Glossary

The lower altitude area of a glacier or ice sheet where ice mass loss is higher than accumulation due to melting, evaporation, calving, and other processes

The higher altitude area of an ice sheet or glacier where it gains mass via precipitation (falling snow)

Antarctic Ice Sheet: the thick sheet of ice that covers the continent of Antarctica

The period of time during which human activities have had an environmental impact on the Earth regarded as constituting a distinct geological age

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The solid rock beneath soil and other surface materials

The process in which carbon atoms continually travel from the atmosphere to Earth and then back into the atmosphere. Human activities have a tremendous impact on this cycle. Burning fossil fuels, changing land use, and using limestone to make concrete all transfer massive quantities of carbon into the atmosphere. As a result, the amount of carbon dioxide in the atmosphere is rapidly rising — and it is now greater than at any time in the last 3.6 million years.

A colourless, odourless gas that is an important part of Earth’s atmosphere. One molecule of carbon dioxide is made of one atom of carbon and two atoms of oxygen, and its symbol is CO2. Plants use carbon dioxide during photosynthesis, and animals (including humans) breathe it out during respiration. Carbon dioxide is also a heat-trapping greenhouse gas, and the amount of carbon dioxide in Earth’s atmosphere has increased significantly since the Industrial Revolution due to humans’ burning of fossil fuels.

A long-term shift in average, typical temperature and weather patterns. (Weather is the temperature, humidity, wind, rainfall, and other atmospheric conditions over short periods—from hours to weeks.)

A highly complex global system with five parts, the atmosphere (air), hydrosphere (water), cryosphere (ice and permafrost), lithosphere (Earth’s rocky upper layer), and biosphere (living things), and the interactions between them.

A result of Earth’s rotation on ocean currents and weather patterns; makes storms and swirl clockwise in the Southern Hemisphere and counterclockwise in the Northern Hemisphere

A type of lithified (turned into rock) sedimentary rock that consists of poorly sorted sediment particle ranging in size from clay to boulders

Diatoms are a type of microscopic photosynthetic algae. Since a diatom’s skeleton is made of silica, when it dies it may be preserved in the fossil record. There are many species of diatom, and scientists can often determine their species by studying their tiny fossils, called microfossils. If we find microfossils of species that prefer warmer, sunlit, open waters, we will know the Ross Ice Shelf had melted when these diatoms were alive.

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A response within a system that influences the activity of the system. Positive feedback (self-reinforcing feedback) occurs in a feedback loop* when the effects of a disturbance create an increase in the disturbance. (*A feedback loop is when some or all of the output of a system returns as input.) Negative feedback (balancing feedback) occurs when the output of a system reduces the disturbance and helps stabilize a system to an equilibrium point. Positive feedback usually leads to increased instability, while negative feedback usually leads to stability.

Crystalline or granular snow at an intermediate stage between snow and compaction into glacial ice, and which is especially found on the upper parts of glaciers

A natural substance formed over millions of years from the buried remains of ancient organisms. Fossil fuels include coal, natural gas, and petroleum. Today, humans burn fossil fuels for energy, which releases greenhouse gases into Earth’s atmosphere.

A scientist who studies Earth's physical structure, the substances it is made of, its history and change over time, and the processes that act upon it

When a glacier flows faster than the rate of ablation (mass loss) at its terminus (end)

The continuing movement of land once the glacier that sat upon it has melted. A glacier or ice sheet is extremely heavy, so it pushes down and changes the shape of the land below and around it, just as you deform a mattress when you sit on it. Where you sit, you create an indentation in the mattress, while around you, the mattress rises. When you stand up, the mattress returns to its previous shape. The same is true for land, so when a glacier melts, the land that was below the glacier gradually rises, and the land that rose gradually sinks.

When glacial melt is faster than snow and ice can accumulate

A massive, thick, slow-moving river of ice that flows downhill due to its own weight and the effect of gravity. Glaciers are formed by falling snow over many years, which compacts under the weight of new falling snow and becomes ice. Glaciers consist of snow, ice, and the sediment and rocks they pick up as they flow over the land.

A scientist who studies glaciers and associated aspects such as snow and ice accumulation and changes in glaciers and ice sheets over time

A gas that traps heat in the atmosphere such as carbon dioxide (CO2) or methane (CH4). These gases act like the wall of a glasshouse, stopping heat from the sun from escaping Earth at night.

The thick sheet of ice covering the huge island of Greenland; abbreviated to GrIS

The region where land ice starts to flow off the land onto the sea and float

The geological epoch* that began at the end of the last ice age, around 12,000 years ago. (*An epoch is a unit of geological time.)

International Continental Scientific Drilling Program

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A long time period during which the polar ice caps and alpine (mountain) glaciers expand due to reduced temperatures on the planet’s surface and in its atmosphere. Also called a glacial period. The last ice age ended about 12,000 years ago.

A mass of ice, typically dome-shaped, that rests on bedrock and is elevated above the surrounding ice shelf; it can also be partly surrounded by sea.

An ice sheet is a massive blanket of ice over a large area of land. It forms over thousands to millions of years as snow falls, compacts, and hardens into ice, and it gradually flows down toward the sea. Today, we have two ice sheets, one covering around 80% of Greenland in the Northern Hemisphere and one covering 98% of Antarctica. Together they contain about two thirds of the freshwater on Earth.

An ice shelf is a floating piece of land ice which is attached to the land. Land ice is formed by layers of compacted snow over hundreds and thousands of years. It flows down toward the sea in slow-moving rivers of ice called glaciers and ice streams. When it reaches the sea, it flows off the land and onto the water. Ice is less dense than water, so it floats, just like ice cubes in your drink. Eventually, ice at the edge calves (breaks off) and becomes icebergs. Ice shelves are very important because they act as a buttress (like a wall) and slow the flow of ice sheets.

A region of fast-moving ice within an ice sheet; a type of glacier, a body of ice that moves under its own weight

A large floating mass of ice that has broken off a glacier or ice shelf

The facilities that support modern human life such as roads, buildings, sewer systems, power plants, schools, etc.

A period between ice ages.

A microbe, plant, or animal that lives in the saltwater of the ocean, sea, or coastal estuaries

An ice sheet, such as the West Antarctic Ice Sheet, that sits on bedrock below sea level

Water formed by the melting of snow and ice, particularly glaciers or ice sheets

A microscopic organism, such as a bacterium, that is too small to be seen with the naked eye

A fossil, or a fragment of a fossil, that can only be seen with a microscope

The use of a physical, mathematical, or conceptual representation of an idea, event, object, process, or system. Scientists use models to understand patterns and use them to predict future patterns.

National Science Foundation (USA)

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A continuous movement of seawater in a direction, caused by various forces such as wind, temperature, salinity, the Coriolis Effect, and more. Two ocean currents circle Antarctica: the Antarctic Circumpolar Current, which travels clockwise around the continent, and the Antarctic Coastal Current, which travels anticlockwise and closer to the continent.

In 2015, almost very country on Earth signed the Paris Agreement, a legally binding international treaty on climate change. They agreed to keep warming to below 2 degrees Celsius compared to pre-industrial levels—and preferably to no more than 1.5 degrees Celsius.

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Microscopic marine algae. Like plants, they contain chlorophyll, photosynthesize, and require light to live and grow, so they live in the upper part of the ocean where sunlight can penetrate the water. They also require nutrients such as nitrates, phosphates, and sulphur. They are the base of marine food web and are divided into two main classes, dinoflagellates and diatoms.

Parts per million

The process of drilling into Earth’s sediments, crust, and ice sheets to take samples of sediment, ice, and microfossils for scientists to learn more about Earth in the past.

Frozen seawater, which floats on the ocean’s surface. Sea ice can be found in both Antarctica and the Arctic, and it expands in the cold times of the year and partially melts in the warm months.

The level of the ocean. Since the sea rises and falls with the tides, sea level is taken as the average between mean (average) high and mean low water.

An increase in the level of the world’s oceans due to the effects of climate change, including thermal expansion of the ocean and melting of ice sheets and mountain glaciers. Abbreviated to SLR.

The solid surface at the bottom of the ocean or sea

Material such as rocks, minerals, and the remains of organisms deposited by water, wind, and glaciers

In the context of the SWAIS2C project, sensitivity means 'how sensitive is the West Antarctic Ice Sheet to a warming climate?'

The tendency of a substance (in this case seawater) to change in shape, volume, and area when it is heated. When water gets warmer, its volume increases, so thermal expansion is one of the factors (along with the melting of ice sheets and mountain glaciers) causing sea level rise.

The critical point in a process or system at which a series of small changes becomes significant enough to cause a larger and often unstoppable effect or change.

West Antarctic Ice Sheet; the area of the Antarctic Ice Sheet west of the Transantarctic Mountains