Statistical methods more accurately determine whether the jumps in the band core data are significant or merely noisy.
Institute of Aesthetic Physics
WASHINGTON, November 16, 2021 – Sudden changes in ice core samples and other records suggest dramatic changes in climate occurred at certain times in the past.
In Chaos, by AIP Publishing, climate scientists identify abrupt shifts in the climate record that could be caused by the climate system passing a tipping point. This occurs when self-reinforcing feedback in a system pushes it out of steady state, resulting in significant change.
Identifying these events in the Earth’s past is critical to understanding the tipping points that may be encountered this century as a warming climate destabilizes the physical systems and ecosystems of the Earth. Earth.
Researchers from CNRS (France), UCLA and Columbia University have devised a statistical method to determine whether the transition seen in climate records such as ice cores is just noise or evidence of a more significant change. This is usually done by visual inspection, a time consuming and subjective process.
Their method is less prone to error, as it does not depend on human decisions about whether a jump is a significant transition. It allows to compare different records consistently and can identify important events that may have been missed in older studies.
An enhanced Kolmogorov-Smirnov (KS) test, a statistical technique named after its original authors, provides an alternative approach to recurrent analysis. The KS test has been successfully applied to other inherently noisy systems, such as finance and signal processing.
The method compares two samples taken before and after the potential transition point to check if they come from the same continuous distribution. Otherwise, the transition point is defined as a significant abrupt change indicating a true climate change.
“We applied our method to two paleontological records of the last climate cycle, an ice core in Greenland and a composite record of speleothem from China,” said author Witold Bagniewski.
Ice core analysis shows that the ratio of the two oxygen isotopes changes over time. This ratio depends on the local temperature at the time the ice formed, providing a measurement of the climate at that particular time.
Speleothems are mineral deposits in caves that show a similar pattern of isotope ratios that change as climate changes.
“Many of the abrupt transitions in the Greenland ice core record corresponded to a shift between a warmer climate, known as the Greenland Interstadials (GIs) and a colder climate, the Greenland Stadials (GSs).
The existence of these two climate states, GI and GS, is an example of a stable climate system in which two distinct states are both stable. The climate can change dramatically from one region to another when a tipping point is crossed.
“Our method is very effective in accurately detecting abrupt transitions in the climate record,” says Bagniewski. “Its broader application could help reconstruct the chronology of climate events on Earth.”
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The paper “Automatically detect abrupt transitions in paleontological climate records” by Witold Bagniewski, Michael Ghil and Denis-Didier Rousseau. The article will appear in Chaos on November 16, 2021 (DOI: 10.1063 / 5.0062543). After that date, it can be accessed at https://aip.scitation.org/doi/full/10.1063/5.0062543.
ABOUT THE JOURNEY
Chaos is dedicated to enhancing the understanding of non-linear phenomena in all fields of science and engineering and describing their manifestations in such a way that researchers from various fields can understand. See https://aip.scitation.org/journal/cha.
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JOURNEYS
Chaos An interdisciplinary journal of nonlinear science
DOI
ARTICLE TITLE
Automatic detection of abrupt transitions in paleontological climate records
ARTICLE PUBLICATION DATE
November 16, 2021
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