Global Warming Practice Questions

Global warming is the long-term rise in Earth’s average surface temperature due to increased greenhouse gases.

As of 2024, warming is about 1.2-1.3°C, with 2024 ~1.48°C above pre-industrial in some datasets.

2011-2020 was warmest decade, with 2020s on track to surpass it.

Burning fossil fuels for energy releases CO2, the dominant driver.

CO2 persists centuries to millennia; methane ~12 years, N2O ~109 years.

Water vapour is a feedback, not a forcing, because its concentration responds to temperature.

Rapid rise in Northern Hemisphere temperatures in 20th century compared to past 1000 years.

Troposphere, where greenhouse gases concentrate, traps outgoing infrared.

CO2 is reference gas with GWP =1.

Ozone depletion cools stratosphere but does not directly warm surface like GHGs.

Arctic warms 2-4 times faster than global average due to ice-albedo feedback.

Greenland ice sheet melting plus thermal expansion dominate current rise; Antarctica accelerating.

Sea ice already displaces water (Archimedes principle), but it reduces albedo.

Limit to 1.5°C above 1850-1900 average.

2024 saw multiple months and annual average near/above 1.5°C in some datasets, though not yet long-term.

UHI is local effect, contributes <1% to global average, but affects local records.

Mount Pinatubo eruption 1991 injected aerosols, cooling ~0.5°C for 2 years.

Solar output has slightly declined since 1980s, cannot explain warming.

Greenhouse blocks convection; atmosphere traps infrared radiation.

Ice-albedo, water vapour, permafrost methane are positive feedbacks.

Increased low cloud cover could reflect sunlight (negative), but uncertain.

Heatwaves, heavy rainfall, droughts increase; cold extremes decrease.

Oceans absorb ~90% of excess heat from global warming.

About 40-50%, rest from ice melt.

Europe and Arctic regions warming fastest; Europe ~2x global rate.

Equilibrium warming for doubling of CO2, estimated 2.5-4°C (IPCC AR6).

CO2 rising steadily due to human emissions, correlating with warming.

Energy sector (power, transport, industry) ~70% of India’s GHGs.

Absorbs sunlight, darkens snow reducing albedo.

Weather is short-term; climate is long-term average (30+ years).

Warm, acidify, and deoxygenate.

Himalayan region, especially Sikkim, Uttarakhand, Himachal.

EU adopted 1996, formalized in Copenhagen Accord 2009.

Determining how much climate change influenced specific extreme events.

Methane ~160% increase (700 ppb to ~1920 ppb), CO2 ~50%.

Very high GWP (thousands) and long lifetimes.

Oceans and terrestrial biosphere (forests, soils) absorb ~50% of emissions.

Species ranges, storm tracks, agricultural zones shift poleward.

More intense heatwaves, erratic monsoon, increased heat-related deaths.

Reduction in sunlight reaching surface due to aerosols, partially masked warming.

Unmask warming, causing faster temperature rise short-term.

IPCC Assessment Reports (AR6 2021-2023).

Future warming locked in from past emissions due to ocean thermal inertia.

Estimate total CO2 that can be emitted to stay below temperature target.

Phalodi, Rajasthan recorded 51°C in 2016; Delhi crossed 49°C in 2022-24.

Warmer air holds ~7% more moisture per °C (Clausius-Clapeyron).

Net zero requires deep cuts plus removals across all GHGs; carbon neutral often offsets only.

Permafrost carbon release and ice-albedo are strong Arctic feedbacks.

Combination of land stations, ships, buoys, satellites, homogenized datasets.

Loss of sea ice reduces albedo, exposing dark ocean absorbing heat.