Climate change slows Earth's spin and lengthens days, say scientists

The impact of climate change may appear to be overwhelmingly negative but there is a bright spot for those who struggle to find enough time in the day: melting glaciers are causing the rotation of the Earth to slow thereby lengthening our days, according to a new study.

Harvard University researchers have provided an answer to a long-held conundrum over how shrinking glaciers are affecting the rotation and axis of the Earth, calculating that the duration of a day has lengthened by a millisecond over the past 100 years.

The brakes will be more sharply applied to the Earth’s rotation as glaciers melt at an ever faster rate, meaning that at least five milliseconds will be added to each day over the course of the 21st century.

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The axis of the Earth will shift too, with the north pole set to move position by about 1cm during this century.

The research, published in Science Advances , apparently solves a scientific puzzle known as “Munk’s enigma”, which came from a 2002 paper by oceanographer Walter Munk, examining how the melting of glaciers had altered the Earth’s rotation and axis.

As land ice from the poles melts due to rising atmospheric temperatures, the shifting weight of water across the world should cause a change to the axis upon which the Earth spins, and a slight wobble in the rotation.

Also, the added weight of water towards the equator will cause the Earth to slow, much in the way a spinning figure skater would slow if he or she reached their arms out away from their body.

Munk factored in the impact of the end of the Ice Age 5,000 years ago, when melting over the previous 15,000 years would have helped slow the Earth’s rotation. But, surprisingly, he found that even with average sea level rises of 2mm a year during the 20th century, there was no change to the Earth’s rotation or axis beyond that caused by the Ice Age ending.