Big melt is making the days last longer
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 Earth’s rotation to slow, thereby lengthening our days, new research has found.
Harvard University researchers have provided an answer to a longheld conundrum over how shrinking glaciers are affecting the rotation and axis of the planet, calculating that the duration of a day has lengthened by a millisecond over the past 100 years.
The brakes will be more sharply applied as glaciers melt at a faster rate, meaning that at least five milliseconds will be added to each day over the course of the 21st century.
The axis of the Earth will shift, too, with the North Pole set to move 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 research paper by oceanographer Walter Munk examining how the melting of glaciers had altered the Earth’s rotation and axis.
As ice from the poles melts, the shifting weight of water across the world should cause a change to the axis upon which Earth spins, and a slight wobble in its rotation. Also, the added weight of water towards the Equator will cause the planet’s rotation to slow.
The Harvard team went back to Munk’s research and applied the latest scientific understanding to it. They found that Munk had slightly overestimated the average sea level rise, and had assumed that Earth had rapidly adjusted to ice melting as the Ice Age ended.
More recent understanding of this time, however, suggests that the planet was not as spherical then as it is now, as the huge ice sheets caused the poles to flatten and the Equator to bulge.
Once the team had factored in other influences such as tides, they found that the glacier melting of the 20th century had indeed caused Earth to slow and wobble.
This slowdown is set to become more pronounced. The global average sea level rise is now over 3mm, according to the Intergovernmental Panel on Climate Change, with the volume of the world’s glaciers set to slump by between 15 and 85 percent by 2100, depending on how sharply nations reduce greenhouse gas emissions and reverse deforestation.