Flashback 2007: ‘Global warming’ will ‘reduce the length of a day’ – ‘Make Earth spin faster’
Global warming will make Earth spin faster
Of all the possible ways in which climate change could affect our planet, this is the most bizarre: as the oceans warm up, Earth will start rotating a wee bit faster, reducing the length of a day.
The time it takes for Earth to complete one rotation is affected by anything that changes the distribution of the planet’s mass relative to its axis of rotation.
“Think of an ice skater who is spinning,” says Felix Landerer of the Max Planck Institute for Meteorology in Hamburg, Germany. “When you stretch your arms out you slow down, and when you bring your arms closer to your body you spin faster.” Earth, it seems, will hug itself a little bit tighter because of global warming.
Landerer and his colleagues modelled the changes that would occur if the most realistic estimates made by the Intergovernmental Panel on Climate Change – a doubling of carbon dioxide levels by 2100 compared with 2000 – were to become reality. The team found that as the temperature of the oceans rises, the resulting changes in density and circulation would cause a net transfer of mass to the higher latitudes, closer to Earth’s axis of rotation. Consequently, Earth’s rotation would speed up, and by 2200 the length of a day would be reduced by 0.12 milliseconds (Geophysical Research Letters, vol 34, p L06307).
While “it is not something you will see on your watch,” says Landerer, it’s comparable to the influence of the tidal friction of the Earth-moon system, which slows our planet down by 2.3 milliseconds every 100 years.