Researchers have developed an automated method for the detection and precise dating of abrupt climate events in paleoclimatic data. The results will facilitate the study of climate tipping in the past. The work by Witold Bagniewski, École Normale Supérieure, Paris, France and colleagues was published today in the journal Chaos. The study is part of the TiPES-project, an international scientific collaboration between 18 European universities and private partners on tipping points in the Earth system.
Traces of tipping
Paleoclimate records document abrupt climate transitions in abundance. The traces of these quick climatic changes in the past are found in diverse sources, including marine sediments, loess deposits, ice-cores from Greenland and Antarctica, speleothems, as well as lake sediments. The findings, in addition to theoretical insights, have raised the concern that we risk tipping points in the current and future climate system as well. If such tipping points are crossed due to global warming, the climate system will shift abruptly and irreversibly to a warmer regime.
Abrupt transitions through climate tipping are therefore intensively studied in climate science.
Paleo-data however, are usually very different in nature, as they vary in time-resolution, types of climate signals and geographical distribution. This presents a challenge in the study of climate tipping. Therefore, improved dating and detection of past abrupt transitions might help in that regard.
Quick and objective
Now, Witold Bagniewski, together with Michael Ghil and Denis-Didier Rousseau has developed a method to identify abrupt climate events in paleoclimatic records. The statistical tool has been thoroughly tested on well-known and intensively studied data. Essentially a modified Kolmogorov-Smirnov test, the method offers a number of possibilities that potentially can improve comparisons of climate records and thus facilitate the study of climate tipping.
First of all, the new method is quick and objective. Apart from that, it can be tuned to find events of a variety of amplitudes. Most importantly though, is the automated process's potential for estimating precise dates for transitions.
Precise dating of onsets of abrupt transitions could help establish the chronology of close events. It will also be useful in eliminating uncertainties during the comparison of different paleo records.
Works on different timescales
"Finally, we can use the method to focus on different timescales. Like glacial cycles of tens of thousands of years vs. Dansgaard-Oeschger events (abrupt warmings during the last ice age) which would be on a thousand-year time scale. Or we can focus on even shorter events, too. In the paper, we try to have all of them together," explains Witold Bagniewski.
The algorithm was tested on datasets from Chinese speleothems and ice-cores from the ice sheet of Greenland.
"Next we want to try data from other ice cores, speleothems, and marine sediments. But also different forms of proxy data, like pollen records from lake sediments, loess records from landmasses, and so on," says Bagniewski.
The TiPES project is an EU Horizon 2020 interdisciplinary climate science project on tipping points in the Earth system. 18 partner institutions work together in more than 10 countries. TiPES is coordinated and led by The Niels Bohr Institute at the University of Copenhagen, Denmark and the Potsdam Institute for Climate Impact Research, Germany. The TiPES project has received funding from the European Horizon 2020 research and innovation program, grant agreement number 820970.
