[Rockhounds] New study solves long-standing mystery of what may have triggered ice age

[Kreigh Tomaszewski]

A new study led by University of Arizona researchers may have solved two
mysteries that have long puzzled paleo-climate experts: Where did the ice
sheets that rang in the last ice age more than 100,000 years ago come from,
and how could they grow so quickly?

Understanding what drives Earth's glacial–interglacial cycles—the periodic
advance and retreat of ice sheets in the Northern Hemisphere—is no easy
feat, and researchers have devoted substantial effort to explaining the
expansion and shrinking of large ice masses over thousands of years. The
new study, published in the journal *Nature Geoscience*, proposes an
explanation for the rapid expansion of the ice sheets that covered much of
the Northern Hemisphere during the most recent ice age, and the findings
could also apply to other glacial periods
<https://phys.org/tags/glacial+periods/> throughout Earth's history.

About 100,000 years ago, when mammoths roamed the Earth, the Northern
Hemisphere climate plummeted into a deep freeze that allowed massive ice
sheets to form. Over a period of about 10,000 years, local mountain
glaciers grew and formed large ice sheets covering much of today's Canada,
Siberia and northern Europe.

While it has been widely accepted that periodic "wobbling" in the Earth's
orbit around the sun triggered cooling in the Northern Hemisphere summer
that caused the onset of widespread glaciation, scientists have struggled
to explain the extensive ice sheets covering much of Scandinavia and
northern Europe, where temperatures are much more mild.

https://phys.org/news/2022-06-long-standing-mystery-triggered-ice-age.html