Earth System Sciences and Climate Change

Comprehensive vocabulary flashcards covering the Earth's spheres, biogeochemical cycles, atmospheric and oceanic dynamics, radiative forcing, paleoclimatology, and climate adaptation and mitigation strategies.

Geosphere

The largest Earth sphere, extending from the surface to the center of the planet, categorized by composition into the crust, mantle, and core.

Biosphere

The sum of all ecosystems containing all living organisms on Earth, encompassing microbes, viruses, fungi, plants, algae, animals, and humans.

Cryosphere

The subsystem of the Earth system comprising frozen water in the form of snow, permafrost, glaciers, ice sheets, and sea ice in regions such as the Arctic and Antarctica.

Lithosphere

The rigid external physical layer of the Earth composed of the crust and the uppermost solid mantle, measuring $0\text{--}100\,\text{km}$ in thickness.

Asthenosphere

The heat-softened, slow-flowing yet solid rock layer in the upper mantle situated $100\text{--}350\,\text{km}$ beneath Earth's surface, designated as the weak layer.

Oceanic Crust

The thin crust underlying ocean basins composed of the volcanic rock basalt, with an average density of approximately $3.0\,\text{g/cm}^3$.

Continental Crust

The thick crust underlying continents with a highly variable, on-average granite-like composition and an average density of approximately $2.7\,\text{g/cm}^3$.

Ring of Fire

A major tectonic belt along the rim of the Pacific Ocean (Circum-Pacific Belt) characterized by frequent earthquakes and active volcanoes.

Biome

A major regional community of plants and animals classified according to predominant vegetation and climate, consisting of many individual ecosystems.

Primary Productivity

The rate at which primary production occurs, measuring the speed of new organic biomass accumulation through photosynthesis.

Chlorophyll

The central photosynthetic pigment that absorbs blue and red wavelengths while reflecting green light, converting solar energy into chemical energy.

Evapotranspiration

The combined transfer of water into the atmosphere from evaporation off wet surfaces and transpiration from plant leaves through stomata.

Stem Flow

Rainfall intercepted by plant canopies that drains down leaves and stems directly to the ground surface.

Percolation

The slow downward movement of water passing through porous materials like soil or bedrock.

Aquifer

A permeable, water-bearing rock stratum or sediment (such as sand or gravel) capable of transmitting groundwater freely.

Aquitard

An impermeable geologic layer (such as clay) that impedes or completely blocks the movement of groundwater.

Coriolis Force

An apparent force resulting from Earth's rotation that deflects moving fluids and objects to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

Ekman Transport

The net $90^\circ$ movement of a surface water layer relative to wind direction, caused by wind shear and the Coriolis deflection, frequently driving coastal upwelling.

Thermohaline Circulation (THC)

A global deep-ocean conveyor-belt circulation system driven by density gradients originating from variations in water temperature and salinity, cycling on an approximately $1000$-year timescale.

Heterosphere

The upper atmospheric zone extending from $80\,\text{km}$ up to the exosphere, containing under $0.001\%$ of total mass, where gases are stratified into distinct layers by atomic weight.

Homosphere

The lower atmospheric zone below approximately $80\,\text{km}$, where gases are uniformly mixed through continuous turbulence and circulation.

Noctilucent Clouds

Tenewous, high-altitude cloud-like phenomena composed of ice crystals in the mesosphere, visible only during astronomical twilight.

Stratosphere

The stable atmospheric layer extending between approximately $18\,\text{km}$ and $50\,\text{km}$ containing the ozone layer, characterized by minimal convective mixing.

Troposphere

The lowest atmospheric layer ($0\text{--}18\,\text{km}$) that contains $90\%$ of all atmospheric mass and virtually all weather phenomena, water vapor, and air pollution.

Biodiversity Hotspot

A biogeographical region that contains at least $1,500$ endemic native vascular plant species and has lost at least $70\%$ of its primary native vegetation.

Radiative Forcing (RF)

A metric quantified in $\text{W/m}^2$ that measures the capacity of a gas or forcing agent to alter Earth's energy balance and shift global temperatures.

Global Dimming

A reduction in solar irradiance reaching Earth's surface caused by suspended aerosols that increase aerosol optical thickness and create more reflective cloud droplets.

Black Carbon

A product of incomplete combustion of fossil fuels and biomass that exerts positive radiative forcing by darkening snow and ice and absorbing solar energy.

Ocean Acidification

The sustained reduction of ocean pH caused by chemical absorption of atmospheric $\text{CO}_2$, which creates carbonic acid and reduces ambient carbonate ion ($\text{CO}_3^{2-}$) concentration.

Aragonite Saturation State

A chemical metric indicating the thermodynamic ease with which marine organisms can form and preserve calcium carbonate shells and skeletons.

Permafrost

Subsurface soil, sediment, or rock that remains at or below $0\,{{^\circ}\text{C}}$ continuously for at least two consecutive years.

Milankovitch Cycles

Periodic cyclical changes in Earth's axial tilt and orbital geometry that modify solar insolation at $65^\circ\text{N}$, triggering glacial and interglacial episodes.

Trigger and Rate of Climate Change (Past vs. Today)

Past climate change was driven gradually by orbital fluctuations altering solar forcing, whereas contemporary climate change is driven at a much higher rate by excess release of greenhouse gases.

Impacted Systems under Climate Change

The classification of planetary impacts across physical systems (e.g., droughts, floods, sea level rise), biological systems (e.g., wildfires, insect threats, coral reef loss), and human systems (e.g., food production changes, migration, disease spread).

Shared Socio-economic Pathways (SSPs)

Quantitative socio-economic scenarios adopted by the IPCC (e.g., SSP1-1.9 through SSP5-8.5) projecting future development trajectories and their corresponding radiative forcing levels in the year $2100$.

Nationally Determined Contributions (NDCs)

Formal non-binding climate plans submitted under Article 4 of the Paris Agreement outlining each country's planned greenhouse gas reductions and adaptation targets.

Coping (Climate Change)

Short- to medium-term tactical responses using available resources to manage adverse climate impacts without modifying long-term system vulnerability, often degrading the local resource base.

Climate Adaptation

A structured, iterative local process of adjustment in human or natural systems to actual or expected climate effects in order to moderate harm or exploit beneficial opportunities.

Climate Mitigation

Human interventions and global strategies aimed at reducing greenhouse gas emissions at the source or enhancing carbon sinks that draw down greenhouse gases from the atmosphere.

Climate Vulnerability

The degree to which a system is susceptible to harm from climate change, defined as a function of exposure, sensitivity, and adaptive capacity: $\text{Vulnerability} = f(\text{Exposure}, \text{Sensitivity}, \text{Adaptive Capacity})$.

Polders

Low-lying coastal land tracts enclosed by protective dikes that have been drained and reclaimed from coastal or tidal waters, as used in Dutch flood management.

AFOLU

Agriculture, Forestry, and Other Land Use; a major emissions sector encompassing direct agricultural emissions (such as enteric fermentation and fertilizer use) and deforestation.

Carbon Capture and Storage (CCS)

A process involving separating waste $\text{CO}_2$ from industrial point sources, transporting it, and injecting it into deep underground geological formations for permanent isolation.

Direct Air Capture (DAC)

An engineered method of removing $\text{CO}_2$ directly from ambient air using chemical sorbents or solvents to produce a concentrated stream for geological storage or utilization.

Bioenergy with Carbon Capture and Storage (BECCS)

A negative-emissions technology where biomass that captured atmospheric carbon during growth is converted into energy, with the resulting $\text{CO}_2$ captured and stored underground.

Solar Radiation Management (SRM)

A category of geoengineering that proposes modifying Earth's albedo—such as through stratospheric aerosol injection or marine cloud brightening—to reflect incoming sunlight back into space.