A slowdown in the Earth’s rotation has been triggered by rising sea level across the globe says a research on the subject.
The changes in Earth’s rotation in the 20th century as linked to global sea-level rise were identified by the study that was conducted by a team led by Harvard researcher Jerry Mitrovica which published their results in Science Advances.
The large scale climatic melting of continental and oceanic ice sheets have resulted in the sea levels have been rising at unprecedented rates. The changes in Earth’s rotation, first noted by Walter Munk of Scripps Institution of Oceanography, were linked to this redistribution of water. Since the last major glaciations, several observations regarding Earth’s rotation and its rotational rate over deglaciation were noted by Munk.
Mass will redistribute around the Earth as the ice at the poles of the Earth melts, noted Munk. The Earth’s rotational speed is affected as there is a net flux of mass from the poles toward Earth’s equator as ice melts.
This redistribution of mass on Earth can be equated to the redistribution of mass as a figure skater goes from standing straight and vertical to legs and arms out to their side. His/her mass increases as the skater extends their arms outward the distance between the axis of rotation.
While conserving angular momentum, this activity of the skater increases the moment of inertia and decreases the rotational velocity. Therefore the outward the rotational velocity must slow down since the mass of ice moves from the axis of rotation that is close to the poles.
However, when observing Earth’s rotational speed and sea level rise Munk noted that there was a missing component.
The missing key was found by Mitrovica’s group - Earth’s rotating core. The researchers say that one must include Earth’s rotating core to fill in a missing component slowing down the rotational velocity when calculating relative contributions of Earth’s rotation. Scientists are able to accurately model and predict the overall Earth’s slowed rotation, with the increasing velocity of Earth’s core.
The length of one day will increase by 1.7 milliseconds in the next 100 years as measured by the scientists. However even if that time increase is very small and most would not even notice it, this small lengthening of a day has a cumulative effect when looking at thousands and millions of years.
Since 500 B.C., there has been a slowdown of approximately 4.5 hours in the Earth’s rotation and this has been determined by rotational calculations and modeling. Approximately 6,000 seconds is a result of changes in sea level from the 16,000 seconds.
The missing 10,000 seconds of time has been provided for by incorporating missing factors in the modeling of Earth’s rotation. We will see a further slowing of Earth’s rotation as ice continues to melt around the globe. It goes to show the impact melting of glacial ice has on our world although the increase in the length of a year is not significant in human timescales.
(Source:www.techtimes.com)
The changes in Earth’s rotation in the 20th century as linked to global sea-level rise were identified by the study that was conducted by a team led by Harvard researcher Jerry Mitrovica which published their results in Science Advances.
The large scale climatic melting of continental and oceanic ice sheets have resulted in the sea levels have been rising at unprecedented rates. The changes in Earth’s rotation, first noted by Walter Munk of Scripps Institution of Oceanography, were linked to this redistribution of water. Since the last major glaciations, several observations regarding Earth’s rotation and its rotational rate over deglaciation were noted by Munk.
Mass will redistribute around the Earth as the ice at the poles of the Earth melts, noted Munk. The Earth’s rotational speed is affected as there is a net flux of mass from the poles toward Earth’s equator as ice melts.
This redistribution of mass on Earth can be equated to the redistribution of mass as a figure skater goes from standing straight and vertical to legs and arms out to their side. His/her mass increases as the skater extends their arms outward the distance between the axis of rotation.
While conserving angular momentum, this activity of the skater increases the moment of inertia and decreases the rotational velocity. Therefore the outward the rotational velocity must slow down since the mass of ice moves from the axis of rotation that is close to the poles.
However, when observing Earth’s rotational speed and sea level rise Munk noted that there was a missing component.
The missing key was found by Mitrovica’s group - Earth’s rotating core. The researchers say that one must include Earth’s rotating core to fill in a missing component slowing down the rotational velocity when calculating relative contributions of Earth’s rotation. Scientists are able to accurately model and predict the overall Earth’s slowed rotation, with the increasing velocity of Earth’s core.
The length of one day will increase by 1.7 milliseconds in the next 100 years as measured by the scientists. However even if that time increase is very small and most would not even notice it, this small lengthening of a day has a cumulative effect when looking at thousands and millions of years.
Since 500 B.C., there has been a slowdown of approximately 4.5 hours in the Earth’s rotation and this has been determined by rotational calculations and modeling. Approximately 6,000 seconds is a result of changes in sea level from the 16,000 seconds.
The missing 10,000 seconds of time has been provided for by incorporating missing factors in the modeling of Earth’s rotation. We will see a further slowing of Earth’s rotation as ice continues to melt around the globe. It goes to show the impact melting of glacial ice has on our world although the increase in the length of a year is not significant in human timescales.
(Source:www.techtimes.com)
