A rapid reduction in carbon emissions is clearly a priority to protect our ocean from further harm, but carbon dioxide removal techniques should also be explored in earnest to offer a faster, more scalable route. These range from nature-based solutions such as restoring or nurturing mangroves which increase alkalinity to more radical approaches like ocean iron fertilisation, a technique based on the theory that stimulating phytoplankton growth with iron increases atmospheric carbon absorption into the ocean, as part of the biological pump system. Such projects are now already underway, having been more theoretical in the past, but there is no global discussion about what techniques are acceptable and who controls implementation.
There are concerns that some projects, like blue carbon habitats, are not quick fixes and could take many years to come to fruition, while more radical, faster interventions could have unanticipated negative effects. Ocean iron fertilisation, for instance, could lead to downstream effects, such as robbing nutrients from ecosystems many miles away. Scientists have also revealed side-effects like the creation of new toxins that could alter the marine food web, for example.
The most promising interventions are those which restore ocean habitats to their natural state in which they can be highly effective carbon sinks. Moreover, ongoing human activities continue to thwart the ocean’s carbon dioxide-reducing function and should be tackled. The seafloor, for instance, sequesters huge amounts of CO2 but bottom trawling and certain fishing practices disturb this process. Our activities in the ocean are slowing down the natural sequestration process.