The article explores the concept of "critical slowing down" as an early warning signal for abrupt climate change. The authors analyze eight ancient abrupt climate shifts and find that all of them were preceded by a characteristic slowing down of fluctuations, measured as increased autocorrelation. This slowing down is a hallmark of tipping points, suggesting that past abrupt shifts were associated with the passing of critical thresholds. The authors argue that this method of detecting slowing down could be used as a universal early warning signal for upcoming catastrophic changes in complex systems, including the climate system. They also discuss the robustness of their findings to different data processing methods and compare them with model results, further supporting the idea that critical slowing down is a reliable indicator of approaching tipping points.The article explores the concept of "critical slowing down" as an early warning signal for abrupt climate change. The authors analyze eight ancient abrupt climate shifts and find that all of them were preceded by a characteristic slowing down of fluctuations, measured as increased autocorrelation. This slowing down is a hallmark of tipping points, suggesting that past abrupt shifts were associated with the passing of critical thresholds. The authors argue that this method of detecting slowing down could be used as a universal early warning signal for upcoming catastrophic changes in complex systems, including the climate system. They also discuss the robustness of their findings to different data processing methods and compare them with model results, further supporting the idea that critical slowing down is a reliable indicator of approaching tipping points.