Geography: February 2025 UPSC Current Affairs | Geography for UPSC CSE PDF Download

Structural Changes in Earth's Inner Core

Why in News?

A recent study published in Nature Geoscience has brought to light that the Earth's inner core is experiencing significant structural changes.

Key Takeaways

• Seismic waves analyzed from 1991 to 2024 near Antarctica's South Sandwich Islands reveal alterations in the inner core.
• Contrary to previous beliefs, the inner core is not as rigid and stable as once thought.
• The rotation of the inner core is reportedly slowing down, which may influence the duration of a day on Earth.

Additional Details

• Methodology: The research team studied seismic waves from repeating earthquakes, which provided insights into changes occurring within Earth's inner structures.
• Structural Changes in Inner Core: The findings indicate that the near-surface of the inner core is evolving, with viscous deformation resulting from interactions between the molten outer core and the solid inner core, akin to the behavior of magma under stress.
• Structure: The inner core is characterized as a hot, dense ball primarily composed of iron and nickel, remaining solid due to the immense pressure from the overlying layers of Earth.
• Depth and Size: It is located approximately 5,150 km beneath the Earth's surface, with a radius of about 1,220 km. The boundary separating the inner and outer core is known as the Lehmann Discontinuity.
• Magnetism: The inner core plays a crucial role in influencing Earth's magnetic field, while the outer core generates it through the geodynamo effect.
• Rotation: The inner core rotates slightly faster than the Earth's surface, completing an additional rotation every 1,000 years.
• Growth: The inner core grows at a rate of about 1 mm per year due to the solidification of the outer core, with growth being uneven and more pronounced around subduction zones.
• The complete solidification of the core will not occur due to slow crystallization and ongoing radioactive decay.

In conclusion, the findings of this study challenge previous assumptions about the inner core's stability and underline the dynamic processes occurring deep within the Earth. Understanding these changes is vital for comprehending Earth's geological and magnetic behaviors.

Arctic Warming

Why in News?

The temperatures at the North Pole (Arctic region) surged more than 20 degrees Celsius above the average temperature, raising concerns about the rapid warming of the region and its global implications. 

What are Key Facts About Arctic Warming? 

• About: It refers to the rapid increase in temperatures in the Arctic region (area north of 66.5° N latitude), also known as Arctic Amplification.  
• Since 1979, the Arctic has warmed four times faster than the global average. 
• Causes: A deep low pressure system over Iceland brought warm air from lower latitudes, causing an unusual temperature spike in the Arctic winter. 
• Abnormally high North-East Atlantic ocean temperatures intensified warming, with wind patterns carrying extra heat to the Arctic. 
• Reduced albedo effect  leads to absorption of more heat and raising temperatures.  
• The Arctic's weak convection currents trap heat from greenhouse gases near the surface, intensifying warming. 
• Potential Consequences: More ice melt could lead to coastal flooding and loss of land. 
• Arctic temperature shifts can disrupt jet streams (fast-moving, narrow bands of strong winds in the upper troposphere) impacting global rainfall, storms, and extreme weather. 
• Species like polar bears and seals depend on ice for survival, making them vulnerable to habitat loss.