AMOC, ITCZ, and Climate Change

• These notes cover 27 months of Science & Technology current events, from June 1, 2023, to the Mains 2025 exam.
• The information comes from newspapers, websites, and magazines.
• Current affairs from the last 4-5 years are included.
• NCERT books, standard textbooks, newspapers, websites, and the internet were consulted.

Atlantic Meridional Overturning Circulation (AMOC) and Inter-tropical Convergence Zone (ITCZ)

• Research suggests global warming is weakening the Atlantic Meridional Overturning Circulation (AMOC).
• A weakened AMOC could shift the Inter-tropical Convergence Zone (ITCZ) southward.
• The ITCZ shift may disrupt global climate patterns, including the Indian monsoon.
• The Atlantic Meridional Overturning Circulation is a major component of Earth’s climate system.
• It involves a large-scale movement of warm, salty water in the Atlantic Ocean's upper layers, moving north.
• The AMOC also involves cold, deeper waters moving south.
• Water density results from temperature and salinity gradients, affecting the AMOC.
• The AMOC regulates climate by distributing heat, influencing weather patterns, and affecting land masses, such as in Europe and North America.
• The Inter-tropical Convergence Zone is a low-pressure belt near Earth's equator.
• Trade winds from the Northern and Southern Hemispheres converge.
• The Inter-tropical Convergence Zone features cloudiness and precipitation due to solar heating.
• The ITCZ influences tropical rain belts and storm patterns and shifts seasonally, affecting climatic conditions.
• A study by researchers on the Atlantic Meridional Overturning Circulation (AMOC) showed its influence on the Indian monsoon.
• The AMOC moves warm tropical water northward and cold water southward, to distribute heat around the globe, regulating climate patterns.
• The study found that mixing Atlantic and Arctic waters affect the AMOC.
• 72% of the AMOC's lower limb consists of Atlantic waters, and 28% is Arctic waters, which is crucial for function and strength.
• Global warming could weaken the AMOC, reducing the mixing of Atlantic and Arctic waters at the sub-surface level.
• A weakened AMOC can alter the Indian monsoon and have effects on global climate.
• Atlantic-Arctic water mixing contributes to 33% of the transformation of warm water into denser, colder water. The remaining 67% comes from ocean-atmosphere interactions.
• The Indian monsoon is a critical climate phenomenon for India, delivering about 80% of India's annual rainfall from June to September and is vital for agriculture, the economy, and public health.
• Findings from the 1980s using satellite imagery linked monsoon patterns to the movements of the Inter-tropical Convergence Zone and showed a seasonal migration from the ocean toward land.
• Concerns exist that a warming climate may slow the AMOC, leading to a southward shift of the ITCZ.
• The shift may weaken the Indian summer monsoon, impacting socio-economic factors.
• Warming of the Atlantic Ocean might accelerate the weakening of the Atlantic Meridional Overturning Circulation.
• It is a crucial current system that moderates climate across the North Atlantic and Europe.
• Ocean warming is linked to rapidly intensifying Atlantic storms, increasing risks to coastal and inland areas.
• Recent studies indicate that forests absorb less CO2 due to increased droughts and wildfires, increasing atmospheric CO2 levels.
• The Arctic tundra is shifting from a carbon sink to a source due to rising wildfire emissions.

Very Short Range Air Defence (VSHORAD) Systems

• VSHORAD launchers are in the news because of India's recent test and planned induction of DRDO-developed systems.
• They are intended to strengthen low-altitude air defence capabilities amid regional security challenges.
• VSHORADs are man-portable air defence systems (MANPADS) designed to neutralize low-flying aerial threats within 6 km.
• VSHORADs are light, compact, and quickly deployed to protect troops, convoys, and key installations.
• VSHORADs use infrared or electro-optical seekers to lock onto and destroy enemy aircraft.
• Examples of VSHORAD systems include Igla-S (Russia), RBS 70 (Sweden), FIM-92 Stinger (USA), and the indigenous system by DRDO (India).

Tropical Cyclones

• The Northern Hemisphere experiences more tropical cyclones (hurricanes/typhoons) than the Southern Hemisphere.
• The Northern Hemisphere has more warm ocean surface area with warm ocean waters (above 26.5°C) that provide latent heat energy.
• Cyclogenesis in the Intertropical Convergence Zone shifts northward.
• There are more frequent tropical disturbances and African Easterly Waves.
• Major ocean currents maintain high sea surface temperatures.
• The Northern Hemisphere has greater landmass, with stronger seasonal contrasts.
• The Southern Hemisphere's wind shear is stronger in cyclone-forming regions.

Solid State batteries

• Solid-state batteries (SSBs) are an emerging form of rechargeable battery technology being developed as the next generation of lithium-ion batteries (LIBs).

• Solid-state batteries offer improvements over conventional batteries, replacing the liquid electrolyte with a solid electrolyte.

• Anodes can be lithium metal (rather than graphite as in current LIBs). The cathode is similar to conventional LIB cathodes.

• Instead of a flammable organic liquid, SSBs use a solid electrolyte.

• Solid electrolytes can be ceramic (e.g., lithium garnet, sulfide-based compounds), polymer-based, or glass/composite materials.

• SSBs work by shuttling lithium ions from the anode to the cathode during discharge and back during charging.

• The solid electrolyte enhances safety, reduces fire risk, and allows more energy in the same space, resulting in longer-range EVs.

• Batteries can be smaller and lighter, rapid lithium-ion movement allows for faster recharge times, withstands more charge-discharge cycles, and is more resistant to performance drops.

• Solid-state batteries have high manufacturing costs, need scalability, interfacial resistance, and real-world validation.

• SSBs are used in aerospace, the military, consumer electronics, grid storage and renewable energy integration.

Metal-Organic Frameworks (MOFs) and Covalent Organic Frameworks (COFs)

• MOFs and COFs are crystalline materials designed for adsorption, separation, catalysis, and energy-related use.

• MOFs are composed of metal ions/clusters connected by organic linkers to form 3D frameworks with nano-sized pores/channels.

• They have high porosity, surface area, tunable pore size, and are responsive to temperature.

• They are utilized for carbon capture, gas storage/separation, catalysis, and energy-efficient air conditioning.

• COFs are built from light organic elements linked by covalent bonds into 2D/3D networks without metal centers.

• They have high thermal and chemical stability, predictable pore structures, are lightweight, and environmentally friendly.

• They are used for atmospheric cleansing, pollution control, and energy storage.

• Like MOFs, COFs can selectively separate gases like CO2, CH4, and H2.