Topic 6

Atmosphere

A mixture of gases that surrounds the Earth, held in place by gravity, which acts as a dynamic system supporting life and regulating the planet's temperature.

Radiation

The emission of energy as electromagnetic waves; in environmental systems, this includes short-wave solar radiation from the Sun and long-wave infrared radiation emitted by the Earth.

Greenhouse Gases

Gases such as carbon dioxide (CO2CO2), methane (CH4CH4), and water vapor that absorb and re-emit long-wave infrared radiation, trapping heat within the atmosphere.

Radiative forcing

A measure of the influence a factor has in altering the balance of incoming and outgoing energy in the Earth-atmosphere system,

Aerosols

Microscopic solid particles or liquid droplets (such as dust, soot, or sulfates) suspended in the atmosphere that can reflect or absorb radiation, influencing climate.

Troposphere

The lowest layer of the atmosphere, extending from the surface to approximately 12km12km, where temperature decreases with altitude and most weather systems occur.

Mesosphere

The atmospheric layer above the stratosphere (approx. 50−85km50−85km) where temperatures decrease with height, reaching the coldest temperatures in the atmosphere.

​Tropopause

The boundary layer between the troposphere and the stratosphere that acts as an isothermal lid, preventing further vertical mixing of air and weather systems.

Stratosphere

The layer above the troposphere containing the ozone layer, which absorbs UV radiation and causes temperature to increase with altitude.

Atmospheric gases

The collective mixture of nitrogen (78%78%), oxygen (21%21%), argon (0.9%0.9%), and trace amounts of other gases like carbon dioxide and water vapor.

Ice cores

Cylindrical samples removed from ice sheets or glaciers that contain trapped gas bubbles and isotopes, providing proxy data to reconstruct past atmospheric composition and temperature.

Tree rings (dendrochronology)

The study of the annual growth rings in trees to determine past environmental conditions such as temperature and moisture availability.

Sediment deposits

Layers of organic and inorganic material at the bottom of water bodies that serve as proxy records of past climatic and environmental shifts.

CO2 concentration

The measure of carbon dioxide in the atmosphere, currently exceeding 400 ppm400ppm, which is the principal gas contributing to the enhanced greenhouse effect.

Glacial cycles

The natural fluctuations of Earth's climate between periods of ice advance (glacials) and ice retreat (interglacials), primarily driven by orbital variations.

Proxy data

Indirect evidence of past climate (e.g., pollen, ice cores, tree rings) used to reconstruct climatic conditions before the era of instrumental records.

​Biome shifts

The migration of large-scale ecological communities to new latitudes or elevations in response to changing temperature and precipitation patterns.

Ice-albedo effect

A positive feedback mechanism where a reduction in ice cover lowers reflectivity, leading to increased heat absorption and further melting.

Permafrost thawing

The melting of ground that has remained frozen for two or more years, which releases stored methane (CH4CH4) and CO2CO2 into the atmosphere.

Carbon sinks

Natural or human-made reservoirs, such as forests or oceans, that absorb and store more carbon from the atmosphere than they release.

Methane release

The discharge of CH4CH4​ into the atmosphere from sources such as wetlands, livestock, or melting permafrost; it is a potent greenhouse gas.

Amplification

A process in which an initial climate change triggers feedback loops that increase the overall magnitude of the climatic response.

Climate resilience

The capacity of social or ecological systems to absorb climate impacts, adapt to changes, and recover while maintaining essential functions.

Emission rates

The total amount of greenhouse gases or pollutants released into the atmosphere per unit of time from human or natural sources.

Climate Change Mitigation

Actions and strategies intended to reduce or prevent the emission of greenhouse gases, such as transitioning to renewable energy or enhancing carbon sinks.

Adaptation strategies

Adjustments made in human or natural systems to cope with the actual or expected effects of climate change, such as building sea walls or developing heat-resistant crops.

Geoengineering

The deliberate, large-scale manipulation of environmental processes, such as solar radiation management or carbon dioxide removal, to counteract global warming.

Carbon capture and storage (CCS)

A technology that captures CO2CO2​ emissions from industrial sources, transports them, and stores them deep underground to prevent them from entering the atmosphere.

Carbon pricing

An economic strategy that puts a financial cost on carbon emissions, typically via a tax or trading system, to incentivize businesses to reduce their greenhouse gas output.

Paris Agreement

An international treaty adopted in 20152015 with the goal of limiting global warming to well below 2∘C2∘C above pre-industrial levels, aiming for a limit of 1.5∘C1.5∘C.

Carbon trading

A market-based system, also known as cap-and-trade, where a limit is set on total emissions and companies trade permits, incentivizing the most cost-effective emission reductions.