Permafrost, or ground that is continuously frozen for at least 2 years, contains vast stores of organic soil carbon. Stratospheric aerosol injection (SAI) may prevent tipping points that lead to widespread permafrost thaw and carbon release by cooling surface and soil temperatures, but it is unclear if or when permafrost could stabilize after SAI deployment. Here we use output from the ARISE-SAI-1.5 simulations to assess how permafrost may respond to a specific SAI strategy that maintains global mean surface temperature to 1.5°C above pre-industrial levels. Permafrost responses under SAI are compared to responses under the control SSP2-4.5 emissions scenario. We show that the rate of boreal permafrost thaw slows under SAI but does not fully stop, likely due to deep permafrost thaw processes that are resistant to surface temperatures changes. In both the ARISE-SAI-1.5 and SSP2-4.5 simulations, permafrost completely thaws and disappears along the southern edge of the permafrost area by 2069, indicating that some permafrost loss may be inevitable even if SAI successfully stabilizes global mean surface temperatures. SAI does prevent a potential local tipping point (talik formation) in roughly 1 million km² of permafrost. Most of the talik prevention occurs in permafrost peatlands. Thus, a more aggressive SAI strategy than that of ARISE-SAI-1.5 is likely required to prevent all future projected permafrost thaw.

中文翻译：

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ARISE-SAI-1.5 情景下平流层气溶胶注入稳定北半球陆地永久冻土层

永久冻土或连续冻结至少两年的地面含有大量的有机土壤碳。平流层气溶胶注入（SAI）可能会通过冷却地表和土壤温度来防止导致大面积永久冻土融化和碳释放的临界点，但尚不清楚在SAI部署后永久冻土是否或何时能够稳定。在这里，我们使用 ARISE-SAI-1.5 模拟的输出来评估永久冻土如何响应特定的 SAI 策略，该策略将全球平均表面温度维持在比工业化前水平高 1.5°C 的范围内。将 SAI 下的永久冻土响应与控制 SSP2-4.5 排放情景下的响应进行比较。我们发现，在 SAI 影响下，北方永久冻土融化速度减慢，但并未完全停止，这可能是由于深层永久冻土融化过程对地表温度变化具有抵抗力。在 ARISE-SAI-1.5 和 SSP2-4.5 模拟中，到 2069 年，永久冻土将在永久冻土区南缘完全融化并消失，这表明即使 SAI 成功稳定了全球平均地表温度，一些永久冻土损失也可能是不可避免的。 SAI 确实防止了大约 100 万平方公里^永久冻土层中潜在的局部临界点（talik 地层）。大多数塔利克预防工作发生在永久冻土泥炭地。因此，可能需要比 ARISE-SAI-1.5 更积极的 SAI 策略来防止未来所有预计的永久冻土融化。