{"id":31584,"date":"2020-07-21T00:05:05","date_gmt":"2020-07-21T07:05:05","guid":{"rendered":"https:\/\/hakaimagazine.com\/?post_type=custom_features&p=31584"},"modified":"2023-11-02T12:15:46","modified_gmt":"2023-11-02T19:15:46","slug":"capturing-carbon-with-underwater-gardening","status":"publish","type":"custom_features","link":"https:\/\/hakaimagazine.com\/features\/capturing-carbon-with-underwater-gardening\/","title":{"rendered":"Capturing Carbon with Underwater Gardening"},"content":{"rendered":"
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This article was originally published in\u00a0Ensia, a solutions-focused nonprofit media outlet reporting on our changing planet. Read more stories like this at ensia.com<\/a>.<\/p>\n<\/div>\n

Sixty years ago, Tasmania\u2019s coastline was cushioned by a velvety forest of kelp so dense it would ensnare local fishers as they headed out in their boats. \u201cWe speak especially to the older generation of fishers, and they say, \u2018When I was your age, this bay was so thick with kelp, we actually had to cut a channel through it,\u2019\u201d says Cayne Layton, a postdoctoral research fellow at the Institute for Marine and Antarctic Studies at the University of Tasmania in Australia. \u201cNow, those bays, which are probably at the scale of 10 or 20 football fields, are completely empty of kelp. There\u2019s not a single plant left.\u201d<\/p>\n

Since the 1960s, Tasmania\u2019s once-expansive kelp forests have declined by 90 percent or more. The primary culprit is climate change: these giant algae need to be bathed in cool, nutrient-rich currents in order to thrive, yet regional warming in recent decades has extended the waters of the warmer East Australian Current into Tasmanian seas to devastating effect, wiping out kelp forests one by one. Warming waters have also boosted populations of predatory urchins, which gnaw on the rootlike holdfasts of kelp and compound the loss.<\/p>\n

Tasmania isn\u2019t the only site of destruction. Globally, kelps grow in forests along the coastlines of every continent except Antarctica; most of these are threatened by climate change, coastal development, pollution, fishing, and invasive predators. All of this matters because these ecosystems provide huge benefits: they cushion coastlines against the effect of storm surges and sea level rise; they cleanse water by absorbing excess nutrients; and they also slurp up carbon dioxide, which can help drive down ocean acidity and engineer a healthy environment for surrounding marine life. These forests\u2014which in the case of the giant kelp species that grows in Tasmania can reach heights of 40 meters\u2014also provide habitat for hundreds of marine species.<\/p>\n

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Around the world, kelps have a big impact on the environment, including a role as carbon sinks. Illustration by Ensia<\/p><\/div>\n

Having spent years studying these benefits, Layton is now trying to bring a patch of Tasmania\u2019s struggling kelp forests back to life. Every few weeks, he dives out to inspect three 12-by-12-meter plots he\u2019s created off the coast, each containing fronds of baby kelp, springing from ropes that are tethered to the ocean floor. These kelp nurseries are part of Layton\u2019s project to determine whether climate-resilient \u201csuper kelp\u201d that has been raised in a laboratory will fare better in Tasmania\u2019s changing seas. But his experiment also brings attention to the extraordinary potential of kelp to absorb carbon and help tackle climate change.<\/p>\n

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Climate-Forward Kelp<\/h2>\n

It\u2019s the capacity to draw CO2<\/sub> from the atmosphere that has added climate mitigation to kelp\u2019s list of benefits. When we talk about ways oceans can sequester carbon, the conversation typically revolves around mangroves, salt marshes, and seagrass meadows. But \u201cthe magnitude of carbon sequestered by algal forests is comparable to that of all those three habitats together,\u201d says Carlos Duarte, a professor of marine science at the King Abdullah University of Science and Technology in Saudi Arabia. \u201cAlgal forests should not be left behind. They have been hidden for much too long.\u201d<\/p>\n

There\u2019s a lot we still don\u2019t understand about how kelp stores CO2<\/sub>. But researchers are starting to build a better picture of this giant seaweed and how we might improve its capacity to help tackle climate change.<\/p>\n