Editing IPCC:AR6/Data/Glossary (section)

== M ==

<div class="glossary-entry">
<div id="MaddenJulian_Oscillation"></div>
=== <span class="glossary-term">Madden–Julian Oscillation</span> ===

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

<div class="glossary-longer-term">'''Full term:''' Madden–Julian Oscillation (MJO)</div>

<div class="glossary-definition">'''Definition:''' The largest mode of tropical atmospheric intra-seasonal variability with typical periods ranging from 20 to 90 days. The MJO corresponds to planetary-scale disturbances of pressure, wind and deep convection moving predominantly eastward along the equator. As it progresses, the MJO is associated with the temporal alternation of large-scale enhanced and suppressed rainfall, with maximum loading over the Indian and western Pacific oceans, although influences of the MJO can be tracked over the Atlantic/Africa in dynamical fields. See Section AIV.2.8 in Annex IV of the AR6 WGI report.</div>
</div>

<div class="glossary-entry">
<div id="Maladaptive_actions"></div>
=== <span class="glossary-term">Maladaptive actions</span> ===

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

<div class="glossary-longer-term">'''Full term:''' Maladaptive actions (Maladaptation)</div>

<div class="glossary-definition">'''Definition:''' Actions that may lead to increased risk of adverse climate-related outcomes, including via increased greenhouse gas (GHG) emissions, increased or shifted vulnerability to climate change, more inequitable outcomes, or diminished welfare, now or in the future. Most often, maladaptation is an unintended consequence.</div>
</div>

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

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

<div class="glossary-definition">'''Definition:''' Deficiencies, excesses, or imbalances in a person’s intake of energy and/or nutrients. The term malnutrition addresses three broad groups of conditions: undernutrition, which includes wasting (low weight-for-height), stunting (low height-for-age) and underweight (low weight-for-age); micronutrient-related malnutrition, which includes micronutrient deficiencies (a lack of important vitamins and minerals) or micronutrient excess; and overweight, obesity and diet-related non-communicable diseases (such as heart disease, stroke, diabetes and some cancers) (WHO, 2018). Micronutrient deficiencies are sometimes termed ‘hidden hunger’ to emphasise that people can be malnourished in the sense of deficient without being deficient in calories. Hidden hunger can apply even where people are obese.</div>
</div>

<div class="glossary-entry">
<div id="Managed_forest"></div>
=== <span class="glossary-term">Managed forest</span> ===

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

<div class="glossary-definition">'''Definition:''' Forests subject to human interventions (notably silvicultural management such as planting, pruning, thinning), timber and fuelwood harvest, protection (fire suppression, insect suppression) and management for amenity values or conservation, with defined geographical boundaries (Ogle et al., 2018). [Note: For a discussion of the term ‘forest’ in the context of National GHG inventories, see the 2006 IPCC Guidelines for National GHG Inventories (IPCC 2006).]</div>
</div>

<div class="glossary-entry">
<div id="Managed_grassland"></div>
=== <span class="glossary-term">Managed grassland</span> ===

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

<div class="glossary-definition">'''Definition:''' Grasslands on which human interventions are carried out, such as grazing domestic livestock or hay removal.</div>
</div>

<div class="glossary-entry">
<div id="Managed_land"></div>
=== <span class="glossary-term">Managed land</span> ===

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

<div class="glossary-definition">'''Definition:''' In the context of national greenhouse gas (GHG) inventories under the United Nations Framework Convention on Climate Change (UNFCCC), the 2006 IPCC Guidelines for National GHG Inventories (IPCC, 2006) defines managed land ‘where human interventions and practices have been applied to perform production, ecological or social functions’. IPCC (2006) defines anthropogenic GHG emissions and removals in the LULUCF sector as all those occurring on ‘managed land’. The key rationale for this approach is that the preponderance of anthropogenic effects occurs on managed lands. [Note: More details can be found in IPCC 2006 Guidelines for National GHG Inventories, Volume 4, Chapter 1.]</div>
</div>

<div class="glossary-entry">
<div id="Marine-based_ice_sheet"></div>
=== <span class="glossary-term">Marine-based ice sheet</span> ===

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

<div class="glossary-definition">'''Definition:''' An ice sheet containing a substantial region that rests on a bed lying below sea level and whose perimeter is in contact with the ocean. The best known example is the West Antarctic Ice Sheet.</div>
</div>

<div class="glossary-entry">
<div id="Marine_cloud_brightening"></div>
=== <span class="glossary-term">Marine cloud brightening</span> ===

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

<div class="glossary-longer-term">'''Full term:''' Marine cloud brightening (MCB)</div>

<div class="glossary-definition">'''Definition:''' One of several solar radiation modification (SRM) approaches to increase the planetary albedo. In this approach, it is proposed to inject sea salt aerosols into persistent marine low clouds. This is expected to increase the cloud droplet concentration of these clouds and their reflectivity.</div>
</div>

<div class="glossary-entry">
<div id="Marine_heatwave"></div>
=== <span class="glossary-term">Marine heatwave</span> ===

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

<div class="glossary-definition">'''Definition:''' A period during which water temperature is abnormally warm for the time of the year relative to historical temperatures, with that extreme warmth persisting for days to months. The phenomenon can manifest in any place in the ocean and at scales of up to thousands of kilometres.</div>
</div>

<div class="glossary-entry">
<div id="Marine_ice_cliff_instability"></div>
=== <span class="glossary-term">Marine ice cliff instability</span> ===

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

<div class="glossary-longer-term">'''Full term:''' Marine ice cliff instability (MICI)</div>

<div class="glossary-definition">'''Definition:''' A hypothetical mechanism of an ice cliff failure. In case a marine-terminated ice sheet loses its buttressing ice shelf, an ice cliff can be exposed. If the exposed ice cliff is tall enough (about 800 m of the total height, or about 100 m of the above-water part), the stresses at the cliff face exceed the strength of the ice, and the cliff fails structurally in repeated calving events.</div>
</div>

<div class="glossary-entry">
<div id="Marine_ice_sheet_instability"></div>
=== <span class="glossary-term">Marine ice sheet instability</span> ===

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

<div class="glossary-longer-term">'''Full term:''' Marine ice sheet instability (MISI)</div>

<div class="glossary-definition">'''Definition:''' A mechanism of irreversible (on the decadal to centennial time scale) retreat of a grounding line for the marine-terminating glaciers, in case the glacier bed slopes towards the ice sheet interior.</div>
</div>

<div class="glossary-entry">
<div id="Marine_isotope_stage"></div>
=== <span class="glossary-term">Marine isotope stage</span> ===

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

<div class="glossary-longer-term">'''Full term:''' Marine isotope stage (MIS)</div>

<div class="glossary-definition">'''Definition:''' Geological periods of alternating glacial and interglacial conditions, each typically lasting tens of thousands of years as inferred from the oxygen isotope composition of microfossils from deep sea sediment cores. MIS numbers increase back in time from the present, which is MIS 1. Even-number MISs coincide with glacial periods, and odd-numbered MISs are interglacials.</div>
</div>

<div class="glossary-entry">
<div id="Market_failure"></div>
=== <span class="glossary-term">Market failure</span> ===

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

<div class="glossary-definition">'''Definition:''' When private decisions are based on market prices that do not reflect the real scarcity of goods and services but rather reflect market distortions, they do not generate an efficient allocation of resources but cause welfare losses. A market distortion is any event in which a market reaches a market clearing price that is substantially different from the price that a market would achieve while operating under conditions of perfect competition and state enforcement of legal contracts and the ownership of private property. Examples of factors causing market prices to deviate from real economic scarcity are environmental externalities, public goods, monopoly power, information asymmetry, transaction costs, and non-rational behaviour.</div>
</div>

<div class="glossary-entry">
<div id="Mass_balance_budget"></div>
=== <span class="glossary-term">Mass balance/budget</span> ===

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

<div class="glossary-longer-term">'''Full term:''' Mass balance/budget (of glaciers or ice sheets)</div>

<div class="glossary-definition">'''Definition:''' Difference between the mass input (accumulation) and the mass loss (ablation) of an ice body (e.g., a glacier or ice sheet) over a stated time period, which is often a year or a season. Surface mass balance refers to the difference between surface accumulation and surface ablation.</div>
</div>

<div class="glossary-entry">
<div id="Material_substitution"></div>
=== <span class="glossary-term">Material substitution</span> ===

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

<div class="glossary-definition">'''Definition:''' Replacement of one material (including an energy carrier used as a feedstock) by another, due to scarcity, price, technological change, or because of lower environmental impacts or greenhouse gas emissions.</div>
</div>

<div class="glossary-entry">
<div id="Mean_sea_level"></div>
=== <span class="glossary-term">Mean sea level</span> ===

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

<div class="glossary-definition">'''Definition:''' The surface level of the ocean at a particular point averaged over an extended period of time such as a month or year. Mean sea level is often used as a national datum to which heights on land are referred.</div>
</div>

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

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

<div class="glossary-definition">'''Definition:''' ‘Processes of data collection over time, providing basic datasets, including associated accuracy and precision, for the range of relevant variables. Possible data sources are field measurements, field observations, detection through remote sensing and interviews’ (UN-REDD, 2009).</div>
</div>

<div class="glossary-entry">
<div id="Measurement,_Reporting_and_Verification"></div>
=== <span class="glossary-term">Measurement, Reporting and Verification</span> ===

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

<div class="glossary-longer-term">'''Full term:''' Measurement, Reporting and Verification (MRV)</div>

<div class="glossary-definition">'''Definition:''' Measurement ‘Processes of data collection over time, providing basic datasets, including associated accuracy and precision, for the range of relevant variables. Possible data sources are field measurements, field observations, detection through remote sensing and interviews’ (UN-REDD, 2009). Reporting ‘The process of formal reporting of assessment results to the UNFCCC, according to predetermined formats and according to established standards, especially the Intergovernmental Panel on Climate Change (IPCC) Guidelines and GPG (Good Practice Guidance)’ (UN-REDD, 2009). Verification ‘The process of formal verification of reports, for example, the established approach to verify national communications and national inventory reports to the UNFCCC’ (UN-REDD, 2009).</div>
</div>

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

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

<div class="glossary-definition">'''Definition:''' An urban agglomeration with 10 million inhabitants or more (United Nations, Department of Economic and Social Affairs, Population Division (2019).</div>
</div>

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

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

<div class="glossary-definition">'''Definition:''' A very lengthy and pervasive drought, lasting much longer than normal, usually a decade or more.</div>
</div>

<div class="glossary-entry">
<div id="Meltwater_Pulse_1A"></div>
=== <span class="glossary-term">Meltwater Pulse 1A</span> ===

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

<div class="glossary-longer-term">'''Full term:''' Meltwater Pulse 1A (MWP-1A)</div>

<div class="glossary-definition">'''Definition:''' A particular interval of rapid global sea level rise between about 14,700 and 14,300 years ago, associated with the end of the last ice age and attributed to freshwater flux to the ocean from accelerated melting of ice sheets and glaciers. First defined based on oxygen isotope data (Duplessy et al., 1981), and later shown to be reflected by high rates of sea level rise (Fairbanks, 1989).</div>
</div>

<div class="glossary-entry">
<div id="Mental_health"></div>
=== <span class="glossary-term">Mental health</span> ===

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

<div class="glossary-definition">'''Definition:''' The state of well-being in which an individual realises his or her own abilities, can cope with the normal stresses of life, can work productively and is able to contribute to his or her community.</div>
</div>

<div class="glossary-entry">
<div id="Meridional_overturning_circulation"></div>
=== <span class="glossary-term">Meridional overturning circulation</span> ===

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

<div class="glossary-longer-term">'''Full term:''' Meridional overturning circulation (MOC)</div>

<div class="glossary-definition">'''Definition:''' Meridional (north–south) overturning circulation in the ocean quantified by zonal (east–west) sums of mass transports in depth or density layers. In the North Atlantic, away from the subpolar regions, the MOC (which is in principle an observable quantity) is often identified with the thermohaline circulation (THC), which is a conceptual and incomplete interpretation. The MOC is also driven by wind, and can also include shallower overturning cells such as occur in the upper ocean in the tropics and subtropics, in which warm (light) waters moving poleward are transformed to slightly denser waters and subducted equatorward at deeper levels.</div>
</div>

<div class="glossary-entry">
<div id="Meteorological_drought"></div>
=== <span class="glossary-term">Meteorological drought</span> ===

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

<div class="glossary-definition">'''Definition:''' A period with an abnormal precipitation deficit.</div>
</div>

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

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

<div class="glossary-longer-term">'''Full term:''' Methane (CH4)</div>

<div class="glossary-definition">'''Definition:''' The greenhouse gas methane is the major component of natural gas and associated with all hydrocarbon fuels. Significant anthropogenic emissions also occur as a result of animal husbandry and paddy rice production. Methane is also produced naturally where organic matter decays under anaerobic conditions, such as in wetlands. Under future global warming, there is potential for increased methane emissions from thawing permafrost, wetlands and sub-sea gas hydrates.</div>
</div>

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

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

<div class="glossary-definition">'''Definition:''' A consistent measurement of a characteristic of an object or activity that is otherwise difficult to quantify. Within the context of the evaluation of climate models, this is a quantitative measure of agreement between a simulated and an observed quantity which can be used to assess the performance of individual models.</div>
</div>

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

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

<div class="glossary-definition">'''Definition:''' Local climate at or near the Earth’s surface.</div>
</div>

<div class="glossary-entry">
<div id="Microwave_sounding_unit"></div>
=== <span class="glossary-term">Microwave sounding unit</span> ===

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

<div class="glossary-longer-term">'''Full term:''' Microwave sounding unit (MSU)</div>

<div class="glossary-definition">'''Definition:''' A microwave sounder on U.S. National Oceanic and Atmospheric Administration (NOAA) polar orbiter satellites that estimates the temperature of thick layers of the atmosphere by measuring the thermal emission of oxygen molecules from a complex of emission lines near 60 GHz. A series of nine MSUs began making this kind of measurement in late 1978. Beginning in mid-1998, a follow-on series of instruments, the Advanced Microwave Sounding Units (AMSUs), began operation.</div>
</div>

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

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

<div class="glossary-definition">'''Definition:''' Any person who is moving or has moved across an international border or within a State away from his/her habitual place of residence, regardless of (1) the person’s legal status; (2) whether the movement is voluntary or involuntary; (3) what the causes for the movement are; or (4) what the length of the stay is (IOM, 2018).</div>
</div>

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

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

<div class="glossary-longer-term">'''Full term:''' Migration (of humans)</div>

<div class="glossary-definition">'''Definition:''' Movement of a person or a group of persons, either across an international border, or within a State. It is a population movement, encompassing any kind of movement of people, whatever its length, composition and causes; it includes migration of refugees, displaced persons, economic migrants, and persons moving for other purposes, including family reunification (IOM, 2018).</div>
</div>

<div class="glossary-entry">
<div id="Mineralization_Remineralization"></div>
=== <span class="glossary-term">Mineralization/Remineralization</span> ===

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

<div class="glossary-definition">'''Definition:''' The conversion of an element from its organic form to an inorganic form as a result of microbial decomposition. In nitrogen mineralization, organic nitrogen from decaying plant and animal residues (proteins, nucleic acids, amino sugars and urea) is converted to ammonia (NH 3) and ammonium (NH 4 +) by biological activity.</div>
</div>

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

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

<div class="glossary-longer-term">'''Full term:''' Mitigation (of climate change)</div>

<div class="glossary-definition">'''Definition:''' A human intervention to reduce emissions or enhance the sinks of greenhouse gases.</div>
</div>

<div class="glossary-entry">
<div id="Mitigation_measures"></div>
=== <span class="glossary-term">Mitigation measures</span> ===

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

<div class="glossary-definition">'''Definition:''' In climate policy, mitigation measures are technologies, processes or practices that contribute to mitigation, for example, renewable energy technologies, waste minimisation processes, and public transport commuting practices.</div>
</div>

<div class="glossary-entry">
<div id="Mitigation_option"></div>
=== <span class="glossary-term">Mitigation option</span> ===

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

<div class="glossary-definition">'''Definition:''' A technology or practice that reduces greenhouse gas (GHG) emissions or enhances sinks.</div>
</div>

<div class="glossary-entry">
<div id="Mitigation_pathways"></div>
=== <span class="glossary-term">Mitigation pathways</span> ===

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

<div class="glossary-definition">'''Definition:''' A temporal evolution of a set of mitigation scenario features, such as greenhouse gas (GHG) emissions and socio-economic development.</div>
</div>

<div class="glossary-entry">
<div id="Mitigation_potential"></div>
=== <span class="glossary-term">Mitigation potential</span> ===

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

<div class="glossary-definition">'''Definition:''' The quantity of net greenhouse gas emission reductions that can be achieved by a given mitigation option relative to specified emission baselines. [Note: Net greenhouse gas emission reduction is the sum of reduced emissions and/or enhanced sinks.]</div>
</div>

<div class="glossary-entry">
<div id="Mitigation_scenario"></div>
=== <span class="glossary-term">Mitigation scenario</span> ===

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

<div class="glossary-definition">'''Definition:''' A plausible description of the future that describes how the (studied) system responds to the implementation of mitigation policies and measures.</div>
</div>

<div class="glossary-entry">
<div id="Model_initialization"></div>
=== <span class="glossary-term">Model initialization</span> ===

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

<div class="glossary-definition">'''Definition:''' A climate prediction typically proceeds by integrating a climate model forward in time from an initial state that is intended to reflect the actual state of the climate system. Available observations of the climate system are assimilated into the model. Initialization is a complex process that is limited by available observations, observational errors and, depending on the procedure used, may be affected by uncertainty in the history of climate forcing. The initial conditions will contain errors that grow as the forecast progresses, thereby limiting the time period over which the forecast will be useful.</div>
</div>

<div class="glossary-entry">
<div id="Model_spread"></div>
=== <span class="glossary-term">Model spread</span> ===

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

<div class="glossary-definition">'''Definition:''' The range or spread in results from climate models, such as those assembled for Coupled Model Intercomparison Project Phase 6 (CMIP6). Does not necessarily provide an exhaustive and formal estimate of the uncertainty in feedbacks, forcing or projections even when expressed numerically, for example, by computing a standard deviation of the models’ responses. In order to quantify uncertainty, information from observations, physical constraints and expert judgement must be combined, using a statistical framework.</div>
</div>

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

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

<div class="glossary-definition">'''Definition:''' Structured imitations of a system’s attributes and mechanisms to mimic the appearance or functioning of systems, for example, the climate, the economy of a country, or a crop. Mathematical models assemble (many) variables and relations (often in a computer code) to simulate system functioning and performance for variations in parameters and inputs.</div>
</div>

<div class="glossary-entry">
<div id="Modes_of_climate_variability"></div>
=== <span class="glossary-term">Modes of climate variability</span> ===

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

<div class="glossary-definition">'''Definition:''' Recurrent space-time structures of natural variability of the climate system with intrinsic spatial patterns, seasonality and time scales. Modes can arise through the dynamical characteristics of the atmospheric circulation but also through coupling between the ocean and the atmosphere, with some interactions with land surfaces and sea ice. Many modes of variability are driven by internal climate processes and are a critical potential source of climate predictability on sub-seasonal to decadal time scales. See Annex IV of the AR6 WGI report.</div>
</div>

<div class="glossary-entry">
<div id="Mole_fraction_or_mixing_ratio"></div>
=== <span class="glossary-term">Mole fraction or mixing ratio</span> ===

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

<div class="glossary-definition">'''Definition:''' Mole fraction, or mixing ratio, is the ratio of the number of moles of a constituent in a given volume to the total number of moles of all constituents in that volume. It is usually reported for dry air. Typical values for well-mixed greenhouse gases are in the order of μmol mol –1 (parts per million: ppm), nmol mol –1 (parts per billion: ppb), and fmol mol –1 (parts per trillion: ppt). Mole fraction differs from volume mixing ratio, often expressed in ppmv, etc., by the corrections for non-ideality of gases. This correction is significant relative to measurement precision for many greenhouse gases (Schwartz and Warneck, 1995).</div>
</div>

<div class="glossary-entry">
<div id="Monitoring_and_evaluation"></div>
=== <span class="glossary-term">Monitoring and evaluation</span> ===

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

<div class="glossary-longer-term">'''Full term:''' Monitoring and evaluation (M&E)</div>

<div class="glossary-definition">'''Definition:''' Mechanisms put in place to respectively monitor and evaluate efforts to reduce greenhouse gas emissions and/or adapt to the impacts of climate change with the aim of systematically identifying, characterising and assessing progress over time.</div>
</div>

<div class="glossary-entry">
<div id="Montreal_Protocol"></div>
=== <span class="glossary-term">Montreal Protocol</span> ===

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

<div class="glossary-definition">'''Definition:''' The Montreal Protocol on Substances that Deplete the Ozone Layer was adopted in Montreal in 1987, and subsequently adjusted and amended (including London (1990), Copenhagen (1992), Vienna (1995), Montreal (1997), Beijing (1999) and Kigali(2016)). It controls the consumption and production of chlorine- and bromine-containing chemicals that destroy 3) stratospheric ozone (O, such as chlorofluorocarbons (CFCs), methyl chloroform, carbon tetrachloride and many others. Since the Kigali Amendment in 2016, hydrofluorocarbons (HFCs), which were used as alternatives to ozone-depleting substances (ODSs), have been targeted for a phase-down due to their climate effect as greenhouse gases (GHGs).</div>
</div>

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

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

<div class="glossary-definition">'''Definition:''' A mountain is a landform formed through plate tectonics that rises above its surrounding area, characterised by verticality and ruggedness such as gentle or steep sloping sides, sharp or rounded ridges and a high point called a peak or a summit. Mountain regions consist of mountains and mountain ranges as defined by ruggedness, intermontane valleys, plateaus and tablelands, and hills and hilly forelands, together forming a complex terrain. To delineate mountain regions, a combination of terrain characteristics is used, such as elevation above sea level, steepness of slope and relative relief or local elevational range. Three mountain characterisations using different combinations of the above criteria applied to digital elevation models have been developed to arrive at mountain area statistics, described and analysed in detail by Sayre et al. (2018), namely K1 (Kapos et al., 2000), K2 (Körner et al., 2011) and K3 (Karagulle et al., 2017).</div>
</div>

<div class="glossary-entry">
<div id="Multi-level_governance"></div>
=== <span class="glossary-term">Multi-level governance</span> ===

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

<div class="glossary-definition">'''Definition:''' The dispersion of governance across multiple levels of jurisdiction and decision-making, including, global, regional, national and local, as well as trans-regional and trans-national levels.</div>
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