Greenhouse Gas Protocol Emission Scopes

The process of capturing carbon dioxide (CO2) from large point sources like power plants and injecting it into deep underground rock formations for long-term storage. Suitable formations include saline aquifers, depleted oil and gas reservoirs, and unmineable coal seams. The CO2 is trapped by an impermeable caprock and through various physical and chemical mechanisms, preventing its atmospheric release.

The Ecological Footprint is a resource accounting metric that measures human demand on nature. It quantifies the amount of biologically productive land and sea area required to produce the resources a population consumes (like food, fiber, and timber), and to absorb its waste, especially carbon emissions. It is the 'demand' side of the Earth Overshoot Day (EOD) calculation.

The Kaya identity is a mathematical formula stating that the total emission level of carbon dioxide can be expressed as the product of four factors: human population, GDP per capita, energy intensity (energy per unit of GDP), and carbon intensity (emissions per unit of energy). The formula is \(F = P \times \frac{G}{P} \times \frac{E}{G} \times \frac{F}{E}\), where F is CO2 emissions, P is population, G is GDP, and E is energy consumption.

Secondary Organic Aerosols (SOAs) are fine airborne particles formed from the atmospheric oxidation of VOCs. Gaseous VOCs react with oxidants like \(O_3\), \(\bullet OH\), or \(NO_3\bullet\) to produce low-volatility products. These products can then undergo gas-to-particle conversion, either by forming new particles (nucleation) or condensing onto pre-existing aerosols. SOAs are a major component of PM2.5, impacting climate and human health.

Involves capturing CO2 and storing it in the deep ocean, which is the planet's largest carbon sink. Methods include direct injection of liquid CO2 into the water column or onto the deep seafloor, and ocean fertilization to stimulate phytoplankton growth, which absorbs CO2 via photosynthesis. Both approaches have significant environmental concerns, primarily ocean acidification and unpredictable impacts on marine ecosystems.

Biocapacity is a metric that represents the biosphere's regenerative capacity in a given year. It measures the amount of biologically productive land and sea area available to provide resources and absorb wastes under current management practices. It is the 'supply' side of the ecological balance sheet used to calculate Earth Overshoot Day, measured in global hectares (gha).

Earth Overshoot Day (EOD) is the calculated illustrative calendar date on which humanity's demand for ecological resources and services in a given year exceeds what Earth can regenerate in that year. It marks the point where human consumption shifts from using the planet's annual ecological interest to depleting its principal natural capital, effectively living on credit.