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‘True Polar Wander’ and Earth’s Ice Ages

Rice University geophysicists have determined Earth shifted relative to its spin axis within the past 12 million years, which caused Greenland to move far enough toward the north pole to kick off the ice age that began about 3.2 million years ago.

The study is based on an analysis of fossil signatures from deep ocean sediments, the magnetic signature of oceanic crust and the position of the mantle “hot spot” that created the Hawaiian Islands.

Co-authors Richard Gordon and Daniel Woodworth said the evidence suggests Earth spun steadily for millions of years before shifting relative to its spin axis, causing the geographic locations of the north and south poles to change, or “wander.”

Geophysicists refer to this effect as “true polar wander.”

True polar wander occurs when the entire Earth shifts relative to its spin axis. Credit: Victor C. Tsai/Wikimedia Commons

“We’re taking these hot spots as marked trackers of plumes that come from the deep mantle, and we’re using that as our reference frame,” Gordon said.

“We think the whole global network of hotspots was fixed, relative to the Earth’s spin axis, for at least 36 million years before this shift.”

“It was only about a 3 degree shift, but it had the effect of taking the mantle under the tropical Pacific and moving it to the south, and at the same time, it was shifting Greenland and parts of Europe and North America to the north. That may have triggered what we call the ice age,” Gordon said.

Earth is still in an ice age that began about 3.2 million years ago, authors say.

Earth’s poles have been covered with ice throughout the age, and thick ice sheets periodically grow and recede from poles in cycles that have occurred more than 100 times.

During these glacial cycles, ice has extended as far south as New York and Yellowstone National Park. Earth today is in an interglacial period in which ice has receded toward the poles.

For the full article from, click here.

Our current interglacial period has all but run its course.

The cold times are returning.


Grand Solar Minimum


{Feature Image: NASA]

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One Thought to “‘True Polar Wander’ and Earth’s Ice Ages”

  1. Ian MacCulloch

    The oldest known ‘blue’ ice is 3.2 million years old so development of the current bases= climate is OK for Antarctica but delayed until 432,000 years ago in Greenland/Arctic.
    A good bit of work though and if the two two geophysicists can reconcile the difference between the north and the south that will be huge.

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