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Glossary

The English version of our glossary is currently under construction and will be regularly updated.

A

Ablation

Melting and evaporation on glaciers and in snow fields.

Acclimatisation

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

ACIA

Arctic Climate Impact Assessment.

Adaption

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

Adsorption

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

Advection

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

Aerosols

Solid or liquid particles in the air.

Albedo

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

Allochthonous

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

AMAP

Arctic Monitoring and Assessment Programme.

Anchor ice

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

Anions

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-).

Anisotropy

Directional dependence of a substance’s property

Annular Mode

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

Antarctic Circumpolar Current

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

Antarctic Convergence

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.

Antarctic Divergence

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

Antarctic Oscillation (AAO)

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.

Antarctic Treaty System

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

Anthropogenic

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

Anthropogenic emissions

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

Archaeans

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.

Arctic

polar region located at the northernmost part of Earth

Arctic Oscillation (AO)

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

Assimilation

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

Atmosphere

The gaseous envelope surrounding the Earth.

Atmospheric deposition

Refers to the deposition of atmospheric substances.

Aurora australis / Aurora borealis

The Southern and Northern Lights.

Autochthonous

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

Autotrophy

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

Azimuth

Horizontal direction in a three-dimensional coordinate system

B

Beaufort Gyre

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.

Benthos

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

Biocoenosis

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

Biodiversity

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

Bioluminescence

Bioluminescence refers to lifeforms that naturally produce light.

Biomass

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

Biome

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

Biosphere

The entirety of the Earth that is home to lifeforms.

Biota

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

BMWK

Federal Ministry for Economic Affairs and Climate Action.

Bottom-up models

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

Brash ice

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

Breakup

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

Brine

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

Brine channels

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

Bummock

The part of a hummock that extends underwater.

Buoys

Autonomous measuring systems.

C

C

Chemical symbol for carbon.

Calving

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

Candle ice

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.

Carbon capture and storage dioxide (CCS)

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.

Carbon cycle

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

Carbon dioxide (CO₂)

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

Carbon dioxide intensity

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

Cations

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+).

CCS

Carbon capture and storage.

CDM

Clean Development Mechanism.

CFCs

The abbreviation for chlorofluorocarbons.

CH₄

Chemical formula for the compound methane.

Chloroplasts

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.

Circumpolar Current

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

Climate

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

Climate archive

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

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.

Climate factors

Refers to factors that affect various components of the climate.

Climate feedback

Interaction mechanism between processes in the climate system.

Climate inertia

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.

Climate model

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.

Climate prediction

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.

Climate projection

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 scenario

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

Climate sensitivity

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

Climate system

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

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.

Cloud feedback

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

CO₂

Chemical formula for the compound carbon dioxide.

Compacting

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

Computer tomography (CT)

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.

Conference of the Parties

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)

Conference of the Parties (COP).

Confidence

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.

Continental drift

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

Continental shelf

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.

Continental slope

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.

Convection

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

Coral bleaching

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

Corals

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.

Coriolis force

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.

Crack

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.

Cryoplankton

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

Cryosphere

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.

D

dB

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

Decomposers

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

Deep water

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.

Deformed ice

General term for compressed ice.

Density anomaly

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

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.

Development path

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

Diatoms

Microalgae.

Dissipation

Transformation of one form of energy into another.

Dissolved inorganic carbon (DIC)

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.

Dissolved organic carbon (DOC)

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.

Diurnal variation

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

Divergence

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

Diverging / loosening up of drifting ice or ice fields

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

Downscaling

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

Draft

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

Drifting ice

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.

Drifting ice

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

Drought

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

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

E

Earth’s crust

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

East Wind Drift

Surface current in the Southern Ocean.

Ecosystem

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.

Ekman spiral

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

El Niño

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

EM induction surveying

Electromagnetic induction surveying.

EM-Bird

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

EMIC

Earth System Model of Intermediate Complexity.

Emissions

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

Emissions scenario

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

Emissions trajectories

Projections on future emissions paths or observed emissions patterns.

Emissivity

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

Endemic

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

Energy

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.

Energy balance

The difference between total incoming energy and total outgoing energy.

Energy efficiency

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

ENSO

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

Environmental effectiveness

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

Epiphytic

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

Equivalent carbon dioxide (CO₂e) concentration

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

Erosion

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.

Eulerian approach

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

Euphausiacea

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

Euphausiacea superba

Krill.

Eutectic system

A substance in phase equilibrium

Evaporation

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

External forces

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

Extinction

When an entire species dies out worldwide.

Extracellular polymeric substances (EPSs)

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.

Extreme weather event

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

F

FAQ

Frequently Asked Questions.

Fast ice

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

Fast-ice edge

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

Finger rafting

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.

First-year ice

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

Flagellates

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

Flaw

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.

Flaw lead

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

Flooded ice

Sea ice that is flooded with water and wet snow.

Fossil fuels

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

fossil-fuel emissions

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

Fracture

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

Fracture zone

An area with multiple fractures in the ice.

Fracturing / crack formation in the ice

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

Frazil ice

Free-floating ice needles or wafers.

Freeboard

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

Freezing degree days (FDDs)

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

Frost smoke

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.

G

Gaussian (normal) distribution

The most commonly used distribution in statistics.

Geoengineering

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).

GHG

Greenhouse gas.

Glacial lake

A lake formed by the meltwater from a glacier.

Glacier

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

Glaciology

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

Global mean surface temperature

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

Global warming potential (GWP)

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.

Gondwana

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

Grease ice

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

Greenhouse effect

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 gas

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.

Grey ice

Young ice, 10 – 15 cm thick.

Grey-white ice

Young ice, 15 – 30 cm thick.

Gt

Gigatonne (1 billion metric tons).

H

H-CFCs

Partly halogenated chlorofluorocarbons.

H-HFCs

Partly halogenated hydrofluorocarbons.

Halocline

Transitional zone between water layers with different salinities

Halogenated hydrocarbons

Collective term for the group of partly halogenated organic substances.

Heterotrophy

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

HFCs

Hydrofluorocarbons.

Holocene

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

Hummocked ice

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

Hydrography

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

Hydrosphere

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

I

Ice age

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).

Ice algae

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

Ice concentration

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

Ice core

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

Ice drift

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

Ice edge

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

Ice field

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

Ice floe

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

Ice keel

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

Ice limit

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.

Ice micrographs

Microsections.

Ice rind

A brittle, shiny crust of ice.

Ice sheet

Extensive ice cover on land in the polar regions.

Ice shelf

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.

Ice thickness

Thickness of sea ice.

Ice-albedo feedback

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

Ice-free

Absence of sea ice.

Iceberg

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

In-situ

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.

Inconsistencies

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

Industrial Revolution

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

Inland ice

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.

Inorganic carbon

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.

Interglacial period

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.

Interglacial period

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

IPCC

Intergovernmental Panel on Climate Change.

isostatic

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.

K

Katabatic wind

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

Kleptoplasts

Algae chloroplasts.

Krill

Krill is a collective term for small swarming crustaceans.

Kyoto Protocol

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.

L

Lactation period

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

Lagrangian approach

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

Land use

How human beings put land to use.

Land-use change

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

Laser altimetry

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

Lead

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).

Level ice

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

LIDAR

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

Lithosphere

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.

M

Macronutrients

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

Marginal sea

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.

Mass balance (of glaciers, ice caps or ice sheets)

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

Mass-balance buoy

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

Meiofauna

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.

Melt pond

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

Meridional Overturning Circulation (MOC)

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

Metazoans

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.

Methan (CH₄)

Gaseous hydrocarbon.

Microwaves

A type of electromagnetic wave.

Mid-ocean ridge

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

Milanković cycles

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.

Mixotrophic protist

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

Mixotrophy

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

Montreal Protocol

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

Multiyear ice

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

N

N₂O

Chemical formula for nitrous oxide.

New ice

General term for newly formed ice.

Nilas

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

Nitrous oxide (N₂O)

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

North Atlantic Oscillation (NAO)

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

Northern Annular Mode (NAM)

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.

O

Ocean acidification

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.

Oceanography

The science of the ocean.

ODS

Ozone-depleting substance.

Old ice

Sea ice that has survived at least one summer melting.

Old snow

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

Opacity

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

Open water

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

Organic carbon

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

Osmotic

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.

Osmotic pressure

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

Overfitting

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.”

Ozone

A gaseous component of the atmosphere.

Ozone layer

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

P

Pack ice

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

Pack-ice hummocks

Stacked blocks of broken ice produced by intense piling.

Paleoclimatology

The science of Earth’s climatic history.

Palmer Drought Severity Index (PDSI)

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

Pancake ice

Small, round ice floes that resemble pancakes.

Parametrisation

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.

Particulate organic carbon (POC)

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.

Pelagic

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.

Pelagic

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).

Percentile

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

Permafrost

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.

pH value

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

Phase transition

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.

Photoautotrophic organism

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.

Photogrammetry

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.

Photosynthesis

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

Phytoplankton

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

Plankton

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

Platelet ice

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.

Polynya

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

Positioning buoys

First and foremost, these buoys transmit their own position.

ppb

Parts per billion.

ppm

Parts per million.

Precursors

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

Prediction

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

Preindustrial

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

Pressure ridges

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

Primary consumers

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).

Primary producers

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

Primary production

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

Probability

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.

Projection

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

Prokaryotes

Organisms that lack a nucleus.

Protists

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

Protozoans

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

Proxy

A climate indicator or substitute for a climatic development.

R

RADAR

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

Radiation balance

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.

Radiation balance

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.

Radiative forcing

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.

Rafting

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

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

Reconstruction

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

Reference value or scenario

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

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

Remineralisation

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.

Renewable energy

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.

RF

Radiative forcing.

Rheology

Study of the flow of matter.

Ridging / formation of pressure ridges

Refers to the process in which pressure ridges are formed.

S

Salinity

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

SAR

The IPCC’s Second Assessment Report.

Sastrugi

Sastrugi are rippling grooves or ridges in the snow.

SCAR

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

Scenario

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.

Sea ice

The totality of ice found on and in the ocean.

Sea surface temperature

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

Sea-ice avifauna

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

Sea-ice cover

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”.

Sea-level change

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.

Secondary consumers

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

Secondary production

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

Sediment core

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

Sequestration

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

Shelf sea

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.

Shore lead

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

Shuga

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

Single-ping reading

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.

Sink

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.

Slush

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.

Snow buoy

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

Snow stratigraphy

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.

Snow-ice

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

Solar activity

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.

Solar cycle (“11-year cycle”)

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.

Solar radiation

Electromagnetic radiation emitted by the sun.

Soot

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

Source

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

Southern Oscillation

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.

Spatial and temporal scales

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).

SPM

(IPCC) Summary for Policymakers.

SRCCS

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

SRES

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

SRES scenario

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

SROC

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

Stabilisation

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

Storm tracks

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

Strand community

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

Stratosphere

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

Stream gauge

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.

Sublimation

The direct transition of a solid into a gas.

Subtropical gyre

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

Sulphur hexafluoride (SF6)

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

Sustainable development

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

Sympagic

“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.

T

Tabular icebergs

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.

TAR

The IPCC’s Third Assessment Report.

Thermal expansion

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

Thermal hysteresis

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

Thermal infrared radiation

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

Thermistor

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.

Thermistor chain buoy

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

Thermocline

Transitional water layer characterised by rapid temperature changes.

Thermohaline circulation

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.

Third level consumers

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

Top-down models

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

Total organic carbon (TOC)

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

TPES

Total primary energy supply.

Trace gas

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.

Tracers

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

Tree rings

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

Trend

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

Trophic levels

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).

Tropical cyclones

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

Troposphere

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.

TS

(IPCC) Technical Summary.

Tundra

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

Two-year ice

Old sea ice that has only survived one summer melting.

U

Uncertainty

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

UNFCCC

United Nations Framework Convention on Climate Change.

United Nations Framework Convention on Climate Change (UNFCCC)

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

Upwelling region

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.

Urban heat islands

The relative heat of cities compared to surrounding rural areas.

W

Walker circulation

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).

Weathering

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

Wm⁻²

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

Y

Young ice

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

Z

Zooplankton

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

0

°C

Degrees Celsius.

10 °C isotherm

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