UPSC Prelims 2025 Q33: Earth's Axis Shift, Ice Melt & Solar Storms
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?
- Both Statement II and Statement III are correct and both of them explain Statement I
- Both Statement II and Statement III are correct but only one of them explains Statement I
- Only one of the Statements II and III is correct and that explains Statement I
- Neither Statement II nor Statement III is correct
Answer: (b) Both Statement II and Statement III are correct but only one of them explains Statement I
Statement-wise explanation
- Statement-I: correct — Earth's spin axis has drifted about 10 metres over the past 120 years, roughly 10 cm a year in the 20th century, according to NASA-funded research. A study NASA highlighted in 2024 found that days have been getting longer by about 1.33 milliseconds per century since 2000. That is faster than at any time in the previous century. So both the rotation and the axis are measurably shifting.
- Statement-II: correct — Solar flares and the coronal mass ejections (CMEs) that come with them do hit Earth's upper atmosphere and magnetosphere with large amounts of energy. The flares and CMEs of 8–9 May 2024 caused the severe geomagnetic storm of 10–11 May 2024, which India's Aditya-L1 observed. That energy disturbs the ionosphere, satellites and power grids. It cannot change the planet's spin or move its axis, because it does not redistribute any of Earth's mass. So Statement II is true but does not explain Statement I.
- Statement-III: correct — Meltwater from Greenland, Antarctica and mountain glaciers flows into the oceans and spreads toward the equator, where the Earth bulges outward. Moving mass away from the axis raises Earth's moment of inertia, so the planet spins more slowly and days get longer. The same shift in mass, mainly from Greenland's ice loss, also moves the spin axis. This is the correct explanation of Statement I.
How to eliminate
Statements II and III are both well-established facts. Solar flares and CMEs dumping energy into the upper atmosphere is basic space-weather knowledge and was in the news in 2024. Ice-sheet meltwater redistributing across the oceans is also standard. Once you see both are true, the two options that say one or both statements are false drop out. You are left choosing between 'both explain' and 'only one explains'. To decide, ask what can change a spinning body's rotation or axis: only a shift in its mass, or a turning force (torque) acting on it. A skater slows down when they spread their arms because their mass moves away from the axis. Melting polar ice does the same to Earth by moving water from high latitudes to the equator. Solar storms deliver energy to thin air hundreds of kilometres up. They move none of Earth's mass and put no meaningful torque on a planet of about 6 × 10^24 kg. So only Statement III explains Statement I. Remember this from the question: shifts in rotation and axis come from changes in how mass is distributed (ice, water, groundwater, the mantle), not from energy arriving from space.
Know more
Why Earth's spin and axis change
Earth's angular momentum stays the same unless an outside torque acts on it. When mass moves farther from the axis, the moment of inertia rises and the spin slows, like a skater spreading their arms. When mass moves toward the axis, the spin speeds up.
What actually shifts rotation and the axis
| Driver | Effect | Timescale |
|---|---|---|
| Tidal friction from the Moon | Slows rotation; Moon recedes about 3.8 cm/yr | Millions of years |
| Polar ice melt (Greenland, Antarctica) | Water moves to the equator; days get longer; axis drifts | Decades |
| Groundwater pumping and reservoirs | Shifts mass; moves the axis | Decades |
| Glacial isostatic adjustment | Land rising after Ice Age loads were removed; axis drift | Thousands of years |
| Mantle convection and core–mantle coupling | Axis drift and changes in day length | Long term |
| Large earthquakes (e.g. 2004, 2011) | Tiny changes in day length | Instant |
Key figures (NASA-funded studies, 2016 and 2024)
- The spin axis drifted about 10 m over roughly 120 years.
- Day length has grown by about 1.33 ms per century since 2000.
- It could reach about 2.62 ms per century by 2100 under high-emission scenarios. At that point climate change would outpace the Moon's tidal braking as the main cause of day-length change.
What solar storms do instead Solar flares are bursts of radiation. CMEs are clouds of magnetised plasma. Together they cause geomagnetic storms: auroras at low latitudes, radio and GPS blackouts, satellite drag and grid surges. Their effects stay in the magnetosphere and ionosphere. They do not move Earth's mass, so they leave its rotation and axis alone. India watches them from Aditya-L1 at the Sun–Earth L1 point.
Exam tip: questions about rotation or axis shifts test mass redistribution. Questions about solar storms test space weather.
In the news
In July 2024, NASA-funded studies in PNAS and Nature Geoscience reported that melting ice is lengthening the day and shifting Earth's axis. The flares and CMEs of May 2024 caused a severe geomagnetic storm that Aditya-L1 observed. UPSC combined the two stories, so one true statement explains Statement I and the other does not.
NCERT Concepts to Revise
- Global warming: Warming of the lower atmosphere is what speeds up polar ice melt, the process Statement III describes.
- Causes of climate change: Separating solar causes from Earth-based causes is the skill needed to judge which statement explains Statement I.