Editing IPCC:AR6/Data/Glossary (section)

== G ==

<div class="glossary-entry">
<div id="Gender_equity"></div>
=== <span class="glossary-term">Gender equity</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGIII</div>

<div class="glossary-definition">'''Definition:''' Equity between women and men with regard to their rights, resources and opportunities. In the case of climate change, gender equity recognises that women are often more vulnerable to the impacts of climate change and may be disadvantaged in the process and outcomes of climate policy.</div>
</div>

<div class="glossary-entry">
<div id="General_circulation"></div>
=== <span class="glossary-term">General circulation</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI</div>

<div class="glossary-definition">'''Definition:''' The large-scale motions of the atmosphere and the ocean as a consequence of differential heating on a rotating Earth. General circulation contributes to the energy balance of the system through transport of heat and momentum.</div>
</div>

<div class="glossary-entry">
<div id="General_circulation_model"></div>
=== <span class="glossary-term">General circulation model</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI</div>

<div class="glossary-longer-term">'''Full term:''' General circulation model (GCM)</div>

<div class="glossary-definition">'''Definition:''' A numerical representation of the atmosphere–ocean–sea ice system based on the physical, chemical and biological properties of its components, their interactions and feedback processes. General circulation models are used for weather forecasts, seasonal to decadal prediction, and climate projections. They are the basis of the more complex Earth system models (ESMs).</div>
</div>

<div class="glossary-entry">
<div id="Geocentric_sea_level_change"></div>
=== <span class="glossary-term">Geocentric sea level change</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI</div>

<div class="glossary-definition">'''Definition:''' The change in local mean sea surface height with respect to the terrestrial reference frame; it is the sea level change observed with instruments from space.</div>
</div>

<div class="glossary-entry">
<div id="Geoid"></div>
=== <span class="glossary-term">Geoid</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI</div>

<div class="glossary-definition">'''Definition:''' The equipotential surface having the same geopotential at each latitude and longitude around the world (geodesists denote this potential W0) that best approximates the mean sea level. It is the surface of reference for measurement of altitude. In practice, several variations of definitions of the geoid exist depending on the way the permanent tide (the zero-frequency gravitational tide due to the Sun and Moon) is considered in geodetic studies.</div>
</div>

<div class="glossary-entry">
<div id="Geostrophic_winds_or_currents"></div>
=== <span class="glossary-term">Geostrophic winds or currents</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI</div>

<div class="glossary-definition">'''Definition:''' A wind or current that is in balance with the horizontal pressure gradient and the Coriolis force, and thus is outside of the influence of friction. Thus, the wind or current is directly parallel to isobars and its speed is proportional to the horizontal pressure gradient.</div>
</div>

<div class="glossary-entry">
<div id="Geothermal_energy"></div>
=== <span class="glossary-term">Geothermal energy</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGIII</div>

<div class="glossary-definition">'''Definition:''' Accessible thermal energy stored in the Earth’s interior, in both rock and trapped steam or liquid water (hydrothermal resources), which may be used to generate electric energy in a thermal power plant, or to supply heat to any process requiring it. The main sources of geothermal energy are the residual energy available from planet formation and the energy continuously generated from radionuclide decay.</div>
</div>

<div class="glossary-entry">
<div id="Gini_coefficient"></div>
=== <span class="glossary-term">Gini coefficient</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGIII</div>

<div class="glossary-definition">'''Definition:''' A statistical measure of dispersion in a distribution and degree of mathematical measure of inequality. For example, it can be used for measuring inequality in income, wealth, carbon emissions, and access to well-being defining services. The dimensionless GINI coefficient ranges between 0 (absolute equality) and 1 (absolute inequality).</div>
</div>

<div class="glossary-entry">
<div id="Glacial-interglacial_cycles"></div>
=== <span class="glossary-term">Glacial-interglacial cycles</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI</div>

<div class="glossary-definition">'''Definition:''' Phase of the Earth’s history marked by large changes in continental ice volume and global sea level.</div>
</div>

<div class="glossary-entry">
<div id="Glacial_isostatic_adjustment"></div>
=== <span class="glossary-term">Glacial isostatic adjustment</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI</div>

<div class="glossary-longer-term">'''Full term:''' Glacial isostatic adjustment (GIA)</div>

<div class="glossary-definition">'''Definition:''' The ongoing changes in gravity, rotation and viscoelastic solid Earth deformation (GRD) in response to past changes in the distribution of ice and water on Earth’s surface. On a time scale of decades to tens of millennia following mass redistribution, Earth’s mantle flows viscously as it evolves toward isostatic equilibrium, causing solid Earth movement and geoid changes, which can result in regional-to-local sea level variations.</div>
</div>

<div class="glossary-entry">
<div id="Glacial_lake_outburst_flood__Glacier_lake_outburst"></div>
=== <span class="glossary-term">Glacial lake outburst flood /Glacier lake outburst</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI; WGII</div>

<div class="glossary-longer-term">'''Full term:''' Glacial lake outburst flood (GLOF)/Glacier lake outburst</div>

<div class="glossary-definition">'''Definition:''' A sudden release of water from a glacier lake, including any of the following types: a glacier-dammed lake, a pro-glacial moraine-dammed lake or water that was stored within, under or on the glacier.</div>
</div>

<div class="glossary-entry">
<div id="Glacial_or_glaciation"></div>
=== <span class="glossary-term">Glacial or glaciation</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI</div>

<div class="glossary-definition">'''Definition:''' A period characterized by the establishment of expanded ice sheets and glaciers, and associated with global mean sea level (GMSL) substantially lower than present; generally coincides with even-numbered marine isotope stages. Glacial intervals were interrupted by interglacial intervals. The Last Glacial Maximum (LGM) is a specific interval within the most recent glaciation, when ice sheets were near their global maximum volume (Clark et al., 2009; Gowan et al., 2021) and GMSL was nearly at its lowest level (Lambeck et al., 2014; Yokoyama et al., 2018). Local or regional glacial maxima may be diachronous, for example ranging from about 29,000 years ago and 16,000 years ago. For purposes of global synthesis, IPCC AR6 adopts a practical chronostratigraphic definition of LGM of 23,000–19,000 years BP (before 1950; chronozone level 1 of Mix et al., 2001). For modelling purposes, LGM is defined by the model time step nearest to the centre of this interval, 21,000 years ago (Kageyama et al., 2017).</div>
</div>

<div class="glossary-entry">
<div id="Glaciated"></div>
=== <span class="glossary-term">Glaciated</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI</div>

<div class="glossary-definition">'''Definition:''' State of a surface that was covered by glacier ice in the past, but not at present.</div>
</div>

<div class="glossary-entry">
<div id="Glacier"></div>
=== <span class="glossary-term">Glacier</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI; WGII</div>

<div class="glossary-definition">'''Definition:''' A perennial mass of ice, and possibly firn and snow, originating on the land surface by accumulation and compaction of snow and showing evidence of past or present flow. A glacier typically gains mass by accumulation of snow and loses mass by ablation. Land ice masses of continental size (>50,000 km2) are referred to as ice sheets (Cogley et al., 2011).</div>
</div>

<div class="glossary-entry">
<div id="Glacierized"></div>
=== <span class="glossary-term">Glacierized</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI</div>

<div class="glossary-definition">'''Definition:''' A surface that is currently covered by glacier ice.</div>
</div>

<div class="glossary-entry">
<div id="Global_Environment_Facility"></div>
=== <span class="glossary-term">Global Environment Facility</span> ===

<div class="glossary-longer-term">'''Full term:''' Global Environment Facility (GEF)</div>

<div class="glossary-definition">'''Definition:''' The Global Environment Facility, established in 1991, helps developing countries fund projects and programmes that protect the global environment. GEF grants support projects related to biodiversity, climate change, international waters, land degradation, the ozone (O3) layer, and persistent organic pollutants.</div>
</div>

<div class="glossary-entry">
<div id="Global_carbon_budget"></div>
=== <span class="glossary-term">Global carbon budget</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI; WGIII</div>

<div class="glossary-definition">'''Definition:''' An assessment of carbon cycle sources and sinks on a global level, through the synthesis of evidence for fossil-fuel and cement emissions, landuse change emissions, ocean and land CO2 sinks, and the resulting atmospheric CO2 growth rate.</div>
</div>

<div class="glossary-entry">
<div id="Global_change"></div>
=== <span class="glossary-term">Global change</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGII</div>

<div class="glossary-definition">'''Definition:''' A generic term to describe global scale changes in systems, including the climate system, ecosystems and social-ecological systems.</div>
</div>

<div class="glossary-entry">
<div id="Global_dimming"></div>
=== <span class="glossary-term">Global dimming</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI</div>

<div class="glossary-definition">'''Definition:''' Global dimming refers to the observed widespread reduction in the amount of solar radiation received at the Earth’s surface from the 1950s to the 1980s, with an increase in anthropogenic aerosol emissions appearing to have contributed. This was followed by a partial recovery since the 1990s (‘brightening’), particularly in industrialized areas, coincident with a reduction in anthropogenic aerosol emissions.</div>
</div>

<div class="glossary-entry">
<div id="Global_energy_budget"></div>
=== <span class="glossary-term">Global energy budget</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI</div>

<div class="glossary-definition">'''Definition:''' For a given time period, the global energy budget expresses the balance between change in the global energy inventory, the time-integrated effective radiative forcing and time-integrated radiative response of the climate system. Typical units: Joules.</div>
</div>

<div class="glossary-entry">
<div id="Global_energy_inventory"></div>
=== <span class="glossary-term">Global energy inventory</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI</div>

<div class="glossary-definition">'''Definition:''' quantifies the excess energy absorbed or lost by the Earth system (ocean, land, atmosphere and cryosphere), mostly in the form of heat, associated with radiative forcing of the climate. Typical units: Joules.</div>
</div>

<div class="glossary-entry">
<div id="Global_mean_sea_level_change"></div>
=== <span class="glossary-term">Global mean sea level change</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI; WGII</div>

<div class="glossary-longer-term">'''Full term:''' Global mean sea level (GMSL) change</div>

<div class="glossary-definition">'''Definition:''' The increase or decrease in the volume of the ocean divided by the ocean surface area. It is the sum of changes in ocean density through temperature changes (global mean thermosteric sea level change) and changes in the ocean mass as a result of changes in the cryosphere or land water storage (barystatic sea level change).</div>
</div>

<div class="glossary-entry">
<div id="Global_mean_surface_air_temperature"></div>
=== <span class="glossary-term">Global mean surface air temperature</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI; WGII; WGIII</div>

<div class="glossary-longer-term">'''Full term:''' Global mean surface air temperature (GSAT)</div>

<div class="glossary-definition">'''Definition:''' Global average of near-surface air temperatures over land, oceans and sea ice. Changes in GSAT are often used as a measure of global temperature change in climate models.</div>
</div>

<div class="glossary-entry">
<div id="Global_mean_surface_temperature"></div>
=== <span class="glossary-term">Global mean surface temperature</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI; WGII; WGIII</div>

<div class="glossary-longer-term">'''Full term:''' Global mean surface temperature (GMST)</div>

<div class="glossary-definition">'''Definition:''' Estimated global average of near-surface air temperatures over land and sea ice, and sea surface temperature (SST) over ice-free ocean regions, with changes normally expressed as departures from a value over a specified reference period.</div>
</div>

<div class="glossary-entry">
<div id="Global_monsoon"></div>
=== <span class="glossary-term">Global monsoon</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI; WGII</div>

<div class="glossary-definition">'''Definition:''' The global monsoon (GM) is a global-scale solstitial mode that dominates the annual variation of tropical and sub-tropical precipitation and circulation. The GM domain is defined as the area where the annual range of precipitation (local summer minus winter mean precipitation rate) is greater than 2.5 mm day -1, following on from the definition as in Kitoh et al. (2013). Further details on how the GM is defined, used and related to regional monsoons throughout the Report are provided by WGI AR6 Annex V (IPCC 2021b).</div>
</div>

<div class="glossary-entry">
<div id="Global_warming"></div>
=== <span class="glossary-term">Global warming</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI; WGII; WGIII</div>

<div class="glossary-definition">'''Definition:''' Global warming refers to the increase in global surface temperature relative to a baseline reference period, averaging over a period sufficient to remove interannual variations (e.g., 20 or 30 years). A common choice for the baseline is 1850–1900 (the earliest period of reliable observations with sufficient geographic coverage), with more modern baselines used depending upon the application.</div>
</div>

<div class="glossary-entry">
<div id="Global_warming_potential"></div>
=== <span class="glossary-term">Global warming potential</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI; WGIII</div>

<div class="glossary-longer-term">'''Full term:''' Global warming potential (GWP)</div>

<div class="glossary-definition">'''Definition:''' An index measuring the radiative forcing following an emission of a unit mass of a given substance, accumulated over a chosen time horizon, relative to that of the reference substance, carbon dioxide (CO2). The GWP thus represents the combined effect of the differing times these substances remain in the atmosphere and their effectiveness in causing radiative forcing.</div>
</div>

<div class="glossary-entry">
<div id="Governance"></div>
=== <span class="glossary-term">Governance</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGII; WGIII</div>

<div class="glossary-definition">'''Definition:''' The structures, processes and actions through which private and public actors interact to address societal goals. This includes formal and informal institutions and the associated norms, rules, laws and procedures for deciding, managing, implementing and monitoring policies and measures at any geographic or political scale, from global to local.</div>
</div>

<div class="glossary-entry">
<div id="Governance_capacity"></div>
=== <span class="glossary-term">Governance capacity</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGII; WGIII</div>

<div class="glossary-definition">'''Definition:''' The ability of governance institutions, leaders, and non-state and civil society to plan, coordinate, fund, implement, evaluate and adjust policies and measures over the short, medium and long term, adjusting for uncertainty, rapid change and wide-ranging impacts and multiple actors and demands.</div>
</div>

<div class="glossary-entry">
<div id="Gravitational,_rotational_and_deformational_effects"></div>
=== <span class="glossary-term">Gravitational, rotational and deformational effects</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI</div>

<div class="glossary-longer-term">'''Full term:''' Gravitational, rotational and deformational (GRD) effects</div>

<div class="glossary-definition">'''Definition:''' Changes in Earth gravity, Earth rotation and viscoelastic solid Earth deformation (GRD) result from the redistribution of mass between terrestrial ice and water reservoirs and the ocean. Contemporary terrestrial mass loss leads to elastic solid Earth uplift and a nearby relative sea level fall (for a single source of terrestrial mass loss this is within ~2000 km, for multiple sources the distance depends on the interaction of the different relative sea level patterns). Farther away (more than ~7000 km for a single source of terrestrial mass loss), relative sea level rises more than the global average, due (to first order) to gravitational effects. Earth deformation associated with adding water to the oceans and a shift of the Earth’s rotation axis towards the source of terrestrial mass loss leads to second-order effects that increase spatial variability of the pattern globally. GRD effects due to the redistribution of ocean water within the ocean itself are referred to as self-attraction and loading effects.</div>
</div>

<div class="glossary-entry">
<div id="Gravity_Recovery_and_Climate_Experiment"></div>
=== <span class="glossary-term">Gravity Recovery and Climate Experiment</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI</div>

<div class="glossary-longer-term">'''Full term:''' Gravity Recovery and Climate Experiment (GRACE)</div>

<div class="glossary-definition">'''Definition:''' A pair of satellites that measured the Earth’s gravity field anomalies from 2002 to 2017. These fields have been used, among other things, to study mass changes of the polar ice sheets and glaciers.</div>
</div>

<div class="glossary-entry">
<div id="Grazing_land"></div>
=== <span class="glossary-term">Grazing land</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGIII</div>

<div class="glossary-definition">'''Definition:''' The sum of rangelands and pastures not considered as cropland, and subject to livestock grazing or hay production. It includes a wide range of ecosystems, for example, systems with vegetation that fall below the threshold used in the forest land category, silvo-pastoral systems, as well as natural, managed grasslands and semi-deserts.</div>
</div>

<div class="glossary-entry">
<div id="Green_Climate_Fund"></div>
=== <span class="glossary-term">Green Climate Fund</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGII; WGIII</div>

<div class="glossary-longer-term">'''Full term:''' Green Climate Fund (GCF)</div>

<div class="glossary-definition">'''Definition:''' The Green Climate Fund was established by the 16th Session of the Conference of the Parties (COP) in 2010 as an operating entity of the financial mechanism of the United Nations Framework Convention on Climate Change (UNFCCC), in accordance with Article 11 of the Convention, to support projects, programmes and policies and other activities in developing country Parties. The Fund is governed by a board and will receive guidance from the COP.</div>
</div>

<div class="glossary-entry">
<div id="Green_infrastructure"></div>
=== <span class="glossary-term">Green infrastructure</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGII; WGIII</div>

<div class="glossary-definition">'''Definition:''' The strategically planned interconnected set of natural and constructed ecological systems, green spaces and other landscape features that can provide functions and services including air and water purification, temperature management, floodwater management and coastal defence often with co-benefits for human and ecological well-being. Green infrastructure includes planted and remnant native vegetation, soils, wetlands, parks and green open spaces, as well as building and street-level design interventions that incorporate vegetation (Culwick and Bobbins, 2016).</div>
</div>

<div class="glossary-entry">
<div id="Greenhouse_effect"></div>
=== <span class="glossary-term">Greenhouse effect</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI</div>

<div class="glossary-definition">'''Definition:''' The infrared radiative effect of all infrared-absorbing constituents in the atmosphere. Greenhouse gases (GHGs), clouds, and some aerosols absorb terrestrial radiation emitted by the Earth’s surface and elsewhere in the atmosphere. These substances emit infrared radiation in all directions, but, everything else being equal, the net amount emitted to space is normally less than would have been emitted in the absence of these absorbers because of the decline of temperature with altitude in the troposphere and the consequent weakening of emission. An increase in the concentration of GHGs increases the magnitude of this effect; the difference is sometimes called the enhanced greenhouse effect. The change in a GHG concentration because of anthropogenic emissions contributes to an instantaneous radiative forcing. Earth’s surface temperature and troposphere warm in response to this forcing, gradually restoring the radiative balance at the top of the atmosphere.</div>
</div>

<div class="glossary-entry">
<div id="Greenhouse_gas_emission_metric"></div>
=== <span class="glossary-term">Greenhouse gas emission metric</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI; WGIII</div>

<div class="glossary-definition">'''Definition:''' A simplified relationship used to quantify the effect of emitting a unit mass of a given greenhouse gas (GHG) on a specified key measure of climate change. A relative GHG emission metric expresses the effect from one gas relative to the effect of emitting a unit mass of a reference GHG on the same measure of climate change. There are multiple emission metrics, and the most appropriate metric depends on the application. GHG emission metrics may differ with respect to: (i) the key measure of climate change they consider; (ii) whether they consider climate outcomes for a specified point in time or integrated over a specified time horizon; (iii) the time horizon over which the metric is applied; (iv) whether they apply to a single emission pulse, emissions sustained over a period of time, or a combination of both; and (v) whether they consider the climate effect from an emission compared to the absence of that emission or compared to a reference emissions level or climate state. [Note:Most relative GHG emission metrics (such as the g lobal warming potential (GWP), global temperature change potential (GTP), global damage potential, and GWP*), use carbon dioxide (CO 2) as the reference gas. Emissions of non-CO2 gases, when expressed using such metrics, are often referred to as ‘carbon dioxide equivalent’ emissions. A metric that establishes equivalence regarding one key measure of the climate system response to emissions does not imply equivalence regarding other key measures. The choice of a metric, including its time horizon, should reflect the policy objectives for which the metric is applied.]</div>
</div>

<div class="glossary-entry">
<div id="Greenhouse_gas_neutrality"></div>
=== <span class="glossary-term">Greenhouse gas neutrality</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI; WGIII</div>

<div class="glossary-definition">'''Definition:''' Condition in which metric-weighted anthropogenic greenhouse gas (GHG) emissions associated with a subject are balanced by metric-weighted anthropogenic GHG removals. The subject can be an entity such as a country, an organisation, a district or a commodity, or an activity such as a service or an event. GHG neutrality is often assessed over the lifecycle, including indirect (‘scope 3’) emissions, but can also be limited to the emissions and removals, over a specified period, for which the subject has direct control, as determined by the relevant scheme. The quantification of GHG emissions and removals depends on the GHG emission metric chosen to compare emissions and removals of different gases, as well as the time horizon chosen for that metric [Note 1: Greenhouse gas neutrality and net zero greenhouse gas emissions are overlapping concepts. The concepts can be applied at global or sub-global scales (e.g., regional, national and sub-national). At a global scale, the terms greenhouse gas neutrality and net zero greenhouse gas emissions are equivalent. At sub-global scales, net zero GHG emissions is generally applied to emissions and removals under direct control or territorial responsibility of the reporting entity, while GHG neutrality generally includes emissions and removals within and beyond the direct control or territorial responsibility of the reporting entity. Accounting rules specified by GHG programmes or schemes can have a significant influence on the quantification of relevant emissions and removals. Note 2: Under the Paris Rulebook (Decision 18/CMA.1, annex, paragraph 37), parties have agreed to use GWP100 values from the IPCC AR5 or GWP100 values from a subsequent IPCC Assessment Report to report aggregate emissions and removals of GHGs. In addition, parties may use other metrics to report supplemental information on aggregate emissions and removals of GHGs. Note 3: In some cases, achieving greenhouse gas neutrality may rely on the supplementary use of offsets to balance emissions that remain after actions by the reporting entity are taken into account.]</div>
</div>

<div class="glossary-entry">
<div id="Greenhouse_gases"></div>
=== <span class="glossary-term">Greenhouse gases</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI; WGII; WGIII</div>

<div class="glossary-longer-term">'''Full term:''' Greenhouse gases (GHGs)</div>

<div class="glossary-definition">'''Definition:''' Gaseous constituents of the atmosphere, both natural and anthropogenic, that absorb and emit radiation at specific wavelengths within the spectrum of radiation emitted by the Earth’s surface, by the atmosphere itself, and by clouds. This property causes the greenhouse effect. Water vapour (H 2 O), 2) carbon dioxide (CO, 2 O) nitrous oxide (N, 4) methane (CH and 3) ozone (O are the primary GHGs in the Earth’s atmosphere. Human-made GHGs include 6), sulphur hexafluoride (SF hydrofluorocarbons (HFCs), chlorofluorocarbons (CFCs) and perfluorocarbons (PFCs); several of these are also O 3 -depleting (and are regulated under the Montreal Protocol).</div>
</div>

<div class="glossary-entry">
<div id="Greenland_Ice_Sheet"></div>
=== <span class="glossary-term">Greenland Ice Sheet</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI</div>

<div class="glossary-longer-term">'''Full term:''' Greenland Ice Sheet (GrIS)</div>

<div class="glossary-definition">'''Definition:''' There are only two ice sheets in the modern world, one on Greenland and one on Antarctica. The latter is divided into the East Antarctic Ice Sheet (EAIS), the West Antarctic Ice Sheet (WAIS) and the Antarctic Peninsula Ice Sheet. During glacial periods, there were other ice sheets.</div>
</div>

<div class="glossary-entry">
<div id="Grey_infrastructure"></div>
=== <span class="glossary-term">Grey infrastructure</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGII; WGIII</div>

<div class="glossary-definition">'''Definition:''' Engineered physical components and networks of pipes, wires, tracks and roads that underpin energy, transport, communications (including digital), built form, water and sanitation and solid waste management systems.</div>
</div>

<div class="glossary-entry">
<div id="Gross_domestic_product"></div>
=== <span class="glossary-term">Gross domestic product</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGII; WGIII</div>

<div class="glossary-longer-term">'''Full term:''' Gross domestic product (GDP)</div>

<div class="glossary-definition">'''Definition:''' The sum of gross value added, at purchasers’ prices, by all resident and non-resident producers in the economy, plus any taxes and minus any subsidies not included in the value of the products in a country or a geographic region for a given period, normally one year. GDP is calculated without deducting for depreciation of fabricated assets or depletion and degradation of natural resources.</div>
</div>

<div class="glossary-entry">
<div id="Gross_primary_production"></div>
=== <span class="glossary-term">Gross primary production</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI</div>

<div class="glossary-longer-term">'''Full term:''' Gross primary production (GPP)</div>

<div class="glossary-definition">'''Definition:''' The total amount of carbon fixed by photosynthesis over a specified time period.</div>
</div>

<div class="glossary-entry">
<div id="Ground-level_ozone"></div>
=== <span class="glossary-term">Ground-level ozone</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI</div>

<div class="glossary-definition">'''Definition:''' Atmospheric ozone (O3) is formed naturally or from human-emitted precursors near Earth’s surface, thus affecting human health, agriculture and ecosystems. Ozone is a greenhouse gas (GHG), but ground-level ozone, unlike stratospheric ozone, also directly affects organisms at the surface. Ground-level ozone is sometimes referred to as tropospheric ozone, although much of the troposphere is well above the surface and thus does not directly expose organisms at the surface.</div>
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=== <span class="glossary-term">Grounding line</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI</div>

<div class="glossary-definition">'''Definition:''' The junction between a glacier or ice sheet and an ice shelf; the place where ice starts to float. This junction normally occurs over a zone, rather than at a line.</div>
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=== <span class="glossary-term">Groundwater recharge</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGII</div>

<div class="glossary-definition">'''Definition:''' The process by which external water is added to the zone of saturation of an aquifer, either directly into a geologic formation that traps the water or indirectly by way of another formation.</div>
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<div id="Gyre"></div>
=== <span class="glossary-term">Gyre</span> ===

<div class="glossary-working-groups">'''Working Groups:''' WGI</div>

<div class="glossary-definition">'''Definition:''' Basin-scale ocean horizontal circulation pattern with slow flow circulating around the ocean basin, closed by a strong and narrow (100 to 200 km wide) boundary current on the western side. The subtropical gyres in each ocean are associated with high pressure in the centre of the gyres; the subpolar gyres are associated with low pressure.</div>
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