Glossary

Melting and evaporation on glaciers and in snow fields.

An organism’s short- or long-term adaptation to changing climatic conditions.

Arctic Climate Impact Assessment.

Initiatives and measures intended to reduce the vulnerability of natural and human systems to actual or expected impacts of climate change.

The term “absorption” generally refers to the absorption of light.

In oceanography and meteorology, the term “advection” refers to the horizontal transport of properties via currents in the water or air.

Solid or liquid particles in the air.

Albedo is used to measure a given body’s reflectivity. The lighter it is, the higher its albedo.

A term used in geology and ecology to describe materials, geological objects or organisms from outside a given system or region.

Arctic Monitoring and Assessment Programme.

Submerged ice that is attached or anchored to the bottom of a body of water, regardless of how it was formed.

Negatively charged ions produced when an atom or molecule takes on additional electrons , so that it has more electrons than protons and therefore a negative overall charge. Examples include chloride (Cl-), sulphate (SO₄²-), bicarbonate (HCO₃^-) and bromide (Br^-).

Directional dependence of a substance’s property

Predominant atmospheric circulation pattern that reflects changes in the mean zonal westerly wind in the middle latitudes.

The Antarctic Circumpolar Current (ACC) is a ring-shaped, cold ocean current flowing about the Antarctic.

The Antarctic Convergence is a roughly 40-km-wide water zone in the Southern Ocean in which cold, northward-flowing currents sink below warmer, southward-flowing surface water.

Region of divergent ocean currents that encircle Antarctica and produce upwelling.

The wind system in the Southern Ocean describing the north-south shifting of the westerly winds, which drives the wind field from west to east in a circular motion and dominates large-scale atmospheric circulation in the middle and high latitudes of the Southern Hemisphere.

Represents the basis for preserving the Antarctic. The System reflects the shared desire to exclusively use the Antarctic for peaceful purposes for all time.

Direct and indirect influences on the environment, either caused or produced by human beings.

Emissions of greenhouse gases, their precursors, and aerosols in connection with human activities.

Archaeans are tiny, single-celled bacteria, and can be round, rod- or ribbon-shaped. Capable of surviving under harsh conditions, they are extremely frugal. Archaeans can be found in a variety of settings and there are numerous subspecies. They are one of the three major groups of organisms (the others being eukaryotes and bacteria) formed in the course of evolution.

polar region located at the northernmost part of Earth

“Arctic Oscillation (AO)” refers to the changes in atmospheric pressure differences near the surface between the Arctic and middle latitudes in the Northern Hemisphere.

The conversion of nutrients into bodily substances, chiefly in connection with the energy-consuming chemical reactions in metabolism.

The gaseous envelope surrounding the Earth.

Refers to the deposition of atmospheric substances.

The Southern and Northern Lights.

When something is still where it originated and was not transported (e.g. by a river).

How green plants and many microorganisms that only require inorganic substances to grow feed themselves.

Horizontal direction in a three-dimensional coordinate system

The Beaufort Gyre is an anti-cyclonal, clockwise-spinning ice drift in the Beaufort Sea which transports sea ice from the northern coasts of Greenland, Canada and Alaska to the Central Arctic.

The community of organisms living on and in the bottom of a body of water (benthic zone).

The biotic community of all plants and animals in a given habitat.

Biological diversity or biodiversity refers to the variety of species, to genetic peculiarities within species, and to the variety of biotic communities.

Bioluminescence refers to lifeforms that naturally produce light.

Biomass is the entirety of organic material produced by plants or animals.

A biome is a large but discrete biogeographical unit, together with its characteristic flora and fauna.

The entirety of the Earth that is home to lifeforms.

Biota can be understood as the collective term for all lifeforms in a given ecosystem, including bacteria, plants, fungi and animals.

Federal Ministry for Economic Affairs and Climate Action.

Models that reflect the reality by aggregating the characteristics of certain activities and processes.

Collection of small ice fragments with a max. width of 2 m (small floes); the debris of other forms of ice.

A general term for the formation of cracks in the ice and the subsequent drifting apart of the fragments.

Highly concentrated saltwater. Learn more about sea ice desalination here.

Small pockets or channels in the sea ice in which highly concentrated brine accumulates.

The part of a hummock that extends underwater.

Autonomous measuring systems.

Chemical symbol for carbon.

When a mass of ice breaks off from a wall of ice, ice front (ice-shelf edge) or iceberg.

The separation of ice crystals in freshwater and brackish-water ice into individual crystals (“candles”) as the result of different melting processes between the crystals, caused by the absorption of sunlight.

Process involving the capture of CO₂ from industrial and energy-related sources, its transport to a storage facility, and its long-term isolation from the atmosphere.

In all four spheres of the environment, the element carbon occurs in the form of various compounds.

A naturally occurring gas, but also a by-product of burning fossil fuels and biomass, of land-use changes and industrial processes.

Ratio of CO₂ emissions to gross domestic product (GDP).

Positively charged ions produced when an element or an anion loses electrons until its overall charge is positive, i.e., until it has more protons than electrons. Examples include sodium (Na⁺), magnesium (Mg²⁺), calcium (Ca²⁺), potassium (K⁺) and strontium (Sr²⁺).

Carbon capture and storage.

Clean Development Mechanism.

The abbreviation for chlorofluorocarbons.

Chemical formula for the compound methane.

Specialised organelles found in the cells of photosynthetically active organisms, e.g. in the cells of plants, algae and certain bacteria. They convert light energy into chemical energy through photosynthesis.

The currents flowing around the polar regions of both hemispheres are referred to as the Circumpolar Currents.

Climate in the stricter sense is defined as the mean status of the atmosphere in a given place or region over an extended timeframe.

A climate archive offers insights into the Earth’s past climate / climate history. Accordingly, anything that stores information on past climatic conditions can be considered a climate archive.

Climate change refers to any change in the climate over time that can be identified by a change in the mean value or in the variation range of its properties.

Refers to factors that affect various components of the climate.

Interaction mechanism between processes in the climate system.

Due to climate inertia, the climate will continue to change even long after the CO₂ concentration stabilises. Climate models indicate that the surface air temperature will continue to rise for at least a further century.

A numerical representation of the climate system based on the physical, chemical and biological properties of its components, their interactions and feedbacks, and which considers all or certain known properties of the system.

Estimate of how the climate will develop in the future on a seasonal, multi-year or longer-term time scale. Outcomes are presented as probabilities.

A projection of how the climate system would react to a given emission or concentration scenario for greenhouse gases, aerosols or radiative forcing scenarios, frequently made on the basis of climate model simulations.

Climate scenarios are prepared with the aid of climate models and assumptions on future greenhouse-gas emissions.

A measure of how the mean global surface temperature would change if the atmospheric CO₂ concentration were doubled.

Earth’s natural climate system consists of several subsystems (spheres). The individual subsystems are closely connected by material and energy flows (e.g. the water cycle and carbon cycle) and respond to changes at varying speeds.

Climate variability refers to fluctuations in the mean status and other statistical parameters concerning the climate at all spatial and temporal scales above individual weather events.

A type of climate feedback in which the characteristics of clouds change in response to other atmospheric changes.

Chemical formula for the compound carbon dioxide.

Convergent motion of ice floes, which increases the ice concentration.

Computer tomography (CT) can be used to create three-dimensional representations of an object’s internal and external structure, allowing details to be recognised on a micrometre scale.

In the context of international law, the Conference of the Parties (COP) is the highest body at an international convention, e.g. the UNFCCC in 1992.

Conference of the Parties (COP).

In an IPCC Report, the standard term used to describe the level of confidence in a given statement. The IPCC defines this term in the introduction.

The theory of continental drift describes the gradual motion, division and fusion of continents.

The term “continental shelf” refers to a region that lies underwater (shelf sea) and extends from the coastline to a depth of ca. 200 metres.

Part of the ocean separating a continental shelf from the deep-sea floor. Continental slopes are characterised by a sudden increase in water depth and extend from the outer edge of a given continental shelf to a depth of between 3,000 and 4,000 metres. These slopes are home to various geological phenomena, such as underwater gorges, canyons, trenches and other structures. They also offer an important habitat for deep-sea organisms, as they are rich in nutrients and sediments from the continental shelf.

In the ocean and atmosphere, the vertical and turbulent motion of water / air, usually due to density changes, is referred to as convection.

The fading of colour that occurs when a coral loses the symbiosis with its energy-providing organisms.

Corals are small animals known as polyps, roughly resembling miniature sea cucumbers, that are capable of forming colonies. These polyps form a shared skeleton which, in some species, provides the foundation for a coral reef.

Fictitious force in rotating systems that deflects a particle’s motion perpendicular to its initial direction of motion. Does not affect motion in the direction of the rotational axis.

Any fracture in the ice that has not yet led to separation or calving. This includes all fractures that have not yet led to ice breakup.

The community of plankton organisms that live within the sea ice, primarily phytoplankton, but to a lesser extent also zooplankton.

The part of the climate system that encompasses snow, ice and frozen soil (including permafrost) above and below the surface of the Earth and ocean surface.

The decibel (dB) is the unit of measurement for loudness.

Microorganisms that break down other lifeforms’ organic excretions and the organic substances left behind when they die, converting them into simple inorganic compounds.

Water masses at depths below ca. 1,000 m, which are formed by convection and overflow and spread from the convection areas to the interior ocean.

General term for compressed ice.

A density anomaly is a phenomenon in which a given substance’s density does not change with temperature or pressure in a linear manner. Instead, the density peaks at a certain temperature and/or pressure before declining again.

Detritus refers to particulate material produced by the decomposition of dead plants and animals. In the context of water, it also includes suspended organic sediments.

Describes a potential future climate and associated drivers. Development paths are also referred to as climate scenarios.

Microalgae.

Transformation of one form of energy into another.

Dissolved inorganic carbon (DIC) refers to the total amount of dissolved inorganic carbon in water. It can be found in various carbonate species (bicarbonates, carbon dioxide and carbonates). The ratios of the various forms influence the pH value of the water and can reduce surface water’s ability to absorb CO₂.

DOC (dissolved organic carbon) generally refers to organic carbon compounds. A sum parameter, it is used to measure the total amount of dissolved, organic compounds. DOC particles are smaller than 0.45 µm in diameter.

Refers to changes in a given parameter in the course of the day.

This term is used to describe a type of sea-ice motion in which the ice generally drifts apart.

Due to divergent motion, the ice concentration is reduced, causing any tension in the ice to subside.

Mathematical technique used to apply the projections in global climate models to the regional scale.

The distance between the underside of sea ice and the ocean’s surface.

A term used to broadly describe an area covered by sea ice, regardless of the type or distribution – except for fast ice and new ice. Examples include ice floes formed when grease ice or slush freezes in a choppy sea, or when sheets of new ice break up.

Ice on rivers, lakes or seas that moves in response to wind, currents or other forces.

Drought refers to a lack of water, most often caused by insufficient precipitation and / or increased evaporation due to higher temperatures (or wind).

Dynamic regional models “reconstruct” Earth’s climate system on the basis of physically describable relations.

Solid, outermost layer of the Earth, with an average depth of 35 – 40 km.

Surface current in the Southern Ocean.

A system of mutually influencing living organisms and their physical environs. The definition of an ecosystem’s borders varies, depending on the respective research focus. Accordingly, the scale of ecosystems can range from very small to global.

Ocean currents created by the Earth’s rotation and winds.

A naturally occurring climate phenomenon formed in the Pacific between the west coast of South America and east coast of Asia (Australia, Indonesia).

Electromagnetic induction surveying.

The EM-Bird is a sensor used to determine the thickness of sea ice by helicopter or aeroplane

Earth System Model of Intermediate Complexity.

Release of substances, gases, etc. from natural or anthropogenic sources into the environment.

Emissions scenarios are potential future development paths for human emissions of greenhouse gases and aerosols.

Projections on future emissions paths or observed emissions patterns.

A given surface’s ability to emit energy, measured against a perfectly black body with 100% emissivity.

Refers to species that are only found in naturally demarcated geographic regions.

Energy is the ability to do work, produce heat or emit light. It describes the status of a body and is a conserved quantity. In a closed system, the total energy remains unchanged.

The difference between total incoming energy and total outgoing energy.

The relation between energy input and energy utilisation in a system, conversion process or activity.

Acronym for “El Niño – Southern Oscillation”, is a general term for the system of Pacific teleconnections produced by feedbacks between these two phenomena.

Describes the extent to which a given policy, measure or instrument achieves a specific, decisive or desired environmental effect.

Organisms that live on plants but are not parasitic are epiphytic. Examples include algae, lichens and mosses.

A unit of measurement used to compare the emissions of different greenhouse gases on the basis of their GWP (global warming potential).

The process of natural removal and transport of soil and rock in response to weathering and loss of mass due to the influence of waterways, glaciers, waves, wind and groundwater.

Measuring sea ice in motion on the basis of a static system.

Bioluminescent crustaceans (krill) are marine crustaceans with naked gills. They are chiefly filter feeders and can emit light.

Krill.

A substance in phase equilibrium

The transition of a liquid into a gas without reaching the boiling point.

External forces are forces from outside the climate system that cause changes in the system.

When an entire species dies out worldwide.

EPSs are produced by various species of bacteria and cover the cell as a capsule. The capsule performs a wide range of functions, not all of which are fully understood.

An extreme weather event is one that rarely occurs at a given place and in a given season.

Frequently Asked Questions.

Sea ice that is normally anchored to the place where it first formed.

The edge between the fast ice and drifting ice or drift-ice edge at a given time.

A type of sea-ice overlapping in which parts of two ice floes are forced over and under one another in an alternating, “fingerlike” pattern.

Sea ice that has grown for one winter at most, having developed from young ice.

Flagellates are single-celled organisms with whip-like appendages used for locomotion. Flagellates can be phototrophic or heterotrophic.

A narrow marginal zone between drifting ice and fast ice in which the pieces of ice are scattered about chaotically. Formed along the fast-ice edge by shearing motion and the influences of powerful winds and currents on drifting ice.

A navigable lead (waterway) between drifting ice and fast ice.

Sea ice that is flooded with water and wet snow.

Carbon-based fuels derived from fossil carbon dioxide deposits, including coal, peat, oil and natural gas.

Emissions of greenhouse gases (esp. carbon dioxide) produced by burning fuels from fossil carbon deposits, including coal, oil and natural gas.

Material quality resulting from mechanical overloading. Every hole and crack in very tight, compact or compressed pack ice, fast ice, or individual floes.

An area with multiple fractures in the ice.

Compression processes in which the ice is constantly deformed, leading to cracks.

Free-floating ice needles or wafers.

Refers to the portion of sea ice extending above the ocean’s surface.

A standard for the intensity of below-zero temperatures in a given timeframe, frequently used in the USA.

Fog-like clouds produced when cold air comes into contact with comparatively warm water. Frost smoke can occur over gaps (leads) in the ice or in the lee of the ice edge and can persist during the formation of new ice.

The most commonly used distribution in statistics.

Geoengineering refers to intentional and focused – and most often implemented on a large scale – interventions in the climate system, which are intended to mitigate climate warming due to human activities (anthropogenic climate warming).

Greenhouse gas.

A lake formed by the meltwater from a glacier.

Glaciers are huge masses of ice that gradually flow from mountains down into valleys.

Refers to the science of ice, which was initially limited to the study of glaciers.

The average surface temperature (land / water) in a certain timeframe.

The GWP quantifies the effects of all greenhouse gases on the basis of the effects of CO₂, the most relevant greenhouse gas for human beings, which is accordingly assigned a GWP of 1.

A supercontinent that encompassed today’s South America, Africa, the Indian Subcontinent, Australia and the Antarctic.

Ice needles / ice wafers that clump together, forming a thin, soup-like layer on the water’s surface.

Refers to the effect of greenhouse gases in the atmosphere on temperatures at a planet’s surface, e.g. the surface of the Earth, where temperatures rise.

Greenhouse gases are gaseous components of the atmosphere – both naturally occurring and anthropogenic – that absorb the radiation emitted by the Earth’s surface, the atmosphere itself, and clouds and reflect or radiate it back at specific wavelengths of the thermal infrared radiation spectrum.

Young ice, 10 – 15 cm thick.

Young ice, 15 – 30 cm thick.

Gigatonne (1 billion metric tons).

Partly halogenated chlorofluorocarbons.

Partly halogenated hydrofluorocarbons.

Transitional zone between water layers with different salinities

Collective term for the group of partly halogenated organic substances.

How organisms that require organic substances as a source of energy and carbon feed themselves.

Hydrofluorocarbons.

The Holocene is the current interglacial period, which began ca. 11,600 years ago.

Ice thrown together and stacked at random. After weathering, the sides of these hummocks are smooth.

Hydrography is a discipline that deals with the measurement and description of bodies of water.

The part of the climate system that encompasses liquid surface and subterranean water, e.g. oceans, seas, rivers, freshwater lakes, groundwater, etc.

An ice age or glacial period is characterised by a long-term temperature reduction in the Earth’s climate, which leads continental ice sheets and alpine glaciers to grow (glaciation).

One of the various types of algae communities found in first-year and multiyear sea ice.

The ratio (expressed in tenths) of the ice-covered surface to the overall water surface at a given time and in a discrete area.

A cylindrical core of ice retrieved from a glacier or ice sheet.

Refers to the motion of sea ice in one main direction.

The border between the open ocean and sea ice of any kind, whether fast or drifting, at a given time.

An area filled with drifting ice, consisting of floes of all sizes, and with a diameter of more than 10 km.

Any comparatively flat piece of sea ice that is at least 20 m wide.

The part of a pressure ridge that extends below the water’s surface.

A climatological term that refers to the projected maximum or minimum sea-ice extent in a given month or other timeframe, determined on the basis of years of observation.

Microsections.

A brittle, shiny crust of ice.

Extensive ice cover on land in the polar regions.

An ice shelf is a large, floating sheet of ice with an extensive level or slightly undulating surface, and which is connected to and fed by glaciers, ice flows or ice caps.

Thickness of sea ice.

A climate feedback concerning changes in the Earth’s albedo.

Absence of sea ice.

Icebergs are formed when large pieces of ice shelves or glaciers break away or calve and land in the water.

In-situ (“in-situation”) means “on site” and refers to readings or observations that are gathered directly on site, without the need for transporting samples or data elsewhere.

Discrepancies between two conditions, where both are considered valid but contradict one another.

A period of rapid industrial growth, with far-reaching social and economic consequences, that began roughly in the year 1750.

Huge ice masses that can be over 4,000 m thick, cover broad expanses of land, and form at the edges of glacier termini or break off (“calve”) at the ocean’s edge with vertical walls, producing icebergs in the process; today, only to be found in Greenland and the Antarctic.

Carbon compounds that are not based on carbon-carbon or carbon-hydrogen bonds. Examples of inorganic carbon include carbon dioxide (CO₂), carbon monoxide (CO), carbonates and bicarbonates.

In climate history and geology alike, an interglacial period is a phase with higher mean temperatures, located between two periods with lower mean temperatures – ice ages.

A warm phase within an ice age is referred to as an interglacial period.

Intergovernmental Panel on Climate Change.

Isostatic refers to a situation in which the forces affecting a given region or object are so balanced that the system as a whole remains in equilibrium. For example, when sea ice grows and its thickness increases, it gradually rises above the water level so as to maintain isostatic equilibrium.

A locally forming, cold and therefore heavy near-surface fall wind that is independent of regional air-pressure conditions and frequently observed over glaciers.

Algae chloroplasts.

Krill is a collective term for small swarming crustaceans.

By signing the Kyoto Protocol (1997), the international community embedded for the first time an absolute and legally binding limit on greenhouse-gas emissions in an international agreement.

Breastfeeding time, the time after childbirth when milk is produced and shared.

Measurements are taken along the path (of the trajectory). The measuring point moves with the subject.

How human beings put land to use.

Refers to changes in how land is used or managed by human beings.

“Altimeter missions” are used to measure the elevation of the Earth’s surface, and therefore also the elevation of the sea-ice surface.

Generally speaking, every navigable break or channel in the sea ice that is too wide to jump across. A lead can contain open water (open lead) or be covered with ice (ice-covered lead).

Sea ice that has not been affected by deformation / has not been deformed.

Optical measuring method used to assess the atmosphere with the aid of laser-based range finding.

The Earth’s crust and the topmost part of its mantle. The lithosphere forms our planet’s outermost shell and consists of individual plates that are in motion.

Inorganic chemical compounds that algae ingest in large quantities and require in order to produce biomass.

In oceanography, a marginal sea is a secondary sea that, unlike mediterranean seas, is situated on the edge of the mainland and is separated from the open ocean by archipelagos or peninsulas. Examples include the Bering Sea, North Sea, and Sea of Japan.

In glaciology, the difference between a body of ice’s mass gain and mass loss is referred to as its mass balance.

Autonomous measuring system that uses acoustic methods to determine sea-ice and snow thickness.

Refers to a group of small animals – as a rule, between 0.3 and 1 mm in diameter – that chiefly live in marine sediments but can also be found in terrestrial habitats. In terms of size, they lie between the microfauna and macrofauna.

Every summer, the snow cover on Arctic sea ice melts completely, leaving behind ponds of meltwater.

This global “conveyor belt” redistributes massive amounts of heat, salt, nutrients and gases among all oceans.

Multicellular, heterotrophic organisms belonging to the animal kingdom. Unlike single-celled organisms like protozoans, metazoans are composed of multiple cells, which are subdivided into specialised tissues and organs capable of performing a range of functions.

Gaseous hydrocarbon.

A type of electromagnetic wave.

An extensive underwater mountain range that can in some cases include individual islands above sea level.

Model used to explain the occurrence of glacial and interglacial periods by means of quasi-periodic variations in Earth’s orbit, which result in changed exposure to solar radiation.

Single-celled or multicellular eukaryotic lifeform (microorganism) that can use a mix of organic / inorganic sources of carbon, i.e., can also use photosynthesis.

Mixotrophs are those organisms that can use a mix of organic / inorganic sources of carbon, i.e., can also use photosynthesis.

Regulates the consumption and production of chemicals containing chlorine or bromine, which can destroy stratospheric ozone.

Old ice that is at least two metres thick and has survived at least two summers.

Chemical formula for nitrous oxide.

General term for newly formed ice.

A thin, elastic crust of ice, up to 10 cm thick.

Nitrous oxide (N₂O) is a ⁠greenhouse gas ⁠that is roughly 300 times as harmful to the climate as carbon dioxide (CO₂).

The North Atlantic Oscillation (NAO) is a characteristic and powerful atmospheric circulation phenomenon in the Northern Hemisphere.

The Northern Hemispheric Annular Mode (NAM, also Arctic Oscillation (AO)) is a manifestation of sea-level pressure differences between the Arctic and the middle latitudes of the Northern Hemisphere.

Process in which the pH value of seawater declines due to increased absorption of atmospheric carbon dioxide. This process is a direct effect of rising carbon dioxide concentrations in the atmosphere, which are primarily caused by human activities like burning fossil fuels.

The science of the ocean.

Ozone-depleting substance.

Sea ice that has survived at least one summer melting.

Deposited snow; the ice crystals’ original form can no longer be recognised. 

The degree to which a given substance can be penetrated by light or electromagnetic waves.

A large, freely navigable water zone that is nearly ice-free. The ice concentration is less than 1/10.

Group of carbon compounds based on carbon-carbon or carbon-hydrogen bonds and which can be found in or are produced by living organisms.

Refers to a process connected to the diffusion of molecules or ions through a semipermeable membrane, i.e., the exchange of mixable liquids through a membrane.

The pressure between two fluids with different concentrations that are separated by a semipermeable membrane.

Overfitting is a problem that arises in statistical modelling, machine learning, and artificial intelligence when a given model is overly adjusted to specific examples in the training data and is consequently no longer capable of making general predictions regarding new, unfamiliar data. Overfitting occurs when a model’s complexity is too great in relation to the available training data, or when the model – due to repetitions of the training that are too long or too numerous – inadvertently learns the training data “by heart.”

A gaseous component of the atmosphere.

A layer spanning from ca. 12 to 40 km above the Earth’s surface.

Floes that are compressed (primarily by wind) into extensive masses of ice.

Stacked blocks of broken ice produced by intense piling.

The science of Earth’s climatic history.

An index that uses temperature and precipitation data to predict droughts.

Small, round ice floes that resemble pancakes.

Parametrisation is the process by means of which simplified descriptions (most often mathematical in nature) and a limited number of parameters or variables are used to portray complex systems or processes in a form suitable for creating mathematical models or simulations.

Particular organic carbon (POC) is a form of organic carbon found in bodies of water in particulate form, both as part of living cells, and as dead material. POC is an important food source for various marine organisms and, as a natural carbon sink, has an effect on the carbon cycle.

The pelagic or open water zone is a term used in marine biology and refers to that part of a water body that is open and not influenced by any structures on its floor. It is essentially the counterpart to the benthic zone, the bottommost zone of a body of water.

A term that essentially means “swimming in the open water”. It refers to organisms that live in the open waters of the ocean and large inland water bodies (and not close to the bottom or near the shore).

A parameter used in the statistical evaluation of e.g. measurements and which provides a distribution value.

Ground (soil or rock, together with ice and organic material) that continuously remains below 0°C (i.e., is frozen) for at least two consecutive years.

From the Latin pondus Hydrogenii (a measurement of an aqueous solution’s acidity or basicity).

A phase transition is a physical process by means of which a given material changes from one state to another, i.e., changes from a solid, liquid or gaseous state to another state.

An organism that can use sunlight as an energy source in order to convert inorganic material into organic material, i.e., to engage in photosynthesis.

Encompasses all techniques and devices used to record, process and store primarily geometric information (e.g. form, size, position) on objects and processes using photographic images. Object points are identified and measured in two or more images.

Process in which green plants use sunlight, carbon dioxide and water to produce biomass and emit oxygen.

The entirety of plant organisms drifting or floating in the water.

Organisms that virtually passively float in the water. Can be divided into phytoplankton and zooplankton.

A layer of delicate crystals below the sea ice, which can be up to several metres thick. It is formed from ice-shelf meltwater in the Antarctic through crystallisation in the open water column.

Any non-rectilinear patch of open water in sea ice.

First and foremost, these buoys transmit their own position.

Parts per billion.

Parts per million.

Atmospheric components that are not themselves greenhouse gases or aerosols, but which affect greenhouse-gas or aerosol concentrations.

Projected outcome, based on e.g. established physical, technological, economic, social and behavioural patterns.

The age before the Industrial Revolution of the late 18^th and early 19^th century, after which the consumption of fossil fuels for mechanisation began to rise.

General term for any extended (when viewed from above) wall-like collection of ice blocks, produced by ice deformation.

A term borrowed from ecology, refers to consumers in the first link of the food chain, which feed on living or recently dead autotrophic organisms (autotrophs, producers).

Organisms that use photosynthesis or chemosynthesis to produce organic substances from inorganic substances.

The amount of biomass produced by autotrophic organisms (primary producers) from inorganic substances in a given ecosystem and in the course of a year.

Scientific findings are often subject to various uncertainties, due e.g. to unanswered questions or to processes that have yet to be sufficiently explained. Consequently, IPCC Reports also include information on the uncertainty of findings and the respective probability of future events.

A possible future development of one or more parameters, often calculated with the aid of a model.

Organisms that lack a nucleus.

Protists are eukaryotic organisms, chiefly single-celled but occasionally multicellular.

Protozoans are single-celled lifeforms and some of the simplest organisms on our planet. They live independently or as parasites.

A climate indicator or substitute for a climatic development.

Stands for Radio Detection and Ranging and is an active sending and receiving system in the microwave domain.

Difference between radiative flows received by the Earth-atmosphere system in the form of shortwave radiation from the sun and those reflected back into space by the same system in the form of longwave radiation.

The radiation balance is the difference between the total incoming energy and energy reflected back into space at the edge of the atmosphere. In addition, the radiation balance takes into account the changes in energy fluxes caused by absorption, emission, scattering and reflection.

Change in the net energy balance (incoming energy minus outbound energy; expressed in watts per square metre: Wm^-2) at the tropopause (border between the troposphere and stratosphere) due to changes in an external forcing factor affecting the climate system.

Process in which one piece of ice is shoved atop another; most apparent in the case of new ice and young ice (see also Finger rafting), but actually typical for ice of any thickness.

Reanalyses are created by combining extensive Earth observations with an atmospheric or ocean model through what is known as data assimilation.

The use of climate indicators to determine the (generally, past) climate.

Value for a quantifiable parameter that is used to assess an alternative outcome, e.g. using a scenario without intervention as a reference for analysing intervention scenarios.

Reflectivity (p) determines the percentage of the light that is reflected back when a light beam strikes a surface.

Refers to the process in which organic material like dead plants and animals is broken down by bacteria and other microbial organisms, producing inorganic nutrients like nitrate, phosphate and carbon. These nutrients can in turn be absorbed by plants and other organisms, promoting growth and fuelling metabolism. Remineralisation plays an important part in global carbon and nutrient cycles and helps preserve the health of ecosystems.

Taken from ongoing or repeating natural energy flows, includes CO₂-free technologies like solar energy, hydropower, wind, tides, waves and geothermal, as well as CO₂-neutral technologies like biomass.

Radiative forcing.

Study of the flow of matter.

Refers to the process in which pressure ridges are formed.

Salinity of water or soil. Represents the amount of dissolved salt in water.

The IPCC’s Second Assessment Report.

Sastrugi are rippling grooves or ridges in the snow.

The Scientific Committee for Antarctic Research is a non-governmental organisation and was founded in 1958.

Scenarios are based on a range of assumptions concerning global developments like population growth, economic and social trends, technological advances, resource consumption and environmental management.

The totality of ice found on and in the ocean.

The sea surface temperature is the mean temperature in the near-surface metres of the ocean.

The sea-ice avifauna are the birds of the sea ice.

The sea-ice cover has been determined on the basis of satellite data for over 30 years. As a rule, presented as the “sea-ice extent”, as the “sea-ice area” in square kilometres, or as the “sea-ice concentration”.

The height of the ocean’s surface. It approximates an equipotential surface of the Earth’s gravitational field. When it changes, it is referred to as sea-level change.

Organisms in a given ecosystem that, at the 3^rd level of the food pyramid, heterotrophically live off of primary consumers, e.g. fish that feed on zooplankton.

In ecology, the production of biomass or energy at the level of consumers and decomposers.

A sample that is collected by vertical drilling into sea sediment or sediment from inland water bodies.

CO₂ sequestration refers to the storage of carbon dioxide (CO₂) deep underground.

Shallow waters on the edge of a continent and extending from a coast to a shelf edge, which can lie up to 200 metres below the surface. Shelf seas are typically several tens of kilometres to a few hundred kilometres wide and offer vital habitat for marine organisms. They are also important resources for the fishing industry and oil and gas exploration.

A lead between drifting ice and the shore or between drifting ice and an ice front. 

A collection of spongy white ice clumps measuring a few centimetres wide.

A single-ping reading refers to the practice of gathering data with scientific instruments and using just one signal or “ping”. Single-ping readings are typically used in order to capture short-term impulses, whereas continuous readings are taken over extended timeframes. In hydrology and oceanography, Acoustic Doppler Current Profilers (ADCPs) are often used to take single-ping readings of the flow speed, direction and turbulence in a river or ocean.

Any process, mechanism or activity that absorbs a greenhouse gas, aerosol, or a precursor of a greenhouse gas or aerosol, thus removing it from the atmosphere.

Snow that is saturated with water and lies on the land or ice; or a soupy clump of floating ice formed in the cooled water after heavy snowfall.

Since 2012, snow buoys have been used to measure snow thickness, atmospheric temperature and pressure over the sea ice.

Scientific investigation and description of layer formation in snow cover. In this regard, properties like snow depth, snow crystal forms, grain size, and density are assessed and recorded in order to draw conclusions regarding the temporal progression and spatial distribution of changes in the snow cover. Snow stratigraphy is especially important for climate research and for gauging the risk of avalanches.

Ice with a uniform grain size, which is created when grease ice / slush freezes completely.

Changes in the sun’s properties, which are connected to turbulence in its extremely hot gas and constant changes in its magnetic field, are referred to as solar activity. The changes can be cyclical or irregular.

The solar cycle or sunspot cycle refers to periodicity in the frequency of sunspots. It describes a period of eleven years on average, which is also referred to as the Schwabe cycle in honour of Samuel Heinrich Schwabe.

Electromagnetic radiation emitted by the sun.

Soot particles are chiefly formed during the incomplete combustion of fossil fuels and biomass.

Any process, mechanism or activity that releases a greenhouse gas, aerosol, or a precursor of a greenhouse gas or aerosol into the atmosphere.

The Southern Oscillation is a periodic variation (every three to five years) in air surface pressure between the tropical western Pacific and southeast Pacific, which produces effects on wind systems and ocean surface currents.

The climate can vary over a broad spectrum of spatial and temporal scales. Spatial scales range from local (less than 100,000 km²) to regional (100,000 to 10 million km²) to continental (10 to 100 million km²). Temporal scales can range from seasonal to geological (hundreds of millions of years).

(IPCC) Summary for Policymakers.

(IPCC) Special Report on Carbon Capture and Storage. (Special Report on Carbon Capture and Storage)

(IPCC) Special Report on Emission Scenarios. (Special Report on Emission Scenarios) 

An emissions scenario for the IPCC’s Third and Fourth Assessment Reports (2001 and 2007).

(IPCC) Special Report on Ocean and Cryosphere in a Changing Climate (2019). (Special Report on Ocean and Cryosphere in a Changing Climate)

Maintaining a constant atmospheric concentration of one or more greenhouse gases.

Main tracks of extratropical disruptions, which manifest as sequences of high- and low-pressure cells.

Refers to algal chains that grow downward from the ice in long strands.

Highly stratified atmospheric layer located above the troposphere at between ca. 10 and 50 km above the Earth’s surface.

A device or system installed in a coastal location (and in some cases, in the deep sea) that constantly measures the water level surface elevation in relation to the surrounding land. The mean value over time for these surface elevation readings is the observed relative sea-level change.

The direct transition of a solid into a gas.

Ring-shaped system of wind-driven ocean currents. Rotates clockwise in the Northern Hemisphere and counter-clockwise in the Southern Hemisphere.

One of the six greenhouse gases that the Kyoto Protocol calls for combating.

Stems from the concept of a sustainable society and the management of renewable resources. Combines political, societal, economic and environmental aspects.

“Sympagic” is an adjective used to describe an ecosystem found in regions with ice and snow. It refers to the communities of organisms whose lives are closely connected to sea ice or glacier ice.

Huge icebergs (in some cases with an area of several square kilometres) with a level, smooth surface, and which can extend up to 100 m above the water’s surface. Produced by calving from ice shelves.

The IPCC’s Third Assessment Report.

In connection with sea level, this refers to an increase in volume (and decrease in density) due to the warming of water.

Thermal hysteresis refers to the difference (hysteresis) between the melting point and freezing point of a given solution.

Thermal radiation emitted by land surfaces or objects in the longwave infrared range.

Electronic component used to measure temperature changes, which it responds to by changing its electrical resistance. The name “thermistor” is derived from the words “thermal” and “resistor”. As a rule, thermistors are made of semi-conductive materials like silicon, germanium or metal oxides, and are frequently used in a broad range of applications, e.g. in air-conditioning systems, household appliances, medical equipment, and in aerospace contexts.

A buoy equipped with a thermistor chain that measures temperature distribution from the atmosphere, through the snow and sea ice, to the ocean.

Transitional water layer characterised by rapid temperature changes.

Thermohaline circulation, colloquially referred to as the ocean conveyor belt, is an oceanographic circulation pattern at the surface of the ocean and in its depths. Connecting four of the five oceans, it forms a global cycle.

Organisms in a given ecosystem that, at the 3^rd level of the food pyramid, heterotrophically live off of secondary consumers, e.g. predatory fish.

Models that use macroeconomic theory, econometric and optimisation techniques in order to aggregate economic variables.

TOC (total organic carbon) refers to the total amount of carbon from organic compounds in a given sample.

Total primary energy supply.

All gases found in the atmosphere in lower concentrations than the three main components nitrogen (78%), oxygen (21%) and argon (ca. 1%) are referred to as trace gases.

Specific substances or materials used to track the transport or conversion of elements or compounds in a given ecosystem or biogeochemical cycle.

Tree rings or growth rings reflect different developmental phases in a vegetation period.

In IPCC Reports, a trend refers to a constant change in the value of a given variable over time.

A trophic level refers to the level or position in the food chain or food web of a given ecosystem, which is determined by the number of energy-transmitting steps that are required to reach that level (energy pyramid).

A tropical cyclone is a low-pressure system characterised by structured convection, severe storms, and a closed low-level atmospheric circulation at its centre.

The lowermost part of the atmosphere, from the Earth’s surface to ca. 10 km in the middle latitudes (ranging from 9 km in the high latitudes to 16 km in the tropics on average), where clouds and meteorological phenomena arise.

(IPCC) Technical Summary.

Refers to a vegetation zone found in Arctic and subarctic regions and characterised by extremely low temperatures and brief vegetation periods.

Old sea ice that has only survived one summer melting.

Uncertainty is a means of expressing the extent to which a given value is uncertain (e.g. the future status of the climate system).

United Nations Framework Convention on Climate Change.

Goal is “to achieve stabilization of atmospheric concentrations of greenhouse gases at levels that would prevent dangerous anthropogenic interference with the climate system”.

Region in which currents of cold and dense seawater rise to the surface along continental coasts, driving warm water away from the coast in the process.

The relative heat of cities compared to surrounding rural areas.

The Walker circulation (or Walker cell) is an atmospheric system over the equatorial Pacific.The air sinks over the East Pacific (off the coast of South America) and rises over the West Pacific (off the coast of Indonesia).

In the context of glaciology, erosion and sedimentation processes that gradually remove the irregularities in the surface of ice.

In physics notation, unit for energy intensity, watts per square metre.

Ice in a transitional state between nilas and first-year ice, and which is 10 – 30 cm thick.

The totality of all organisms that drift in the water and do not use photosynthesis: in the ocean, predominantly crustaceans.

Degrees Celsius.

The 10 °C isotherm is an imaginary line connecting all points with a mean temperature of less than 10 °C in high summer.