UPSC Prelims 2025Question 33Geography

Consider the following statements:
Statement I: Scientific studies suggest that a shift is taking place in the Earth's rotation and axis.
Statement II: Solar flares and associated coronal mass ejections bombarded the Earth's outermost atmosphere with tremendous amount of energy.
Statement III: As the Earth's polar ice melts, the water tends to move towards the equator.
Which one of the following is correct in respect of the above statements?

Options

(a)Both Statement II and Statement III are correct and both of them explain Statement I
(b)Both Statement II and Statement III are correct but only one of them explains Statement I
(c)Only one of the Statements II and III is correct and that explains Statement I
(d)Neither Statement II nor Statement III is correct

Correct answer: c

Decision rule

Solar flares act on the ionosphere, satellites and grids, not on Earth's spin; axial shifts come from mass moving across the surface.

Explanation

Correct Answer:

(c) Only one of the Statements II and III is correct and that explains Statement I

Explanation of the Correct Answer:

Statement I is correct.
Scientific research, including data from National Aeronautics and Space Administration (NASA) and the journal Geophysical Research Letters, confirms that the Earth's axis and rotation are shifting, primarily due to mass redistribution on the planet's surface (e.g., melting glaciers, groundwater depletion).
Statement III is correct and explains Statement I.
- Melting of polar ice causes mass to move from higher latitudes toward the equator.
- This alters the distribution of Earth’s mass, impacting its moment of inertia and leading to shifts in rotational axis (polar drift) and even small changes in the length of a day.
- Thus, Statement III directly explains Statement I.
Statement II is incorrect.
- While solar flares and coronal mass ejections (CMEs) do emit massive energy and affect the ionosphere and satellites, they do not influence the Earth’s rotation or axial tilt.
- Their effects are atmospheric and electromagnetic, not geophysical in this context.

Solar flares and coronal mass ejections (CMEs) are distinct but related solar events. Flares are sudden bursts of radiation, often accompanied by CMEs, which are massive expulsions of plasma and magnetic fields from the Sun's corona. CMEs can travel outwards into interplanetary space at speeds ranging from hundreds to thousands of kilometers per second.

Why Other Options Are Incorrect:

(a) Incorrect: Statement II is not correct.
(b) Incorrect: Statement II is not correct, so this cannot hold.
(d) Incorrect: Statement III is correct.

Relevant Supplementary Information

Table: Concepts Related to Earth's Rotation Shift

Concept	Explanation
Earth's Axis Shift	Caused by redistribution of mass on Earth's surface (ice melt, groundwater)
Moment of Inertia	As mass moves toward equator, Earth's spin slows and axis shifts
Solar Flares and CMEs	Affect outer atmosphere and satellites; do not affect Earth's rotation
Polar Ice Melt	Leads to equator-ward water flow; changes Earth's mass balance

Related Facts:

According to NASA, Earth's rotational axis has shifted eastward by several centimeters per year since the 1990s due to Greenland and Antarctic ice melt.
The Earth's rotation speed has also been marginally affected by such shifts, changing the length of a day by milliseconds.
Solar flares do not change Earth's internal geophysics but can disrupt satellite communications and power grids.

Table 1: Concepts Related to Earth’s Rotation and Axis Shift

Concept	Explanation	Relevance to Question
Earth’s Rotation	The spinning of the Earth on its axis, completing one rotation approximately every 24 hours.	Affected subtly by mass redistribution.
Earth’s Axis Shift (Polar Drift)	The movement of the Earth’s rotational axis due to mass changes on the surface.	Confirmed by satellite data (e.g., GRACE).
Moment of Inertia	A property depending on mass distribution; changes can alter rotational dynamics.	Explains why ice melt can shift the axis.
Polar Ice Melt	Leads to water flowing toward the equator, redistributing Earth’s mass.	Explains Statement I
Solar Flares and CMEs	Sudden eruptions on the sun’s surface that emit charged particles.	Affect satellites and atmosphere, not rotation.
Impact of CMEs on Earth	Disrupt GPS, radio, power grids; heat the ionosphere; do not cause geophysical shifts.	Statement II is incorrect.

Table 2: Mass Redistribution and Earth’s Rotation

Cause of Redistribution	Effect on Earth’s Rotation
Polar Ice Melt	Water moves to equator → axis shifts and rotation slightly slows
Groundwater Depletion	Large-scale extraction and transport of water affects axial tilt
Tectonic Activity	Sudden large-scale mass shifts (e.g., earthquakes) can cause micro changes

Table 3: Scientific Evidence of Axis Shift

Source/Agency	Findings
NASA (GRACE satellite)	Earth's axis has shifted eastward due to glacial melt, esp. Greenland
JGR Solid Earth (2021)	Groundwater depletion and redistribution cause measurable axis drift
IERS (International Earth Rotation Service)	Monitors changes in Earth's rotation and pole positions

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