(a) Rise of surface temperature brings severe consequences. Elaborate the potential changes and threats associated with it in the…

The Earth's climate and surface morphology operate as an interconnected thermodynamic system, where incoming solar energy, atmospheric heat retention, and endogenic tectonic forces constantly interact.

Consequences of Global Surface Temperature Rise

Anthropogenic enhancement of the greenhouse effect alters planetary energy equilibrium, producing multi-sectoral crises. Thermal expansion of ocean water combined with the melting of continental ice sheets and mountain glaciers drives eustatic sea-level rise, threatening low-lying coastal tracts and deltaic ecosystems like the Sundarbans.

Thermodynamic intensification of the hydrological cycle amplifies extreme weather events, yielding erratic monsoonal pulses, prolonged droughts, and intense tropical cyclones. In agriculture, tropical and subtropical regions face declining crop yields due to heat stress and shifting agro-climatic zones, compromising food security across South Asia and Sub-Saharan Africa.

Ecosystem disruptions manifest in widespread coral bleaching, biodiversity loss, and phenological mismatch. Public health vulnerabilities escalate through heightened incidence of lethal heatwaves, urban heat island effects, and the poleward and altitudinal expansion of vector-borne diseases such as dengue and malaria. In fragile zones like the Indian Himalayan Region (IHR), rising temperatures destabilize slope mechanics and induce glacial lake outburst floods (GLOFs).

Short-Term Temperature Variations and Radiative Processes

Short-term temperature fluctuations operate on diurnal and seasonal scales, governed by the balance between incoming shortwave solar radiation and outgoing longwave terrestrial radiation.

Diurnal variations arise from Earth's rotation, which continuously alters the solar angle of incidence and beam concentration. Surface warming peaks not at solar noon, but in the early afternoon when incoming shortwave absorption still exceeds outgoing terrestrial emission (lag effect). Nocturnal cooling occurs through continuous longwave radiative dissipation into space. This cooling is retarded by the atmospheric greenhouse effect and cloud cover, which absorb and re-radiate infrared energy back to the surface.

Seasonal variations depend on Earth's axial tilt and revolution, dictating solar declination and photoperiod duration. These variations are locally modulated by differential specific heat capacity—land surfaces heat and cool roughly five times faster than water bodies—and variable surface albedo, where fresh snow reflects up to 85% of insolation compared to darker land surfaces.

Mountain Genesis and Structural Types

Mountain building (orogenesis) occurs through distinct tectonic and denudational mechanisms:

``` Fold Mountains (Compression) Fault-Block Mountains (Tension) / / / | Horst | / \/ \/ ______| |______ --->[ Fold Strata ]<--- <---[ Graben ]---> (Faults)

Volcanic Mountains (Magmatism) Dome/Residual (Denudation) / (Crater) _₋--__ / (Cone) / (Dome) \ ====[ || ]==== (Magma) ~~~~~[ Ancient Core ]~~~~~ ```

Fold mountains develop along convergent plate boundaries where intense horizontal compressional forces deform sedimentary and crustal strata into anticlines and synclines. Examples include the young fold Himalayas (Indian-Eurasian collision), the Alps, and the Rockies.

Fault-block mountains result from tensional or rifting forces that fracture the crust along fault lines, causing differential displacement. The central upthrown block forms a horst (block mountain) flanked by downthrown grabens (rift valleys). Examples include the Vosges, the Sierra Nevada, and the block-faulted scarp of the Western Ghats.

Volcanic mountains are constructed by the subduction of oceanic plates, magma ascent, and cumulative extrusion of lava and pyroclasts. Examples include the Andes (ocean-continent subduction) and the Cascade Range.

Dome and residual mountains arise from vertical plutonic upwarping of magma without surface eruption, or the differential erosion of ancient orogens. Examples include the Black Hills of South Dakota and the relict, denuded Aravalli Range.

Anthropogenic warming directly destabilizes mountain geomorphology: accelerated cryospheric retreat in the Himalayas and Alps degrades permafrost, triggers mass wasting, and alters downstream orographic hydrology, demanding integrated climate adaptation strategies.