2024 年全球单年温室气体排放创历史新高；相较 2023 年仅增加 0.8%，但趋势仍在上升，且科学界早已指出排放曲线应在 2020 年前后转为下降。持续排放使升温与海洋酸化加剧，并放大热浪、野火、洪水、干旱与风暴等灾害风险；对许多自然系统而言，压力已逼近永久性衰退甚至崩溃。

在接近《巴黎协定》所强调的 1.5°C 暖化门槛时，跨越「临界点」的风险上升：一旦越过阈值，系统可能从缓冲压力转为放大压力，且可能引发级联效应，推动其他要素接连失稳。已知的临界要素包含亚马逊雨林、格陵兰冰盖与 AMOC，但其确切触发暖化幅度仍在收敛；相较之下，热带珊瑚礁的风险更具高度确定性。

珊瑚礁支撑超过 4 亿人的生计，并连结旅游与渔业等「数百亿美元」规模的经济，同时是海岸抗风暴与侵蚀的重要天然屏障。大堡礁在 2016、2017、2020、2022、2024、2025 连续出现大规模白化，复原时间几乎被耗尽；研究估计其已有约 50% 因气候变迁而流失，生态正走向以藻类为主、低多样性的型态。2023–24 期间全球出现罕见的「全球性」白化事件（历史第 4 次、近 10 年第 2 次），而「九大行星边界」已有 6 项被突破；文章主张化石燃料排放需每年下降超过 5% 才能于 2050 达零排放，且到 2050 还需每年永久移除超过 50 亿吨 CO₂，否则珊瑚礁很可能仍将大量消失。

In 2024, global greenhouse-gas emissions hit an all-time annual high. The rise from 2023 was only 0.8%, but emissions are still increasing despite evidence that the curve should have turned downward by 2020. These accumulated gases are warming the planet, acidifying oceans, and intensifying heat waves, fires, floods, droughts, and storms. For systems like tropical coral reefs, the stress is shifting from recoverable damage toward permanent decline and collapse.

As warming nears the Paris Agreement’s 1.5°C limit, the risk of crossing climate tipping points grows. Tipping elements can flip from stabilizing the climate to amplifying stress, with thresholds that trigger irreversible change. There is also a nontrivial chance of cascades: one tipped system can push others past their thresholds, creating domino effects. While the precise tipping levels for the Amazon, Greenland Ice Sheet, and the AMOC are still being narrowed, coral reefs are portrayed as a high-certainty early loss.

Coral reefs support livelihoods for 400+ million people and underpin tourism and fisheries worth tens of billions of dollars, while protecting coasts from storms and erosion. The Great Barrier Reef has suffered mass bleaching in 2016, 2017, 2020, 2022, 2024, and 2025; a study estimates ~50% has been lost, with recovery time disappearing and ecosystems shifting toward algae-dominated states. A rare global bleaching event occurred in 2023–24 (the 4th in history, 2nd in a decade), and six of nine planetary boundaries are reported exceeded. The article argues fossil-fuel emissions must fall >5% per year to reach zero by 2050, plus permanent removal of >5 billion tons of CO₂ annually by 2050.