College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4PS, UK.
Philos Trans A Math Phys Eng Sci. 2012 Mar 13;370(1962):1185-204. doi: 10.1098/rsta.2011.0304.
We address whether robust early warning signals can, in principle, be provided before a climate tipping point is reached, focusing on methods that seek to detect critical slowing down as a precursor of bifurcation. As a test bed, six previously analysed datasets are reconsidered, three palaeoclimate records approaching abrupt transitions at the end of the last ice age and three models of varying complexity forced through a collapse of the Atlantic thermohaline circulation. Approaches based on examining the lag-1 autocorrelation function or on detrended fluctuation analysis are applied together and compared. The effects of aggregating the data, detrending method, sliding window length and filtering bandwidth are examined. Robust indicators of critical slowing down are found prior to the abrupt warming event at the end of the Younger Dryas, but the indicators are less clear prior to the Bølling-Allerød warming, or glacial termination in Antarctica. Early warnings of thermohaline circulation collapse can be masked by inter-annual variability driven by atmospheric dynamics. However, rapidly decaying modes can be successfully filtered out by using a long bandwidth or by aggregating data. The two methods have complementary strengths and weaknesses and we recommend applying them together to improve the robustness of early warnings.
我们研究了在达到气候临界点之前是否可以提供稳健的早期预警信号，重点关注试图检测关键减速作为分叉前兆的方法。作为一个测试平台，重新考虑了六个之前分析过的数据集，其中三个古气候记录在末次冰期结束时接近突然转变，三个模型的复杂程度不同，通过大西洋热盐环流崩溃而被迫进行。同时应用并比较了基于检查滞后 1 自相关函数或去趋势波动分析的方法。检查了数据聚合、去趋势方法、滑动窗口长度和滤波带宽的影响。在 Younger Dryas 末期突然变暖事件之前发现了稳健的临界减速指标，但在 Bolling-Allerød 变暖或南极洲冰川结束之前，这些指标不太明显。由大气动力学驱动的年际变异性可能掩盖了热盐环流崩溃的早期预警。然而，通过使用长带宽或聚合数据可以成功地过滤掉快速衰减模式。这两种方法各有优缺点，我们建议将它们结合使用以提高早期预警的稳健性。
