on. When oceans get a huge shot of nutrients, you can also get a harmful algal bloom, also known as red tide.
Blue-green algae strip oxygen out of the water, pump out toxins, kill off fish, shellfish, birds, and sea mammals. A red tide can create vast dead zones in the ocean that last for months or years.
We need more experiments to find out if OIF can be made effective, safe, and cheap. It might not work.
But it’s important to find out, because someone is going to try.
The best case scenario in a recent study suggested OIF could cost as little as $25 per ton of carbon. In other words, it would cost about $950 billion to eliminate a full year’s worth of carbon emissions.
Before you balk at the price tag, consider that California wildfires last year alone cost $165-250 billion in estimated damages.
Given the price versus the benefits someone is going to try out OIF, whether it’s proved out or not. It might be the Netherlands, or Bangladesh, or Florida. It might be a rogue insurance company. Eventually, the cost of not doing something outweighs the cost of a risky gamble.
But the best thing we can do is start testing and studying OIF, to see if it’s a saviour or a dead end.