Diminishing prospects for environmental preservation under climate change are intensifying efforts to boost capture, storage and sequestration (long-term burial) of carbon. However, as Earth’s biological carbon sinks also shrink, remediation has become a key part of the narrative for terrestrial ecosystems. In contrast, blue carbon on polar continental shelves have stronger pathways to sequestration and have increased with climate-forced marine ice losses—becoming the largest known natural negative feedback on climate change. Here we explore the size and complex dynamics of blue carbon gains with spatiotemporal changes in sea ice (60–100 MtCyear⁻¹), ice shelves (4–40 MtCyear⁻¹ = giant iceberg generation) and glacier retreat (< 1 MtCyear⁻¹). Estimates suggest that, amongst these, reduced duration of seasonal sea ice is most important. Decreasing sea ice extent drives longer (not necessarily larger biomass) smaller cell-sized phytoplankton blooms, increasing growth of many primary consumers and benthic carbon storage—where sequestration chances are maximal. However, sea ice losses also create positive feedbacks in shallow waters through increased iceberg movement and scouring of benthos. Unlike loss of sea ice, which enhances existing sinks, ice shelf losses generate brand new carbon sinks both where giant icebergs were, and in their wake. These also generate small positive feedbacks from scouring, minimised by repeat scouring at biodiversity hotspots. Blue carbon change from glacier retreat has been least well quantified, and although emerging fjords are small areas, they have high storage-sequestration conversion efficiencies, whilst blue carbon in polar waters faces many diverse and complex stressors. The identity of these are known (e.g. fishing, warming, ocean acidification, non-indigenous species and plastic pollution) but not their magnitude of impact. In order to mediate multiple stressors, research should focus on wider verification of blue carbon gains, projecting future change, and the broader environmental and economic benefits to safeguard blue carbon ecosystems through law.

气候变化下环境保护前景的减弱正在加大力度促进碳的捕获、储存和封存（长期埋藏）。然而，随着地球的生物碳汇也在缩小，修复已成为陆地生态系统叙述的关键部分。相比之下，极地大陆架上的蓝碳具有更强的封存途径，并且随着气候导致的海冰损失而增加——成为已知的最大的气候变化自然负反馈。在这里，我们探讨了随着海冰（60-100 MtCyear ^-1）、冰架（4-40 MtCyear ^-1  = 巨大的冰山生成）和冰川退缩（< 1 MtCyear ^-1）。估计表明，其中最重要的是减少季节性海冰的持续时间。海冰范围的减少会推动更长的（不一定是更大的生物量）更小细胞大小的浮游植物大量繁殖，增加许多初级消费者的增长和底栖碳储存——其中封存机会最大。然而，海冰损失也会通过增加冰山运动和底栖生物冲刷在浅水区产生正反馈。与增加现有汇的海冰损失不同，冰架损失会在巨型冰山所在的地方和它们的尾迹处产生全新的碳汇。这些也会从冲刷中产生小的积极反馈，通过在生物多样性热点重复冲刷来最小化。冰川退缩造成的蓝碳变化量化得最差，尽管新兴峡湾面积很小，它们具有很高的储存-隔离转换效率，而极地水域中的蓝碳面临着许多多样化和复杂的压力源。这些的特性是已知的（例如捕鱼、变暖、海洋酸化、非本土物种和塑料污染），但它们的影响程度尚不清楚。为了调解多重压力，研究应侧重于更广泛地验证蓝碳收益、预测未来变化以及更广泛的环境和经济效益，以通过法律保护蓝碳生态系统。