March 3, 2022

Bringing blue carbon out to sea

Malcolm Kennedy

In the wake of the latest installment of the IPCC Report, we here at Whale Seeker are reminded of the serious threat climate change poses for global biodiversity  — but also of the potential our ecosystems have to help combat it.

As we discussed in our last blog, the ocean and its ecosystems represent a hugely under-tapped source of carbon sequestration. These are collectively known as blue carbon. While blue carbon technically refers to all the organic carbon sequestered at sea, the focus of advocacy and research has often been on coastal wetlands: namely mangroves, sea-grasses and salt marshes. These ecosystems are miraculous: not only do they sequester carbon in plant matter itself, but also in the soil: they create organic compounds like lignin and cellulose, which remain in the soil long after the plants die, since the wet salty environments slow decomposition. As a result, coastal wetlands sequester far more carbon per area than, for instance, terrestrial forests. When coastal wetlands areas are destroyed, not only do they stop sequestering carbon, but they actually release massive amounts of CO2, as the organic compounds that have been accumulating in their soil are then exposed to the air and decompose. By addressing the health of naturally sequestering coastal and oceanic ecosystems, we can combat climate change while also providing wider environmental and human benefits like fostering biodiversity, supporting healthy fisheries, and preventing erosion.

By contrast, the carbon sequestration activity of the open seas has received less attention, for reasons we hinted at in our last blog: namely, that these regions usually lie outside the jurisdictions of national governments, and — owing to their remoteness — are less well studied. However, the open ocean is home to one of the world’s most important sources of carbon sequestration: phytoplankton. These diverse microscopic organisms currently capture around 40% of all CO2 emissions from human activities — but like coastal wetlands, they’re not as active as they once were. One reason for this is that phytoplankton depend on whales, whose feces distribute nutrients across the water column through diving, and across the globe via migration. A report from researchers at the IMF estimated that the carbon sequestration potential of a single whale is equivalent to that of 1000 trees. If we can accelerate the recovery of global whale populations, we’ll be able to recover a natural source of carbon sequestration, as well as the integrity of marine ecosystems.

How can we expand blue carbon initiatives to tap into the enormous potential of whales, and the phytoplankton they support? Currently, most of the obstacles to re-growing whale populations come from human activity at sea. A key bottleneck in preventing these conflicts is data that’s accurate, comprehensive and real-time. For Whale Seeker, this means expanding existing monitoring efforts, as well as developing the first ever precise real-time ship-born whale-detection technology, to help marine industries avoid collisions or other disturbances to whales. Doing this will bring blue carbon from the coasts to open water, protecting and growing one of the world’s most important carbon sinks.


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