Dec 4, 2019 9:00 AM

We Need to Protect Antarctic ‘Blue Carbon’

As ice retreats, carbon could be trapped on the seabed for centuries, so long as certain nations can put conservation above commercialization.

A massive iceberg floating in the ocean in Antarctica

Both polar regions are losing marine ice. Ice shelves are breaking up into giant icebergs, more glaciers are retreating and at faster rates, less sea surface is freezing and for shorter periods. Simply put, the north and south poles are becoming less white and more blue. Yet the coldest parts of the planet are also producing some resistance to climate change. That is especially the case in Antarctica, where ice-sheet retreat will result in the expansion of “blue carbon” sites, expected to store up to 160 million metric tons of carbon annually on the seabed. The Southern Ocean is becoming Earth’s largest natural feedback on climate change. But this, too, is threatened.

Polar blue carbon provides an important but very complex ecosystem service that we are only just beginning to understand. As marine ice is lost in coastal waters, marine algae are blooming in higher densities, taking CO₂ from the atmosphere to do so. Some of this sinks to the seafloor and is buried, and some is eaten by animals who are buried upon death. This “blue carbon sink” has doubled in the last two decades. As the climate warms, ice in polar seas decreases, marine life is clawing back via carbon sequestration.

Forests worldwide presently convert and store more carbon dioxide, but almost all of it is released within a short time into the atmosphere through respiration, decomposition, or disturbance. In contrast, polar sea beds punch above their weight by immobilizing a part of the carbon as semi-permanent calcareous structures, making it easier to avoid microbial breakdown on death and burial. This locks carbon out of the atmosphere for millennia or longer, resulting in long-term sequestration of atmospheric carbon dioxide.

Glacial scouring of the sea-floor helps increase ecological diversity of benthic animals, which increase the accumulation of blue carbon.Photograph: Kristy Brown

However, these areas of emergent biodiversity are likely to face a range of natural and human threats. Antarctic blue carbon is developing in areas where fishing is not yet occurring. But as this carbon is sequestered over centuries, these areas may become both more biologically diverse and more accessible and endangered by human interference. As a consequence, we must take a long-term view on their protection. Current research does provide viable methods to identify, scale, and estimate blue-carbon sequestration value around sample sites, and their vulnerability to natural forces and human activity. (Follow the latest expedition to map and measure blue carbon emerging from glacier retreat: @icebergs_jcr.) Much more work needs to be conducted on Antarctic seabed blue-carbon dynamics, biological community buffering, and resilience to human activity, especially across spatial scales in different regions. Until these factors are better understood, it is essential to adopt a precautionary approach to protecting and promoting these globally important ecosystems.

Unfortunately, international governance of the area south of the Antarctic convergence creates a wicked legal problem. It’s the result of the complex history, regime dynamics, and jurisdictional framework of the international laws governing Antarctica and the Southern Ocean. In simple terms, the Antarctic Continent and its ice shelves are recognized as a “natural reserve” under international law, but the surrounding ocean is akin to a “high seas” fishery. So as ice shelves retreat, so does the natural reserve status, precisely at the time blue-carbon zones need strong legal protections. While the Southern Ocean fishery that replaces the natural reserve is managed under conservation-focused regulations, legally binding protections need to be made between Antarctic fishing states. But many have already opposed agreements on Marine Protected Areas in the Southern Oceans, areas much smaller than predicted blue-carbon sites.

Strong incentives will likely be necessary to convince the likes of China and Russia to forgo future access to the fisheries that will develop across much larger, biomass-rich blue-carbon areas. One possible source of incentive actually might come from the UN Climate Convention Regime. Since the Kyoto Protocol failed to establish a working carbon-trading market, the parties to that convention have been desperately trying to find ways to set up alternative, less prescriptive platforms for international cooperation on emissions reduction. In fact, a working non-market approach to international cooperation is the last piece of the Paris Climate Change Agreement’s rulebook to be hammered out, hopefully during this and next week’s climate negotiations in Madrid. Antarctic blue carbon seems an obvious subject for such global cooperation, especially since it is already a subject of global cooperative regulation. If fishing states agree to forgo future commercial harvesting in the Antarctic, they might be able to count the blue carbon sequestered there as part of their international obligations to reduce climate emissions. Since they’re not fishing there yet, the incentive seems especially high. Countries have time and again proved themselves much more willing to protect ecosystems that they don’t have an active commercial interest in (at least not in the foreseeable future).

The wider thematic focus of the UN Climate meeting is on the role of the oceans and cryosphere in climate change. While northern blue carbon and the impact of climate change on polar regions are to be discussed, Antarctic blue carbon is not. This is a significant oversight, given the importance of these sites to global mitigation, and the more general but no less urgent need to find a working subject matter for global non-market approaches to cooperative climate action. If the world community really wants to pursue these agenda items, we need to look south.

The authors of this op-ed are part of an international team of science, law, and policy researchers conducting ongoing work that includes Christoph Held, Marcus Haward, Jeff McGee, Camille Moreau, Bernabé Moreno, Maria Lund Paulsen, and Chester J Sands.

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