Tipping elements are components of the Earth system which may respond nonlinearly to anthropogenic climate change by transitioning toward substantially different long-term states upon passing key thresholds or “tipping points.” In some cases, such changes could produce additional greenhouse gas emissions or radiative forcing that could compound global warming. Improved understanding of tipping elements is important for predicting future climate risks and their impacts. Here we review mechanisms, predictions, impacts, and knowledge gaps associated with 10 notable Earth system components proposed to be tipping elements. We evaluate which tipping elements are approaching critical thresholds and whether shifts may manifest rapidly or over longer timescales. Some tipping elements have a higher risk of crossing tipping points under middle-of-the-road emissions pathways and will possibly affect major ecosystems, climate patterns, and/or carbon cycling within the 21st century. However, literature assessing different emissions scenarios indicates a strong potential to reduce impacts associated with many tipping elements through climate change mitigation. The studies synthesized in our review suggest most tipping elements do not possess the potential for abrupt future change within years, and some proposed tipping elements may not exhibit tipping behavior, rather responding more predictably and directly to the magnitude of forcing. Nevertheless, uncertainties remain associated with many tipping elements, highlighting an acute need for further research and modeling to better constrain risks.

中文翻译：

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地球系统倾翻要素的机制和影响

引爆因素是地球系统的组成部分，它可能通过在超过关键阈值或“引爆点”时向截然不同的长期状态转变来非线性地响应人为气候变化。在某些情况下，此类变化可能会产生额外的温室气体排放或辐射强迫，从而加剧全球变暖。更好地了解引爆因素对于预测未来气候风险及其影响非常重要。在这里，我们回顾了与被提议作为引爆因素的 10 个著名地球系统组成部分相关的机制、预测、影响和知识差距。我们评估哪些引爆因素正在接近临界阈值，以及转变是否会迅速显现或在更长的时间尺度内显现。一些引爆因素在中间排放路径下具有更高的跨越引爆点的风险，并可能影响 21 世纪的主要生态系统、气候模式和/或碳循环。然而，评估不同排放情景的文献表明，通过减缓气候变化，减少与许多引爆因素相关的影响的潜力很大。我们审查中综合的研究表明，大多数引爆因素不具备未来几年内突然变化的可能性，一些拟议的引爆因素可能不会表现出引爆行为，而是更可预测和直接地响应强迫的大小。然而，不确定性仍然与许多引爆因素相关，突出表明迫切需要进一步研究和建模以更好地限制风险。