Climate Science and Global Carbon Cycles

Vocabulary flashcards covering fundamental climate concepts, greenhouse gas dynamics, physical laws, methane sources/sinks, and geological climate transitions.

Null Hypothesis (Climate Science)

The presumption that natural changes in Earth's climate always occur and can explain global warming unless evidence demonstrates otherwise.

Wien's Law

A physical law stating that an object's absolute temperature ($T$) determines its radiation peak wavelength ($\lambda$).

Stefan-Boltzmann Law

A physical law represented by $F = \text{physical constant} \times T^4$, calculating the radiation flux ($F$) of an object based on its temperature ($T$).

Watt

A unit measuring the rate of energy flow, defined as Joules per second ($\text{J\,s}^{-1}$).

Residence Time

The average duration a greenhouse gas molecule remains in the atmosphere, dependent upon the gas's input, output, and reservoir size.

National Academy of Sciences

An organization founded in 1863 by President Abraham Lincoln composed of elected scientists to provide independent, objective advice to the United States.

Area Flux Mappers

Satellite systems that measure atmospheric methane concentrations over relatively large geographic regions, such as the northeastern United States.

Point Source Imagers

Satellite instruments designed to identify and pinpoint high-volume individual point sources of methane emissions.

Top-Down Approach

An emissions estimation method that measures atmospheric gas concentrations using towers, aircraft, or satellites and couples data with models to estimate regional or global totals.

Bottom-Up Approach

An emissions estimation method that measures or models emissions from individual, smaller sources (such as natural gas wells or cattle farms) and scales them up to regional or national levels.

Methanotrophs

Bacteria or archaea inhabiting moist, oxygenated soils that metabolize ("eat") methane as a carbon and energy source.

Methanogens

Archaea that generate methane as a metabolic byproduct in zero-oxygen (hypoxic) environments, such as wetlands, landfills, and wastewater treatment ponds.

Enteric Fermentation

A digestive process in the stomach (rumen) of ruminant animals like cattle, where microbes generate methane that is primarily expelled through burps.

Paris Climate Agreement

A legally binding international climate treaty adopted in 2015 by 195 parties to limit global warming to well below $2\,^\circ\text{C}$, aiming for $1.5\,^\circ\text{C}$.

Remaining Carbon Budget

The maximum cumulative amount of $\text{CO}_2$ that can be emitted into the atmosphere while maintaining a given probability of stabilizing warming below a specific threshold.

Shared Socioeconomic Pathways (SSPs)

Climate scenarios designed to span potential future socioeconomic outcomes, where the trailing number indicates radiative forcing in $\text{W\,m}^{-2}$.

Planetary Albedo

The measure of Earth's surface reflectivity to incoming sunlight, which decreases as reflective ice melts, creating a positive climate feedback.

Aerosols

Small liquid or solid particles suspended in the air ($1$ to $100{,}000\,\text{nm}$ in size) that generally act as a cooling brake on global warming by reflecting sunlight.

Sulfate Aerosols

Toxic secondary aerosols created when sulfur dioxide ($\text{SO}_2$) from fossil fuel combustion or volcanic eruptions reacts chemically with atmospheric gases.

Greenhouse Climate State

A long-term planetary climate state defined by warm temperatures and an absence of continental ice sheets.

Icehouse Climate State

A long-term planetary climate state characterized by global conditions cold enough to support continental ice sheets.

Interglacial Period

A warmer climate interval within an icehouse state during which continental ice sheets retreat.

Glacial Period

A colder climate interval within an icehouse state during which continental ice sheets advance.

Glacial Moraines

Accumulations of unsorted rock and soil debris deposited at the boundaries of melting glaciers.

Glacial Striations

Grooves carved into bedrock surfaces by rock fragments embedded in advancing glaciers.

Permian-Triassic Mass Extinction Event

"The Great Dying" event occurring roughly 250 million years ago, where volcanic $\text{CO}_2$ emissions from the Siberian Traps caused dramatic warming and severe impacts on life.

Siberian Traps

A massive volcanic system whose eruptions 250 million years ago elevated atmospheric $\text{CO}_2$ approximately 4 times, triggering global warming during the Permian-Triassic extinction.

Stomata

Microscopic openings on plant leaves that close when atmospheric $\text{CO}_2$ levels are high and open when $\text{CO}_2$ levels are low.

El Niño-Southern Oscillation (ENSO)

A natural climate cycle occurring in the tropical Pacific Ocean every 3 to 7 years, alternating between warm (El Niño) and cold (La Niña) phases that impact global temperatures.

Climate Sensitivity

The expected global warming in Celsius resulting from a doubling of atmospheric carbon dioxide ($2\times\text{CO}_2$), estimated to cause $2.5\,^\circ\text{C}$ to $4.0\,^\circ\text{C}$ of warming.