Montero-Hidalgo Miriam, Tuya Fernando, Otero-Ferrer Francisco, Haroun Ricardo, Santos-Martín Fernando
Rey Juan Carlos University, Chemical and Environmental Technology Department, Madrid, Spain.
Biodiversity and Conservation Research Group, IU-ECOAQUA, Universidad de Las Palmas de Gran Canaria, Telde, Spain.
Sci Total Environ. 2023 May 10;872:162244. doi: 10.1016/j.scitotenv.2023.162244. Epub 2023 Feb 14.
Seagrasses store large amounts of blue carbon and mitigate climate change, but they have suffered strong regressions worldwide in recent decades. Blue carbon assessments may support their conservation. However, existing blue carbon maps are still scarce and focused on certain seagrass species, such as the iconic genus Posidonia, and intertidal and very shallow seagrasses (<10 m depth), while deep-water and opportunistic seagrasses have remained understudied. This study filled this gap by mapping and assessing blue carbon storage and sequestration by the seagrass Cymodocea nodosa in the Canarian archipelago using the local carbon storage capacity and high spatial resolution (20 m/pixel) seagrass distribution maps for the years 2000 and 2018. Particularly, we mapped and assessed the past, current and future capacity of C. nodosa to store blue carbon, according to four plausible future scenarios, and valued the economic implications of these scenarios. Our results showed that C. nodosa has suffered ca. 50 % area loss in the last two decades, and, if the current degradation rate continues, our estimations demonstrate that it could completely disappear in 2036 ("Collapse scenario"). The impact of these losses in 2050 would reach 1.43 MT of CO equivalent emitted with a cost of 126.3 million € (0.32 % of the current Canary GDP). If, however, this degradation is slow down, between 0.11 and 0.57 MT of CO equivalent would be emitted until 2050 ("Intermediate" and "Business-as-usual" scenarios, respectively), which corresponds to a social cost of 3.63 and 44.81 million €, respectively. If the current seagrass extension is maintained ("No Net Loss"), 0.75 MT of CO equivalent would be sequestered from now to 2050, which corresponds to a social cost saving of 73.59 million €. The reproducibility of our methodology across coastal ecosystems underpinned by marine vegetation provides a key tool for decision-making and conservation of these habitats.
海草储存大量蓝碳并缓解气候变化，但在最近几十年里，它们在全球范围内遭受了严重衰退。蓝碳评估可能有助于其保护。然而，现有的蓝碳地图仍然稀少，且集中于某些海草物种，如标志性的波喜荡属，以及潮间带和极浅海草（深度<10米），而深水和机会主义海草仍未得到充分研究。本研究通过利用2000年和2018年当地碳储存能力和高空间分辨率（20米/像素）的海草分布图，对加那利群岛的海草无茎丝粉藻的蓝碳储存和封存进行测绘和评估，填补了这一空白。特别是，我们根据四种合理的未来情景，绘制并评估了无茎丝粉藻过去、当前和未来储存蓝碳的能力，并评估了这些情景的经济影响。我们的结果表明，在过去二十年中，无茎丝粉藻的面积损失约50%，如果当前的退化速度继续下去，我们的估计表明它可能在2036年完全消失（“崩溃情景”）。到2050年，这些损失的影响将达到1.43公吨二氧化碳当量排放，成本为1.263亿欧元（占加那利当前国内生产总值的0.32%）。然而，如果这种退化速度减缓，到2050年将分别排放0.11至0.57公吨二氧化碳当量（分别为“中间”和“照常营业”情景），这分别相当于363万和4481万欧元的社会成本。如果维持目前的海草面积（“无净损失”），从现在到2050年将封存0.75公吨二氧化碳当量，这相当于节省7359万欧元的社会成本。我们的方法在以海洋植被为基础的沿海生态系统中的可重复性，为这些栖息地的决策和保护提供了一个关键工具。
