Environmental Research Letters<\/em>, have wide-ranging implications for scientists\u2019 understanding of the planet\u2019s carbon balance. Typically, scientists think seagrass meadows are responsible for 18 percent of the ocean\u2019s carbon storage. Johannessen says those estimates could be 10, or even as much as 3,000 times, too high.<\/p>\nJohannessen\u2019s findings have been met with resistance from the blue carbon research community. Yet if she\u2019s right, they could cause an important recalculation of marine carbon cycling.<\/p>\n
More than that, Johannessen\u2019s findings could shake up the burgeoning carbon offset industry. Greenhouse gas markets base the sales of carbon credits from seagrass bed restoration projects on estimates of how much carbon they store. If seagrass stores less carbon than thought, the value of these seagrass beds plummets. Similarly, if carbon credits are awarded on the basis of overblown estimates, the net effect could be an unintended increase in the amount of carbon dioxide being released into the atmosphere.<\/p>\n
So how, according to Johannessen, did blue carbon researchers get their estimates so wrong?<\/p>\n
Johannessen says it all comes down to bad math. Blue carbon researchers, she says, misunderstand how marine sediments receive, process, and store organic carbon.<\/p>\n
\u201cThe authors of all the previous blue carbon papers have expertise in seagrass biology or terrestrial carbon burial, but they do not understand how marine sediments work,\u201d she says.<\/p>\n
In particular, she says the rate at which sediment builds up in seagrass beds has been overestimated, as have the concentrations of carbon within the sediments. And carbon storage estimates are made by multiplying those two factors.<\/p>\n
Some blue carbon researchers, however, believe Johannessen is wrong. Yesterday, a group of scientists from Deakin University in Australia fired back, publishing a response in Environmental Research Letters <\/em>criticizing her methods and conclusions. They insist that previously published carbon storage rates are indeed correct.<\/p>\n\u201cJohannessen\u2019s paper misreported, miscalculated, and cherry-picked what they reported,\u201d says Peter Macreadie, head of Deakin\u2019s Blue Carbon Lab and lead author of the response.<\/p>\n
\u201cThe blue carbon world is aware of the limitations and scientific challenges ahead when it comes to measuring carbon dioxide abatement, but it\u2019s unhelpful to have tire kickers who aren\u2019t prepared to be part of the solution,\u201d Macreadie says.<\/p>\n
Johannessen says she\u2019s only trying to help. In the past, when she has come across inaccurate storage estimates in international protocol documents, she made a point of reaching out to the authors, offering to explain how they could improve their methods and calculations. No one, she says, has taken her up on the offer.<\/p>\n
Johannessen has ruffled some feathers with her bold claim, but she\u2019s not alone in her assertion that blue carbon researchers have got their math wrong. Thomas Bianchi, a professor of geology at the University of Florida, says he understands her stance. Without an accurate representation of how carbon moves through marine sediments over time, he says, scientists have only snapshots of the current carbon storage.<\/p>\n
The two camps are arguing over more than mud. The stakes\u2014an accurate assessment of global carbon stores\u2014are high. But Johannessen says there\u2019s still time to make things right.<\/p>\n
\u201cThere is nothing to be done about the scientific papers that are already published,\u201d she says. \u201cBut it\u2019s not the end of the world for the field.\u201d<\/p>\n
\u201cThis is how science advances,\u201d she adds.<\/p>\n","protected":false},"excerpt":{"rendered":"
Seagrass meadows take up less than 0.1 percent of the world\u2019s oceans; nevertheless, they are considered a huge carbon sink. Seagrass draws carbon dioxide out of the atmosphere, using it to fuel its own growth through photosynthesis. When the seagrass <\/p>\n
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