July 13, 2024

Lukmaan IAS

A Blog for IAS Examination



THE CONTEXT: Recent studies have highlighted how the melting polar ice is affecting Earth’s rotation and potentially influencing our timekeeping systems.


  • This phenomenon, driven by global warming, has significant implications for various aspects of our lives and requires careful consideration.
  • The melting of polar ice due to rising temperatures redistributes the Earth’s mass, particularly around the equator.
  • This redistribution alters the planet’s angular velocity, leading to changes in its rotation speed.
  • As a result, Earth’s rotation is slowing down, albeit marginally.
  • A study published in Nature, led by geophysicist from the Scripps Institution of Oceanography, highlights this phenomenon.
  • The research suggests that as polar ice melts, the increased mass around the equator affects Earth’s rotation speed, necessitating potential adjustments to our timekeeping systems.

Potential Timekeeping Implications:

  • The slowing of Earth’s rotation could prompt world timekeepers to consider subtracting a second from our clocks in the future.
  • This adjustment, referred to as a “negative leap second,” may be necessary by 2029, according to the study.
  • Such changes could have repercussions for various systems reliant on precise timekeeping, particularly in the realm of computer networks.
  • A professor of geophysics at the Massachusetts Institute of Technology (MIT) emphasizes the significance of the polar ice melt in altering Earth’s rotation.
  • The melted water from polar regions flows towards the equator, contributing to changes in the planet’s mass distribution and rotational dynamics.

Long-Term Perspective:

  • While the current changes in Earth’s rotation are notable, it’s essential to contextualize them within a broader temporal framework.
  • Earth’s rotation has undergone variations over millions of years, with days being shorter in the distant past.
  • Understanding these long-term trends provides valuable insights into the dynamic nature of our planet’s rotation.

Negative leap second:

  • A negative leap second is a second that is subtracted from our clocks to keep them in sync with the Earth’s rotation.
  • It is the opposite of a positive leap second, which is a one-second addition to our clocks.
  • The need for a negative leap second arises when the Earth’s rotation speeds up, causing a discrepancy with our clocks.
  • This adjustment is crucial to maintain the accuracy of Coordinated Universal Time (UTC) and ensure that our timekeeping systems remain aligned with the Earth’s rotation.

Rotation of the earth:

  • Earth rotates along its axis from west to east.
  • It takes approximately 24 hrs to complete on rotation.
  • Days and nights occur due to rotation of the earth.
  • The circle that divides the day from night on the globe is called the circle of illumination.
  • Earth rotates on a tilted axis. Earth’s rotational axis makes an angle of 23.5° with the normal i.e. it makes an angle of 66.5° with the orbital plane. Orbital plane is the plane of earth’s orbit around the Sun.

Polar regions:

  • Polar regions refer to the areas surrounding the Earth’s geographic poles, namely the North Pole and the South Pole.
  • These regions are characterized by extreme cold temperatures, unique ecosystems, and distinct geological features.
  • Geography and Climate:
    • North Pole:
      • The North Pole, located in the Arctic Ocean, is surrounded by several landmasses, including parts of Canada, Greenland, Russia, and Scandinavia.
      • The Arctic region experiences long, harsh winters with temperatures plummeting well below freezing, while summers are relatively short and cool.
      • Sea ice covers much of the Arctic Ocean, although this ice undergoes seasonal variations, with significant melting occurring during the summer months.
    • South Pole:
      • The South Pole is situated in Antarctica, which is a continent covered by a thick ice sheet. It is surrounded by the Southern Ocean.
      • Antarctica is the coldest place on Earth, with temperatures dropping as low as -80°C (-112°F) during the winter months.
      • The continent experiences long periods of darkness during the Antarctic winter and extended daylight during the summer, due to its location within the polar circle.

SOURCE: https://www.ndtv.com/science/melting-polar-ice-changing-earths-rotation-and-messing-with-time-study-5325413

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