Tag: science & technology

Sea level rise occurs through two main physical mechanisms: thermal expansion (ocean water occupies more volume when warmed) and addition of meltwater from glaciers and ice sheets. Both processes are direct consequences of global warming and contribute significantly to observed and projected sea level rise.

Over the 20th century, global sea level rose approximately 10-20 cm, with option B (10-12.5 cm) being the closest. This rise is primarily due to thermal expansion of seawater and melting glaciers. Option A's range (20-25 cm) is too high for the past century.

Climate change has wide-ranging impacts: it affects agriculture (crop yields), terrestrial ecosystems (species ranges), water resources (droughts/floods), air quality (stagnation), oceans (acidification), coastal zones (sea-level rise), energy demand, and human health. Therefore, 'all of the above' is correct.

In India, electric power generation is the largest source of greenhouse gas emissions, primarily from coal-fired power plants. The transport sector is significant but smaller, while agriculture (methane from livestock, rice paddies) and domestic sectors contribute less.

The 1992 Rio Earth Summit (UN Conference on Environment and Development) was the first major global conference to establish the UN Framework Convention on Climate Change (UNFCCC), representing the first step toward coordinated greenhouse gas reduction. The Vienna Convention (1985) and Montreal Protocol (1987) addressed ozone depletion, not climate change.

The Antarctic ozone hole was first discovered in 1985 by a team of British scientists (Farman, Gardiner, and Shanklin) using ground-based measurements from Halley Bay station. This finding was published in Nature and led to accelerated international action on ozone protection, including the Montreal Protocol strengthening.

The Montreal Protocol (1987) is the international treaty that phases out ozone-depleting substances like CFCs and HCFCs. India ratified this protocol and committed to phase-out schedules. The Vienna Convention (1985) provided the framework but doesn't set phase-out limits. Basel Convention addresses hazardous waste trade, while Agenda 21 covers sustainable development broadly.

All three mechanisms contribute to sea-level rise from warming: (1) thermal expansion as ocean water heats and occupies more volume; (2) melting mountain glaciers and ice caps adding freshwater; (3) melting and sliding of Greenland and Antarctic ice sheets into oceans. The combined effect is projected at ~50cm by 2100 for 2°C warming.

Freon is the trade name for CFCs (chlorofluorocarbons) commonly used as refrigerants in refrigerators and air conditioning systems. CFCs are potent greenhouse gases that also damage the ozone layer. Carbon dioxide, methane, and ammonia are not CFCs - CO2 is a natural greenhouse gas, methane is from organic decomposition, and ammonia is a different refrigerant.

Naphtha is a flammable liquid hydrocarbon mixture. Because its boiling range and chemical properties are somewhat similar to petrol, it is frequently used as an illegal adulterant in fuel markets.