(a) "Environmental geomorphology deals with the impact of natural landforms and processes." Elucidate with suitable examples. (20…

(a) Environmental geomorphology

Environmental geomorphology, as framed by D. R. Coates (1971), applies geomorphology to the interaction between landforms, geomorphic processes and human use of the environment. Its core concern is how natural landforms and processes shape habitats, resources and hazards — and how human modification of landforms feeds back on those processes.

Mechanism and Impact:

1. Erosion and Deposition: Natural processes like fluvial erosion and deposition shape the landscape. For example, the Kosi has shifted about 120 km westward over the last two centuries, and its 2008 avulsion at Kusaha reset wetlands, buried fields under sand and affected about three million people; bank erosion by the Ganga in Malda and Murshidabad similarly destroys villages and farmland.
2. Landslides and Debris Flows: In mountainous regions, steep gradients and heavy rainfall trigger landslides. Himalayan debris fans often bury agricultural terraces, leading to the loss of arable land and displacement of communities. The Wayanad (Mundakkai–Chooralmala) debris flows of 30 July 2024 and land subsidence at Joshimath (2023) show how slope processes govern the safety of settlements.
3. Coastal Processes: Coastal dune breaching and erosion can lead to the salinisation of freshwater systems. In the Sundarbans, coastal erosion and landform changes — islands such as Ghoramara have lost much of their area — threaten the fragile deltaic ecosystem and human settlements.
4. Glacial Processes: Glacial lake outburst floods (GLOFs) are a critical environmental hazard. The South Lhonak lake in Sikkim (2023) demonstrated how glacial processes can act as sudden disasters, threatening downstream infrastructure and ecosystems; it destroyed the Teesta III (Chungthang) dam.
5. Resources: Landforms also set resource potential — flood plains and alluvial fans hold productive aquifers and soils, while karst terrain controls groundwater and exposes foundations to sinkhole collapse.

Conclusion: Environmental geomorphology is essential for understanding how physical landform features dictate environmental consequences, from resource availability to natural hazard susceptibility.

(b) Consequences of AMOC collapse

The Atlantic Meridional Overturning Circulation (AMOC) is a large-scale system of ocean currents, often called the "conveyor belt," that transports warm water northward and cold water southward. Its collapse would have profound global consequences.

Consequences of Collapse:

1. Climate Cooling: A collapse would lead to significant cooling in the North Atlantic and Europe, resulting in colder winters and altered storm tracks.
2. Monsoon Shifts: The Inter-Tropical Convergence Zone (ITCZ) would shift southward. This would weaken the Sahel and Indian monsoons, leading to droughts in these regions and increased rainfall in the Southern Hemisphere.
3. Sea Level Rise: The collapse would raise sea level along the US east coast and around the North Atlantic, because a weaker Gulf Stream relaxes the sea-surface slope that it maintains across the current, adding a dynamic rise of several tens of centimetres to global sea-level rise.
4. Ecosystem Impact: North Atlantic deoxygenation and changes in temperature would disrupt marine ecosystems, affecting fish stocks and biodiversity.
5. Global Feedbacks: Through the bipolar seesaw the Southern Hemisphere would warm, tropical rainfall belts over the Amazon would shift, and North Atlantic uptake of CO₂ would weaken, amplifying warming.

Conclusion: IPCC AR6 finds the AMOC very likely to weaken this century but has medium confidence that it will not collapse abruptly before 2100, while early-warning studies (Ditlevsen and Ditlevsen, 2023; van Westen et al., 2024) suggest a tipping point may be closer. Because the system shows hysteresis, a collapse would be effectively irreversible on human timescales, making its impacts on global temperature and precipitation severe and long-lasting.

(c) Overgrazing and bioloss

Overgrazing occurs when livestock density exceeds the carrying capacity of the land, leading to bioloss (loss of biodiversity and ecosystem services).

Mechanism of Bioloss:

1. Vegetation Loss: Continuous grazing reduces phytomass (plant biomass), leading to soil exposure.
2. Soil Degradation: The loss of vegetation cover leads to the formation of a hard soil crust, reducing water infiltration and increasing erosion.
3. Woody Encroachment: In some regions, the removal of grasses leads to the dominance of woody shrubs, altering the ecosystem structure.

Regional Examples:

1. Sahel (Africa): Overgrazing has contributed to desertification, reducing the productivity of the grasslands and threatening the livelihoods of pastoralists.
2. Deccan Plateau (India): Sheep and goat grazing on commons has led to the degradation of grasslands and loss of native plant species.
3. Patagonia (South America): Overgrazing by sheep has altered the steppe vegetation, leading to soil erosion and loss of native fauna.
4. Inner Mongolia (China): Overgrazing has caused the degradation of the steppe, contributing to dust storms and loss of biodiversity.
5. Banni grasslands (Kutch, India): Heavy grazing, combined with the spread of invasive Prosopis juliflora, has shrunk the cover of palatable grasses in what was once Asia's finest tropical grassland.

Overgrazing is a major driver of bioloss, driven by socio-economic factors like sedentarisation of pastoralists. Effective management requires balancing stocking density with the land's carrying capacity to restore ecosystem health.