Climate & Economics Glossary

A global emissions trajectory that limits long-term average surface warming to 1.5°C above pre-industrial levels (1850–1900). Requires reaching net-zero CO₂ by ~2050 and net-zero all-GHG by ~2070, along with immediate, steep reductions. The 2015 Paris Agreement's aspirational upper bound.

The cost per tonne of CO₂-equivalent avoided or removed. Expressed as $/tCO₂e. Marginal abatement cost curves (MACCs) rank mitigation options from cheapest (e.g., energy efficiency) to most expensive (e.g., direct air capture). A key tool in climate policy cost-effectiveness analysis.

Adjustments in ecological, social, or economic systems in response to actual or expected climate stimuli and their effects. Examples include sea walls, heat-resilient crop varieties, early-warning systems, and building codes for extreme weather. Distinct from mitigation, which reduces emissions.

Agriculture, Forestry and Other Land Use — an IPCC sector accounting for GHG emissions and removals from land management, livestock, crop agriculture, and forest change. One of the most complex and contested sectors due to its dual role as both emitter and sink.

Total demand for goods and services in an economy at a given price level. Comprises consumption (C), investment (I), government spending (G), and net exports (X-M). Climate shocks can suppress aggregate demand through asset destruction, higher insurance costs, and reduced labour productivity.

The fraction of incoming solar radiation reflected by a surface. Ice and snow have high albedo (~0.8); oceans and forests have low albedo (~0.06–0.15). As Arctic sea ice melts, albedo decreases, amplifying warming — the ice-albedo positive feedback.

The Paris Agreement's framework for international carbon market cooperation. Article 6.2 allows bilateral 'corresponding adjustments' between countries. Article 6.4 establishes a UN-supervised crediting mechanism (successor to CDM). Critical for achieving cost-effective global mitigation and financing developing-country action.

The premature write-down, devaluation, or conversion of assets before the end of their expected economic life due to changes in policy, technology, or climate. Fossil fuel reserves, coal plants, and carbon-intensive infrastructure face stranding risk under aggressive climate policy.

A major ocean current system carrying warm surface water from the tropics northward and returning cold deep water southward. AMOC weakening (or collapse) is a key tipping point, potentially causing severe cooling in Western Europe, sea level rise along the US East Coast, and disruption of monsoon systems.

A reference projection of emissions under a 'business-as-usual' or 'no policy' scenario, used as a benchmark for measuring the impact of mitigation actions. Baselines are inherently uncertain and contested — their design significantly affects the apparent size of emission reductions.

A development approach ensuring that after a project's impact, biodiversity is left in a measurably better state than before. Mandatory in England from 2024 under the Environment Act 2021. Linked to natural capital accounting and TNFD disclosure frameworks.

Carbon stored and sequestered by ocean and coastal ecosystems — particularly mangroves, seagrasses, and salt marshes. These ecosystems store carbon at rates up to 10× higher per unit area than terrestrial forests, and their destruction releases centuries of stored carbon rapidly.

An emissions trading system that sets a hard cap on total emissions, distributes (or auctions) allowances to emitters, and allows trading so that reductions occur where cheapest. Examples: EU ETS, California-Quebec system, RGGI (US Northeast power sector).

The EU policy (fully operational from 2026) requiring importers of carbon-intensive goods (steel, cement, aluminium, fertilisers, electricity, hydrogen) to purchase certificates matching the EU ETS carbon price for embedded emissions. Aims to prevent carbon leakage and level the playing field for EU industry.

The cumulative amount of CO₂ the world can emit while keeping warming below a temperature limit. The IPCC AR6 estimated ~380 GtCO₂ remaining for a 50% chance of limiting warming to 1.5°C from 2023. At current emissions (~40 GtCO₂/yr), this budget depletes in under a decade.

Technology that captures CO₂ from point sources (power plants, industrial facilities) and permanently stores it underground in geological formations. CCS is central to net-zero scenarios for hard-to-abate industries. Costs range from $50–120/tCO₂ for industrial applications.

The biogeochemical cycle by which carbon is exchanged among the atmosphere, oceans, terrestrial biosphere, and lithosphere. Human activities — primarily fossil fuel combustion and deforestation — have disrupted the cycle, adding ~10 GtC/yr in excess, of which ~50% remains in the atmosphere.

Methods that remove CO₂ from the atmosphere. Includes both nature-based (afforestation, soil carbon, blue carbon) and technological (DACCS, BECCS, enhanced weathering, biochar) approaches. All 1.5°C scenarios require significant CDR deployment to offset residual emissions.

The amount of CO₂ emitted per unit of economic output (kgCO₂/$GDP) or per unit of energy (gCO₂/kWh). Declining carbon intensity reflects structural economic shifts and cleaner energy, but may be offset by overall growth — the 'decoupling' challenge.

The increase in CO₂ emissions outside a country or region as a direct result of that jurisdiction's climate policies — e.g., production of carbon-intensive goods shifting to countries with weaker carbon pricing. CBAM is designed to address leakage in the EU context.

Trading systems for carbon credits and allowances. Compliance markets (e.g., EU ETS, California Cap-and-Trade) are regulated by governments. Voluntary carbon markets (VCM) allow corporates to purchase offsets. Article 6 of the Paris Agreement establishes rules for international market cooperation.

A reduction or removal of CO₂ (or equivalent GHG) elsewhere, used to compensate for emissions at the point of purchase. Quality standards (Gold Standard, Verra VCS) define additionality, permanence, and verification requirements. Offsets face scrutiny over real-world effectiveness.

A monetary value placed on CO₂ emissions to internalise the social cost of carbon. Implemented via carbon taxes or cap-and-trade systems. The IMF estimates an average global carbon price of ~$5/tCO₂ (2023), versus the $130–$200/tCO₂ needed by 2030 to meet Paris targets.

A reservoir that absorbs more carbon than it releases — primarily oceans (~26% of human emissions) and terrestrial biosphere (~31%). Climate change is reducing sink efficiency: warmer oceans absorb less CO₂; drought and fire are converting forests from sinks to sources.

A direct price on carbon emissions, typically charged to fuel producers or heavy industry per tonne of CO₂ emitted. A price-based instrument (versus cap-and-trade's quantity-based approach). Examples: Canada's federal carbon price ($80 CAD/tCO₂ in 2024), Sweden (€130/tCO₂).

Processes that amplify (positive feedback) or dampen (negative feedback) the initial warming from greenhouse gases. Key positive feedbacks: water vapour (~50% of total warming amplification), ice-albedo, permafrost methane, and cloud feedbacks. These are why climate sensitivity spans 2.5–4°C for doubled CO₂.

Funding directed toward low-carbon and climate-resilient activities. Includes public finance (multilateral development banks, bilateral aid), private finance (green bonds, blended finance), and carbon market revenues. The $100B/yr pledge to developing nations (from COP15) remained unmet until 2023.

The financial risks arising from climate change, divided into physical risks (damage from extreme weather, chronic stress) and transition risks (stranded assets, policy changes, technological disruption, and market shifts toward low-carbon). Integrated into financial regulation via TCFD and central bank stress tests.

The global mean surface temperature change from a doubling of atmospheric CO₂. Equilibrium Climate Sensitivity (ECS) is assessed by IPCC AR6 as 2.5–4°C (best estimate 3°C). Transient Climate Response (TCR, ~1.8°C) applies over 70 years of gradual CO₂ increase and is more policy-relevant.

An economy-wide model representing multiple sectors, households, and trading partners in simultaneous equilibrium. Used extensively in climate economics to assess policy impacts — e.g., how a carbon tax ripples through sectors, employment, trade, and welfare. Examples: GTAP-E, GEMINI-E3.

Under Paris Agreement Article 6.2, when a country sells a carbon credit (ITMO) to another country, it must add the credit's emissions back to its own accounting — ensuring the same reduction is not counted by both the seller and buyer. Central to avoiding double counting in international carbon markets.

A systematic framework comparing the costs and benefits of a policy or project, typically discounted to present value using a discount rate. In climate economics, CBA is complicated by long time horizons (centuries), non-linearities, irreversibilities, and the choice of discount rate — which can swing results dramatically.

The separation of economic growth from environmental impacts — specifically, growing GDP while reducing emissions or resource use. Relative decoupling means emissions grow slower than GDP. Absolute decoupling means emissions fall while GDP grows — the goal of climate policy. Rare historically; contested whether it can scale globally.

The permanent conversion of forest to non-forest land (agriculture, pasture, urban). Accounts for ~10% of global CO₂ emissions. Brazil, Indonesia, and the Democratic Republic of Congo are the primary deforestation hotspots. Deforestation also destroys biodiversity and disrupts the hydrological cycle.

A school of thought and social movement advocating for planned reduction of economic production and consumption to reduce environmental impacts, particularly in wealthy nations. Contrasts with mainstream green growth approaches. Central question: can affluent societies thrive with less GDP?

Technology that mechanically removes CO₂ directly from ambient air using chemical sorbents. Highly energy-intensive; current costs of $400–$1,000/tCO₂, projected to fall to $100–200 by 2050 at scale. Key projects: Climeworks (Iceland), 1PointFive (Texas). Required in net-zero scenarios for residual emissions offsets.

The rate used to convert future values to present values in cost-benefit analysis. A high discount rate (e.g., 5%) makes future climate damage appear small today; a low rate (e.g., Stern Review's 1.4%) makes future damage appear large, justifying greater near-term mitigation investment. One of the most contested parameters in climate economics.

Kate Raworth's economic framework defining a 'safe and just space for humanity' between a social foundation (meeting basic needs) and an ecological ceiling (planetary boundaries). Adopted by Amsterdam and other cities as a post-GDP development compass.

An advanced climate model that couples the atmosphere, ocean, land surface, sea ice, and carbon cycle — allowing it to simulate the carbon cycle feedbacks that affect CO₂ concentrations. Used in CMIP6, the model intercomparison underpinning IPCC AR6 projections.

The benefits humans receive from ecosystems. The TEEB/IPBES framework divides them into provisioning (food, water, timber), regulating (climate regulation, flood control, pollination), cultural (recreation, spiritual), and supporting (nutrient cycling, soil formation) services. Estimated global value: $125–$145 trillion/yr.

A natural climate cycle alternating between warm (El Niño) and cool (La Niña) phases of Pacific Ocean surface temperatures, with global weather impacts. El Niño years typically see record global temperatures; the 2023–24 El Niño pushed 2024 to ~1.55°C above pre-industrial, breaching the 1.5°C annual average.

The GHG emissions associated with producing a good or service, including upstream supply chain emissions (Scope 3). Critical for trade-based climate accounting; imported goods carry the emissions of their producing country. CBAM targets embedded emissions in specific trade-intensive goods.

The difference between projected global emissions under current policies and the level required to meet 1.5°C or 2°C targets. UNEP's annual Emissions Gap Report estimates this gap. In 2024, current policies lead to ~2.7°C by 2100; pledged NDCs close the gap slightly to ~2.4°C.

A market-based policy tool that sets a cap on total GHG emissions, issues tradable allowances, and lets covered entities buy and sell permits. The EU ETS is the world's largest (covering ~40% of EU emissions). Price signals incentivise emission reductions where cheapest.

Lack of access to affordable, reliable, and modern energy services. ~760 million people lack electricity access (mostly Sub-Saharan Africa); ~2.3 billion cook with polluting solid fuels. Energy poverty is intertwined with climate justice — solutions must not make energy more expensive for the vulnerable.

The global shift from fossil fuels (coal, oil, gas) to renewable and low-carbon energy sources. Characterised by rapid solar and wind deployment, electrification of transport and heat, green hydrogen, and grid modernisation. The IEA estimates $4.5 trillion/yr investment is needed by 2030.

The hypothesis that environmental degradation increases in the early stages of economic growth but decreases after a country reaches a threshold income level. Observed for local pollutants (SO₂) but debated for CO₂ — many countries have not yet achieved absolute emissions decoupling at any income level.

The world's first and largest emissions trading system, covering ~40% of EU GHG emissions from power, industry, and aviation. Phase 4 (2021–2030) tightens the cap at 4.3–4.4% per year. The EU ETS carbon price reached €100/tCO₂ in 2023 before stabilising around €60–70.

A cost or benefit from economic activity that falls on third parties not involved in the transaction. GHG emissions are the quintessential negative externality: polluters impose climate costs on society without paying for them. Carbon pricing is the standard economic remedy to internalise this external cost.

Government decisions on taxation and public spending to influence the economy. Climate-relevant fiscal tools include green subsidies (IRA tax credits), fossil fuel tax reform, public investment in infrastructure, and debt-for-nature swaps. Fiscal space — the ability to borrow and spend — varies enormously across countries.

Government support for fossil fuel production or consumption, including direct subsidies, tax breaks, and implicit subsidies (unpriced environmental damage). The IMF estimates global fossil fuel subsidies at $7 trillion in 2022 (explicit + implicit). G7 pledges to phase out inefficient subsidies have seen slow progress.

The total monetary value of all goods and services produced within a country in a given period. The dominant economic size measure, but widely criticised for excluding non-market value, wellbeing, and environmental costs. Climate damage can reduce GDP through physical destruction, productivity loss, and increased health costs.

The average surface air temperature across land and ocean globally, measured against a baseline (typically 1850–1900 pre-industrial). The primary metric for tracking warming progress toward Paris Agreement targets. 2024 was the first calendar year to exceed 1.5°C GMST above pre-industrial.

Debt instruments whose proceeds are earmarked for projects with environmental benefits — renewable energy, green buildings, sustainable transport, climate adaptation. The global green bond market exceeded $500 billion in annual issuance by 2023. ICMA's Green Bond Principles set use-of-proceeds standards.

The strategy of pursuing economic growth while ensuring that natural assets continue to provide environmental services. Championed by the OECD and World Bank as compatible with decarbonisation. Sceptics argue the empirical evidence for absolute decoupling at scale remains weak.

Hydrogen produced via electrolysis of water using renewable electricity — generating no CO₂. Current cost $3–8/kg H₂; target <$2/kg by 2030 to be competitive. Seen as key for decarbonising steel, ammonia/fertilisers, shipping, and heavy industry where direct electrification is impractical.

Atmospheric gases that absorb and re-emit infrared radiation, causing the greenhouse effect. Key GHGs: CO₂ (76% of human forcing), CH₄ methane (16%), N₂O nitrous oxide (6%), fluorinated gases (2%). Forcing is measured as CO₂-equivalent (CO₂e) using Global Warming Potential (GWP) weighting.

Bhutan's alternative to GDP, measuring wellbeing across nine domains: living standards, health, education, governance, ecology, time use, psychological wellbeing, cultural resilience, and community vitality. An influential example in the 'beyond GDP' movement.

The economic principle that the net price of an exhaustible resource should rise at the rate of interest in competitive equilibrium — reflecting the opportunity cost of extraction today versus the future. Applied to fossil fuels, it implies carbon-intensive assets will be extracted faster if investors fear future policy renders them worthless.

UNDP's composite index combining per capita income, education (mean and expected years of schooling), and life expectancy. Climate change disproportionately harms low-HDI countries, yet they have contributed least to cumulative emissions — the core equity argument in climate negotiations.

US legislation signed in August 2022, the largest climate investment in American history. Provides ~$370 billion in clean energy tax credits over 10 years for wind, solar, EVs, battery storage, hydrogen, and nuclear. The IRA's domestic content requirements and clean electricity credits are reshaping US manufacturing investment.

A model that couples climate and economic systems to evaluate emissions scenarios and policies. Used in IPCC reports to generate the Shared Socioeconomic Pathways (SSPs). Key IAMs: REMIND, IMAGE, GCAM, MESSAGE. Criticised for underestimating non-linear risks and assuming smooth technological change.

The principle of fairness between present and future generations. Central to climate ethics: current generations bear abatement costs but future generations bear the bulk of unmitigated climate damage. John Rawls' veil of ignorance and Amartya Sen's capabilities approach are often invoked in this context.

Intergovernmental Panel on Climate Change — the UN body for assessing climate science. Assessment Reports (AR) synthesise thousands of peer-reviewed papers. AR6 (2021–2022) concluded warming is unequivocally human-caused and that limiting warming to 1.5°C requires halving emissions by 2030. AR7 expected 2026–2027.

Units of GHG emission reductions traded between countries under Paris Agreement Article 6.2. A key mechanism enabling cost-efficient global mitigation — a country with cheap mitigation potential can sell ITMOs to a country where reductions are expensive. Require corresponding adjustments to avoid double counting.

The principle that the shift to a low-carbon economy should be fair and inclusive — protecting workers, communities, and developing nations that depend on fossil fuels. Includes retraining programmes, social safety nets, and targeted investment in coal-dependent regions. Central to ILO frameworks and COP30 discussions.

The first binding international treaty with quantified emission reduction targets for developed nations (Annex I parties), adopted 1997. Required ~5% reduction below 1990 levels for 2008–2012. Its market mechanisms (CDM, JI) were precursors to Article 6. The US never ratified; Canada withdrew in 2011.

Changes to how land is used — including deforestation, afforestation, peatland drainage, and conversion of grasslands to cropland. Responsible for ~11% of global GHG emissions and has significant albedo and evapotranspiration effects. The largest source of methane and N₂O in agriculture.

The net present cost of electricity generation over the lifetime of a plant per unit of energy generated ($/MWh). Allows comparison across technologies. Solar LCOE has fallen ~89% since 2010 and is now the cheapest electricity source ever recorded, below $30/MWh in resource-rich areas.

Climate impacts that cannot be adapted to — permanent losses (e.g., submerged islands, species extinction) and damages (e.g., storm losses, crop failure). The Santiago Network and the Fund for Loss & Damage (operationalised at COP28) provide finance to vulnerable developing nations experiencing unavoidable climate impacts.

The branch of economics studying the behaviour of the economy as a whole — GDP, inflation, unemployment, monetary policy, fiscal policy, trade. Climate change is increasingly integrated into macroeconomic forecasting through physical risk channels (supply shocks) and transition risk channels (stranded assets, energy price volatility).

A visual representation of mitigation options ranked by cost from cheapest to most expensive, showing cumulative emission reduction potential. McKinsey MACCs influenced early climate policy globally. Shows that energy efficiency, methane capture, and fuel switching can be negative-cost or low-cost, while DAC remains expensive.

When free markets fail to allocate resources efficiently. Climate change is the largest market failure in history (Stern): the atmosphere is an open-access commons, emissions are an unpriced externality, and information asymmetries and long time horizons prevent market solutions. Justifies government intervention.

A potent GHG with a Global Warming Potential 84× that of CO₂ over 20 years (28× over 100 years). Sources: livestock (enteric fermentation), rice paddies, wetlands, natural gas systems, coal mines, landfill. Atmospheric methane has risen >2.5× since pre-industrial. Short atmospheric lifetime (~12 years) means cuts yield rapid temperature benefits.

Actions that reduce greenhouse gas emissions or enhance carbon sinks to limit the magnitude of climate change. Includes energy efficiency, renewable deployment, fuel switching, industrial process change, and CDR. IPCC: holding to 1.5°C requires ~45% reduction in CO₂ by 2030 and net zero by ~2050.

Central bank management of money supply and interest rates to achieve macroeconomic goals (inflation, employment). Climate change increasingly affects monetary policy: physical risks drive up insurance and food prices (affecting inflation), while central banks are exploring green lending standards and climate stress tests.

The 1987 international treaty phasing out production and consumption of ozone-depleting substances (ODS) — primarily CFCs, HCFCs, and Halons. Universally ratified (197 parties); often cited as the most successful environmental treaty in history. Has prevented an estimated 2 million annual skin cancer cases. The 2016 Kigali Amendment extended the Protocol to phase down HFCs (non-ozone-depleting but potent greenhouse gases). Key remaining gap: the Protocol does not cover nitrous oxide (N₂O), now the dominant future ODS, nor rocket launch emissions. The Montreal Protocol also provided an unintended climate co-benefit: CFCs are potent GHGs, so their phaseout prevented ~0.5°C additional warming by 2100.

The world's stock of natural assets (soils, air, water, biodiversity, minerals, fossil fuels) that yield flows of ecosystem services to people and the economy. Natural capital accounting (e.g., SEEA) integrates environmental assets into national accounting. Estimated global natural capital: $44 trillion (World Bank).

Actions that protect, sustainably manage, or restore ecosystems to address societal challenges including climate change, biodiversity loss, and human wellbeing. Examples: forest protection, wetland restoration, urban greening, coastal ecosystem management. NbS can deliver ~30% of cost-effective mitigation needed by 2030.

The national climate plan each country submits under the Paris Agreement, detailing emission reduction targets and adaptation actions. NDCs are updated every 5 years and are meant to increase in ambition over time. Collectively, current NDCs put the world on track for ~2.4–2.7°C by 2100.

The sum of discounted future cash flows minus initial investment. Used to evaluate the economic viability of infrastructure, energy projects, and climate policies. The choice of discount rate is critical — a 1% higher rate can make a long-lived asset (e.g., tidal power) appear economically unviable versus a short-lived one.

Achieving a balance between GHG emissions and removals — so that no net addition of GHGs enters the atmosphere. 'Net' allows residual emissions to be offset by CDR. Climate science requires global net-zero CO₂ by ~2050 for 1.5°C. Over 140 countries have net-zero pledges, but implementation pathways vary greatly in credibility.

A coalition of central banks and financial supervisors committed to managing climate and environmental risks in the financial system and mobilising sustainable finance. Established 2017; now includes 100+ members. Publishes climate scenarios used by central banks for stress testing.

The ongoing decrease in ocean pH caused by CO₂ absorption. Ocean pH has fallen ~0.1 units since pre-industrial (a 26% increase in acidity). Acidification disrupts calcification in corals, shellfish, and pteropods, threatening marine food webs and fisheries worth ~$150 billion/yr globally.

The total thermal energy stored in the ocean, the primary indicator of Earth's energy imbalance. Oceans absorb ~90% of excess heat from greenhouse warming. Record ocean heat content set in 2023 and 2024 has accelerated sea level rise, coral bleaching, and hurricane intensification.

A region of severe stratospheric ozone depletion (column below 220 DU) occurring over Antarctica each spring (September–November), and occasionally over the Arctic in cold winters. Caused by CFC- and HCFC-derived chlorine radicals activated on polar stratospheric clouds (PSCs) that form in polar winter darkness. Peak Antarctic ozone hole area was ~27 million km² in the late 1990s; currently ~22 million km². UV-B levels beneath the ozone hole are ~50% above normal, affecting southern hemisphere agriculture (Australia, New Zealand, Chile), marine ecosystems (Southern Ocean phytoplankton productivity down 6–12%), and human health. Under the Montreal Protocol, the ozone hole is expected to close permanently by ~2066. Key remaining risks: N₂O (not regulated), illegal CFC production, and rocket emissions at high launch rates.

The landmark 2015 international climate treaty under UNFCCC, signed by 196 parties. Sets goals to limit warming to well below 2°C and pursue 1.5°C through NDCs, with a 5-year review cycle (Global Stocktake). First universal climate agreement binding both developed and developing nations.

Transactions where beneficiaries of ecosystem services (e.g., downstream water users, carbon credit buyers) pay those who manage and maintain them (e.g., forest communities). Examples: REDD+, Costa Rica's national PES scheme, watershed payments. Key instrument for valuing natural capital.

Ground that remains frozen continuously for two or more years — covering ~24% of Northern Hemisphere land. Contains ~1.5 trillion tonnes of organic carbon (roughly twice the current atmospheric CO₂ stock). Thawing permafrost releases CO₂ and methane, creating a self-reinforcing feedback loop and representing a major tipping element.

The financial risks from the physical impacts of climate change — acute (extreme weather events: floods, hurricanes, wildfires) and chronic (sea level rise, temperature increase, shifting precipitation). Physical risks affect asset values, insurance costs, agricultural productivity, and infrastructure integrity.

A tax levied on activities that generate negative externalities, set equal to the marginal social damage, to achieve the social optimum. Named after economist Arthur Pigou. Carbon taxes are the canonical application. In theory, Pigouvian taxes are more efficient than command-and-control regulation.

The Rockström et al. (2009, updated 2023) framework defining nine biophysical limits within which humanity can safely operate. Six have been transgressed (climate change, biosphere integrity, land-system change, freshwater, novel entities, biogeochemical flows). Breaching boundaries risks tipping large Earth-system processes.

A large-scale cyclonic circulation in the stratosphere (10–50 km altitude) centred over each pole during winter. Acts as a physical barrier confining cold polar air and ozone-depleted air within the polar region. A strong polar vortex keeps the Arctic ozone hole small and cold air confined to the poles. When the polar vortex weakens or splits — a Sudden Stratospheric Warming (SSW) event — cold air spills southward into mid-latitudes over 4–6 weeks, causing anomalous cold outbreaks that can paralyse infrastructure (e.g., US Winter Storm Uri, 2021: $195B damage, 246 deaths). Climate change is reducing the equator-to-pole temperature gradient, potentially increasing SSW event frequency and polar vortex disruption. Commercial rocket BC emissions may alter stratospheric heating patterns and affect vortex dynamics at high launch rates.

The change in the net downward energy flux at the tropopause due to a change in a climate driver (e.g., doubling CO₂ gives +3.7 W/m²). Positive forcing warms the planet; negative cools. Effective Radiative Forcing (ERF) includes rapid adjustments. ERF of all human activities since 1750: +2.72 W/m² (IPCC AR6).

Reducing Emissions from Deforestation and Forest Degradation + sustainable forest management and carbon stock enhancement. A UNFCCC mechanism providing results-based payments to developing countries for protecting forests. Critical for tropical nations (Brazil, Indonesia, Congo Basin). Implementation faces additionality, permanence, and leakage challenges.

Energy from sources naturally replenished on a human timescale: solar, wind, hydro, geothermal, tidal, and biomass. Renewables supplied ~30% of global electricity in 2023. IEA projects they will provide 60% by 2030 under current trajectories. Solar and wind costs have fallen 89% and 70% respectively since 2010.

The ability of a system (ecological, social, economic, or infrastructure) to absorb disturbance and reorganise while undergoing change, retaining essentially the same function. Climate resilience is a key metric for adaptation planning — distinguishing systems that can absorb impacts from those vulnerable to collapse.

The use of carbon price revenues (from taxes or auction proceeds) to achieve additional policy goals. Options include: dividend payments to citizens (British Columbia model), cutting distortionary taxes, public investment in clean energy, or funding Just Transition programmes. Revenue recycling affects political acceptability and distributional equity.

Corporate GHG accounting categories from the GHG Protocol. Scope 1: direct emissions from owned operations (e.g., on-site combustion). Scope 2: indirect emissions from purchased energy. Scope 3: all other indirect emissions in the value chain (upstream supply chain and downstream product use). Scope 3 typically represents 75–90% of corporate carbon footprints.

The increase in mean sea level driven by thermal expansion (warm water occupies more volume) and loss of ice from glaciers and ice sheets. Sea levels have risen ~20 cm since 1900 and are accelerating. Under 2°C, sea levels rise ~0.5 m by 2100; under higher scenarios, West Antarctic Ice Sheet instability could add metres over centuries.

IPCC scenarios describing five possible future socioeconomic worlds differing in their challenges to mitigation and adaptation. SSP1 (sustainability), SSP2 (middle road), SSP3 (regional rivalry), SSP4 (inequality), SSP5 (fossil-fuelled development). Combined with RCPs to generate integrated climate scenarios.

The monetised damage from emitting one additional tonne of CO₂, including effects on agriculture, health, sea level, extreme events, and ecosystems, discounted to present value. US EPA's 2023 central estimate: $190/tCO₂. The SCC is the theoretically correct carbon tax rate for optimal climate policy.

Proposed techniques to reduce incoming solar radiation to cool the planet without reducing CO₂ — e.g., stratospheric aerosol injection (SAI), marine cloud brightening, surface albedo modification. SRM could rapidly reduce temperature but does not address ocean acidification, carries governance risks, and creates termination shock if halted abruptly.

The 2006 UK government review by Lord Nicholas Stern — the most influential economic analysis of climate change. Concluded that climate change is 'the greatest market failure ever seen', and that acting early costs 1% of GDP/yr versus 5–20% GDP/yr in damages if left unchecked. Its low discount rate (1.4%) was contested by Nordhaus.

Assets that have suffered unanticipated write-downs or are premature decommissioned due to energy transition policy, technology change, or changing consumer preferences. Carbon Tracker estimates $1 trillion in potentially stranded fossil fuel assets under a 1.5°C pathway. A major systemic risk for financial stability.

The layer of ozone (O₃) concentrated in the stratosphere (15–35 km altitude), containing ~90% of all atmospheric ozone. Absorbs 97–99% of solar UV-B and 100% of UV-C radiation, protecting all surface life from DNA damage. Pre-industrial column depth: ~303 Dobson Units (DU). Currently ~291 DU globally averaged (4% depleted by CFCs, HCFCs, and other ozone-depleting substances). Recovering under the Montreal Protocol; projected to return to pre-1980 levels by ~2066. Key threats to recovery: N₂O from agriculture (not regulated by Montreal Protocol — now the dominant future ozone-depleting substance), and emerging rocket launch emissions (NOx, HCl from solid motors, and BC from kerosene vehicles deposited directly in the stratosphere). Stratospheric ozone depletion also has a slight radiative cooling effect (−0.07 W/m²), while its recovery will remove that cooling.

The vulnerability of supply chains to disruptions from climate-related physical events (e.g., floods disrupting semiconductor supply from Thailand 2011; droughts affecting food supply) or transition policy (e.g., CBAM increasing costs of imported carbon-intensive inputs). Climate TCFD guidance requires Scope 3 supply chain risk disclosure.

Framework created by the FSB under Mark Carney to standardise climate risk disclosure for financial institutions. Now replaced/superseded by ISSB's IFRS S2 standard, mandatory in many jurisdictions. Requires reporting on governance, strategy, risk management, and metrics & targets (including Scope 1, 2, 3 emissions and physical/transition risk scenarios).

Thresholds in the climate system where a small change triggers a larger, self-reinforcing shift into a new state — often irreversible on human timescales. Key tipping elements: Greenland and West Antarctic ice sheet collapse, AMOC weakening, Amazon dieback, permafrost thaw, monsoon shifts. Armstrong McKay et al. (2022) found several are reachable between 1.5–2°C.

Framework for companies and financial institutions to assess, disclose, and manage nature-related risks and opportunities. Published final recommendations September 2023. Extends TCFD's logic to biodiversity, land, water, and ocean-related risks. Uses LEAP (Locate, Evaluate, Assess, Prepare) methodology.

Garrett Hardin's (1968) concept describing how individuals, acting in self-interest, deplete shared resources. The atmosphere is the paramount commons — each country or company benefits from emitting freely while sharing climate damage with all. Justifies collective governance solutions: treaties, carbon prices, regulation.

Financial risks arising from the process of transitioning to a lower-carbon economy. Includes policy risk (carbon taxes, regulations), legal risk (climate litigation), technology risk (clean tech disruption), market risk (changing demand for fossil fuels), and reputational risk. Complementary to physical risk in climate risk frameworks.

Ground-level ozone formed in the troposphere (0–12 km) by photochemical reactions between nitrogen oxides (NOx) and volatile organic compounds (VOCs) in the presence of sunlight. Unlike stratospheric ozone (which protects the biosphere), tropospheric ozone is a harmful air pollutant and the third most important anthropogenic greenhouse gas (+0.47 W/m² forcing; IPCC AR6). Surface ozone concentrations have risen ~40% since pre-industrial (~25 ppb → ~35 ppb). Causes ~10% global crop yield loss (wheat, soybean, rice particularly sensitive) and ~1 million premature deaths per year from respiratory disease. Relatively short atmospheric lifetime (weeks), so reducing NOx and VOC precursors yields rapid air quality and climate benefits.

United Nations Framework Convention on Climate Change — the 1992 international treaty providing the foundation for global climate action. 198 parties. The UNFCCC secretariat hosts annual COP meetings and oversees NDC submissions, transparency mechanisms (ETF), and the Paris Agreement's implementation architecture.

Solar ultraviolet radiation in the 280–315 nm wavelength band. Under the intact ozone layer, ~5–10% reaches Earth's surface; the rest is absorbed by stratospheric ozone. UV-B is biologically very active: it damages DNA, suppresses immune responses, causes skin cancer and cataracts, inhibits phytoplankton photosynthesis, and reduces crop yields. Radiation Amplification Factor (RAF): each 1% decrease in the ozone column increases biologically effective UV-B by approximately 2% (erythemal dose) to 3% (DNA damage). Current ozone depletion (~4%) has elevated UV-B globally by ~8%, costing an estimated $70 billion/year in health, agricultural, and ecosystem damage. Recovery of the ozone layer under the Montreal Protocol will reduce this cost — but N₂O increases and commercial rocket launch growth could delay or reverse the recovery.

Markets where companies and individuals voluntarily purchase carbon credits (offsets) to compensate for emissions. Reached $2 billion in 2021 before scrutiny over credit quality caused contraction. Key standards: Verra VCS, Gold Standard, ACR. ICVCM's Core Carbon Principles (2023) aim to raise quality floor.

The degree to which a system is susceptible to, or unable to cope with, adverse effects of climate change. A function of exposure (to climate hazards), sensitivity (of the system to those hazards), and adaptive capacity (ability to adjust). Small Island Developing States, Least Developed Countries, and Sub-Saharan Africa have highest vulnerability.

The interdependencies between water availability, energy production, and food security. Climate change disrupts all three simultaneously: droughts reduce hydropower and irrigation; heatwaves cut crop yields and reduce thermal power cooling efficiency; groundwater over-extraction depletes reserves for agriculture and energy. Requires integrated governance.

The branch of economics evaluating the well-being of individuals and societies, using concepts such as utility, efficiency (Pareto optimality), equity, and social welfare functions. Climate economics is fundamentally a welfare problem: how to weigh current versus future welfare, and whose welfare counts in global policy design.

An economic paradigm that prioritises human and planetary wellbeing over GDP growth. The Wellbeing Economy Governments (WEGo) partnership (Scotland, Iceland, New Zealand, Wales, Finland, Canada) adopts metrics such as health, social connection, and ecological integrity as primary policy targets.