Coral reefs are a natural habitat for many species, as well as being of high economic and touristic significance. However, they represent an extremely sensitive ecosystem with a narrow ecological limit: prolonged high temperatures can lead to bleaching, in which corals expel their symbiotic algae and eventually corals will degrade and die. This work investigates the potential threat of rising temperatures to coral reefs in Southeast Asian Seas through a case study of the UNESCO Cu Lao Cham – Hoi An Biosphere Reserve. We assessed the risk caused by both rising sea surface temperature (SST) and occurrence of more extreme El Niño events. Using outputs from a regionally-downscaled climate model, we found that by the decades 2041-2050 and 2051-2060, whether with RCP 4.5 or RCP 8.5, the environmental temperature will change beyond the coral capacity threshold. Of particular concern is RCP 8.5, where the number of weeks per decade in which SST exceeds the threshold of coral reef bleaching is up to 55, compared to 0 at the beginning of the century. As well, the El Niño phenomenon often heats up waters to abnormally high temperatures in Cu Lao Cham and, using polynomial extrapolation, it is projected to rise even further. Consequently, the combination of climate change and El Niño will cause abnormal increases in the seawater environment beyond the coral resistance threshold, leading to degradation of this internationally important site.

中文翻译：

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气候变化背景下海水温度对珊瑚礁的影响。铜老湛-会安生物圈保护区的案例研究

珊瑚礁是许多物种的自然栖息地，具有很高的经济和旅游意义。然而，它们代表了一个极其敏感的生态系统，其生态极限很窄：长时间的高温会导致白化，珊瑚会排出它们的共生藻类，最终珊瑚会退化和死亡。这项工作通过对联合国教科文组织古佬湛 - 会安生物圈保护区的案例研究，调查了气温上升对东南亚海域珊瑚礁的潜在威胁。我们评估了由上升的海面温度 (SST) 和更极端厄尔尼诺事件的发生引起的风险。使用区域缩小气候模型的输出，我们发现到 2041-2050 和 2051-2060 的几十年，无论是使用 RCP 4.5 还是 RCP 8.5，环境温度将变化超过珊瑚容量阈值。特别值得关注的是 RCP 8.5，其中每十年 SST 超过珊瑚礁白化阈值的周数高达 55，而本世纪初为 0。同样，厄尔尼诺现象经常将古佬湛的水加热到异常高温，并且使用多项式外推法，预计它会进一步上升。因此，气候变化和厄尔尼诺现象的结合将导致海水环境异常增加，超过珊瑚抵抗阈值，导致这个具有国际重要性的地点退化。与本世纪初的 0 相比。同样，厄尔尼诺现象经常将古佬湛的水加热到异常高温，并且使用多项式外推法，预计它会进一步上升。因此，气候变化和厄尔尼诺现象的结合将导致海水环境异常增加，超过珊瑚抵抗阈值，导致这个具有国际重要性的地点退化。与本世纪初的 0 相比。同样，厄尔尼诺现象经常将古佬湛的水加热到异常高温，并且使用多项式外推法，预计它会进一步上升。因此，气候变化和厄尔尼诺现象的结合将导致海水环境异常增加，超过珊瑚抵抗阈值，导致这个具有国际重要性的地点退化。