Climate variability

Earth’s orbit affects millennial climate variability

There is ample geological evidence to show that Earth’s climate experienced millennial-scale variability superimposed on glacial-interglacial fluctuations during the Pleistocene. The magnitude of millennial climate variability has been linked to glacial cycles over the past 800 thousand years (kyr).

For the period leading up to the mid-Pleistocene transition, when global glaciations were less severe but more frequent, scientists had been unable to identify the link between abrupt climate change and glacial cycles.

Recently, however, scientists from China, the United States, the United Kingdom and Switzerland have found that the magnitude of millennial climate variability is constantly influenced by variations in the precession and obliquity of the Earth at the during the Pleistocene.

Their study was published in Geosciences of nature November 1.

The researchers compared four climate-sensitive elementary reports from two sea cores (U1308 in the North Atlantic and U1385 ​​on the Iberian margin) and two continental sedimentary records (Lake Ohrid on the Balkan Peninsula and loess from Gulang on the western Chinese loess plateau).

“We selected these four records because of their high sedimentation rates, long duration, availability of 100-year resolution proxy datasets, and the high sensitivity of elementary reports to abrupt climate change,” said the Professor SUN Youbin of the Institute of Earth Environment of the Chinese. Academy of Sciences (IECAS), the first author of the study.

By synchronizing these four proxy recordings with the Chinese caving δ18O records and events of glacial debris in the North Atlantic, researchers assessed the evolution of millennial climate variability over the 1.5 million years (Myr).

“Combining these four proxies into a new millennial climate variability stack provides a credible benchmark for further assessment of the dynamic interactions between orbital and millennial climate variability,” said Professor SUN.

The land-ocean synthesis of these four climate-sensitive proxy records not only demonstrates the persistent and pervasive nature of millennial climate variability over the past 1.5 Myr, but also highlights the different influences of ice caps and geometry. orbital on the magnitude of abrupt climatic events throughout the Pleistocene.

Prior to the Mid-Pleistocene transition, the magnitude of abrupt climate change was primarily influenced by changes in orbital parameters of obliquity and precession, while after the Mid-Pleistocene transition, the extent of global glaciation and orbital configurations had great potential to amplify the harsh climate. changes.

A modeling study published at the same time suggests that orbit-induced changes in processes at both high and low latitudes could amplify the magnitude of millennial climate variability.


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