The Greenland Ice Sheet (GrIS) has experienced unprecedented surface mass loss, primarily due to increased surface melting and subsequent runoff. This escalation is largely attributed to human-induced climate change, which has elevated Arctic temperatures, leading to more extensive and prolonged melting periods.

A significant factor in this process is the transformation occurring in the firn layer—the porous, compacted snow that sits below the surface. Historically, the firn has acted as a buffer, absorbing meltwater which then refreezes, preventing immediate runoff. However, recent studies indicate that excessive melting has saturated the firn’s pore space, leading to the formation of near-impermeable ice slabs. These slabs inhibit meltwater absorption, resulting in increased surface runoff even during cooler periods.

The consequences of this mass loss are profound. Accelerated melting contributes to globalosing risks to coastal communities worldwide. Additionally, the influx of freshwater into the ocean can disrupt thermohaline circulation patterns, potentially altering climate systems. Locally, the loss of ice mass affects ecosystems and can lead to further destabilization of the ice sheet, creating a feedback loop that exacerbates melting.

In summary, the significant reduction in the GrIS’s surface mass is primarily driven by increased surface melting due to climate change, compounded by changes in the firn’s capacity to absorb meltwater. This shrinkage has serious implications, including sea-level rise and potential disruptions to global climate patterns.

Factors Determining Ocean Salinity

Ocean salinity, the concentration of dissolved salts in seawater, is influenced by several factors:

• Evaporation and Precipitation: High evaporation rates, as in tropical regions, increase salinity. Conversely, regions with high precipitation, like near the equator, dilute salinity.
• River Discharge: Rivers bring freshwater and sediments, reducing salinity near coastal areas.
• Temperature: Warm waters promote evaporation, leading to higher salinity, whereas colder regions exhibit lower salinity.
• Ocean Currents: Warm currents carry saltier water, while cold currents dilute salinity.
• Ice Formation and Melting: Ice formation increases surrounding water’s salinity, while melting ice reduces it.

Spatial Distribution of Ocean Salinity

Salinity varies across the globe due to these factors:

• High Salinity Zones: Subtropical regions (20°–30° latitudes) have high evaporation and low precipitation, resulting in salinity levels of 36–37 ppt (parts per thousand).
• Low Salinity Zones: Equatorial regions receive heavy rainfall and river discharge, reducing salinity to about 34 ppt.
• Polar Regions: Melting ice lowers salinity, while ice formation during winters increases it.
• Enclosed Seas: Seas like the Red Sea and the Mediterranean show higher salinity due to limited freshwater inflow and high evaporation rates.

In summary, ocean salinity reflects a dynamic interplay of climatic, hydrological, and geological factors, influencing marine ecosystems and global circulation patterns.

Biome

A biome is a large ecological area on Earth with distinct plants, animals, and climate characteristics. Biomes are categorized based on factors like temperature, precipitation, and the types of organisms adapted to thrive there. They are vital for maintaining ecological balance and biodiversity.

Major Biomes of the World

1. Tropical Rainforest
   • Found near the equator (e.g., Amazon).
   • Warm temperatures (20–25°C) and high rainfall (>200 cm annually).
   • Dense forests with rich biodiversity, including species like jaguars and toucans.
2. Desert
   • Hot or cold; minimal rainfall (<25 cm annually).
   • Sparse vegetation like cacti and animals adapted to water scarcity (e.g., camels).
3. Savanna (Grassland)
   • Tropical/subtropical regions with seasonal rainfall.
   • Grass dominates with scattered trees, supporting animals like lions and zebras.
4. Temperate Forest
   • Moderate climate with distinct seasons.
   • Deciduous trees like oaks and rich wildlife, including deer and foxes.
5. Tundra
   • Cold, harsh winters; permafrost soil.
   • Vegetation limited to mosses and lichens, home to polar bears and arctic foxes.
6. Aquatic Biomes
   • Freshwater and marine ecosystems.
   • Rich biodiversity, from plankton to whales.

These biomes collectively regulate Earth’s climate and support life systems.

Landforms Created by Glaciers

Glaciers shape the landscape through erosion and deposition, creating distinct landforms:

Erosional Landforms

• Cirques: Bowl-shaped depressions formed at the head of a glacier due to ice scouring.
• Arêtes: Sharp ridges formed between two adjacent cirques or glacial valleys.
• Horns: Pyramid-shaped peaks created by the erosion of multiple cirques converging.
• U-shaped Valleys: Broad valleys with steep sides carved by glacier movement, contrasting with V-shaped river valleys.
• Hanging Valleys: Smaller U-shaped valleys that meet the main glacial valley at a higher level, often resulting in waterfalls.

Depositional Landforms

• Moraines: Accumulations of glacial debris (till) deposited at different positions, such as lateral, medial, or terminal moraines.
• Drumlins: Smooth, elongated hills composed of till, shaped by glacial ice movement.
• Eskers: Sinuous ridges formed by sediment deposition from subglacial meltwater streams.
• Outwash Plains: Flat areas formed by sediments deposited by glacial meltwater beyond the glacier’s terminal moraine.
• Kettle Lakes: Depressions formed by melting ice blocks buried in sediment.

Glacial landforms reveal the immense erosive and depositional power of ice, significantly altering landscapes over time.

Significance of the Basic Structure Doctrine

The Basic Structure Doctrine, established by the Supreme Court in the Kesavananda Bharati case (1973), ensures the Indian Constitution’s core principles remain inviolable. It emerged as a judicial safeguard against unlimited amendments under Article 368, preserving democracy, secularism, federalism, and the rule of law.

This doctrine maintains the balance of power between the judiciary and the legislature. While Parliament retains its authority to amend the Constitution, it cannot alter its “basic structure.” This protects foundational principles like judicial review, free elections, and fundamental rights from legislative overreach, especially during political turmoil.

Implications of the Doctrine

1. Preservation of Constitutional Integrity: Key cases like Indira Gandhi v. Raj Narain (1975) upheld democratic processes by striking down laws violating the basic structure.
2. Judiciary as a Guardian: The doctrine reinforces the judiciary’s role as the Constitution’s custodian, preventing authoritarian tendencies.
3. Checks on Legislative Power: It limits arbitrary amendments, ensuring governance adheres to constitutional principles.
4. Criticism of Judicial Overreach: Some argue this doctrine grants excessive power to the judiciary, potentially undermining parliamentary sovereignty.

In conclusion, the Basic Structure Doctrine ensures stability and adaptability in India’s democratic framework by preventing constitutional misuse, thus upholding the spirit of the Constitution.