Scientists shine new light on role of Earth's orbit in the fate of ancient ice sheets

In a new study published today in the journal Science, a team from the University of Wales has been able to show how the tilt and wobbling of the Earth has influenced the melting of ice sheets in the Northern Hemisphere over the past 2 million years or so.

The waxing and waning of massive Northern Hemisphere ice sheets is a result of changes in the geometry of Earth.

There are two aspects of the Earth that can affect the melting of ice sheets.

Obliquity is the angle of the Earth's tilt as it travels around the Sun and is the reason why we have different seasons.

Precession is how the Earth spins as it rotates. Depending on the angle of the wobble, the Northern Hemisphere can be close to the Sun and the Southern Hemisphere can be close to it.

The effects of obliquity and precession on the waxing and waning of the Northern Hemisphere ice sheets have resulted in ice age cycles lasting 100 thousand years.

The ice age cycles were almost exactly 41,000 years long before 1 million years ago, in a period known as the early Pleistocene.

Scientists have been puzzled as to why precession did not play a more important part in driving ice age cycles.

New evidence suggests that precession may have played a role during the early Pleistocene.

The results show that the Northern Hemisphere ice sheets have always been affected by more intense summers, but before 1 million years ago, these events were less devastating and did not lead to the complete collapse of the ice sheets.

Professor Stephen Barker, from the School of Earth and Environmental Sciences at the University of Wales, says that the early Pleistocene ice sheets in the northern hemisphere were smaller than their more recent counterparts. It has taken so long for us to find evidence of precession forcing.

The findings are the culmination of more than 12 years of work in the laboratory to process nearly 10,000 samples and develop a range of new analytical approaches. Thanks to this we can finally put to rest a long-standing problem in paleoclimatology and contribute to a better understanding of Earth's climate system.

If we hope to predict changes over the next century and beyond, we need to improve our understanding of Earth's climate dynamics. There is only one climate system and we need to understand it.

More information: Stephen Barker et al, Persistent influence of precession on northern ice sheet variability since the early Pleistocene, Science (2022). DOI: 10.1126/science.abm4033. www.science.org/doi/10.1126/science.abm4033 Journal information: Science Citation: Scientists shine new light on role of Earth's orbit in the fate of ancient ice sheets (2022, May 26) retrieved 26 May 2022 from https://phys.org/news/2022-05-scientists-role-earth-orbit-fate.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.