Ice coreAn ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier. Since the ice forms from the incremental buildup of annual layers of snow, lower layers are older than upper ones, and an ice core contains ice formed over a range of years. Cores are drilled with hand augers (for shallow holes) or powered drills; they can reach depths of over two miles (3.2 km), and contain ice up to 800,000 years old. The physical properties of the ice and of material trapped in it can be used to reconstruct the climate over the age range of the core.
Ice sheetIn glaciology, an ice sheet, also known as a continental glacier, is a mass of glacial ice that covers surrounding terrain and is greater than . The only current ice sheets are in Antarctica and Greenland; during the Last Glacial Period at Last Glacial Maximum, the Laurentide Ice Sheet covered much of North America, the Weichselian ice sheet covered Northern Europe and the Patagonian Ice Sheet covered southern South America. Ice sheets are bigger than ice shelves or alpine glaciers.
Greenland ice sheetThe Greenland ice sheet (Grønlands indlandsis, Sermersuaq) is a vast body of ice covering , roughly near 80% of the surface of Greenland. It is sometimes referred to as an ice cap, or under the term inland ice, or its Danish equivalent, indlandsis. The acronym GIS is frequently used in the scientific literature. It is the second largest ice body in the world, after the Antarctic ice sheet. The ice sheet is almost long in a north–south direction, and its greatest width is at a latitude of 77°N, near its northern margin.
Ice-sheet modelIn climate modelling, Ice-sheet models use numerical methods to simulate the evolution, dynamics and thermodynamics of ice sheets, such as the Greenland ice sheet, the Antarctic ice sheet or the large ice sheets on the northern hemisphere during the last glacial period. They are used for a variety of purposes, from studies of the glaciation of Earth over glacial–interglacial cycles in the past to projections of ice-sheet decay under future global warming conditions. Beginning in the mid-18th Century, investigation into ice sheet behavior began.
Antarctic ice sheetThe Antarctic ice sheet is one of the two polar ice caps of Earth. It covers about 98% of the Antarctic continent and is the largest single mass of ice on Earth, with an average thickness of over 2 kilometers. Separate to the Antarctic sea ice it covers an area of almost and contains of ice. A cubic kilometer of ice weighs approximately 0.92 metric gigatonnes, meaning that the ice sheet weighs about 24,380,000 gigatonnes. It holds approximately 61% of all fresh water on Earth, equivalent to about 58 meters of sea level rise if all the ice were above sea level.
SnowSnow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes. It consists of frozen crystalline water throughout its life cycle, starting when, under suitable conditions, the ice crystals form in the atmosphere, increase to millimeter size, precipitate and accumulate on surfaces, then metamorphose in place, and ultimately melt, slide or sublimate away.
Sea iceSea ice arises as seawater freezes. Because ice is less dense than water, it floats on the ocean's surface (as does fresh water ice, which has an even lower density). Sea ice covers about 7% of the Earth's surface and about 12% of the world's oceans. Much of the world's sea ice is enclosed within the polar ice packs in the Earth's polar regions: the Arctic ice pack of the Arctic Ocean and the Antarctic ice pack of the Southern Ocean.
IceIce is water frozen into a solid state, typically forming at or below temperatures of 32 °F, 0 °C, or 273.15 K. Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opaque bluish-white color. In the Solar System, ice is abundant and occurs naturally from as close to the Sun as Mercury to as far away as the Oort cloud objects. Beyond the Solar System, it occurs as interstellar ice.
Glacier mass balanceCrucial to the survival of a glacier is its mass balance of which surface mass balance (SMB), the difference between accumulation and ablation (sublimation and melting). Climate change may cause variations in both temperature and snowfall, causing changes in the surface mass balance. Changes in mass balance control a glacier's long-term behavior and are the most sensitive climate indicators on a glacier. From 1980 to 2012 the mean cumulative mass loss of glaciers reporting mass balance to the World Glacier Monitoring Service is −16 m.
GlacierA glacier (USpronˈɡleɪʃər; UKˈɡlæsiər,_ˈgleɪsiər) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as crevasses and seracs, as it slowly flows and deforms under stresses induced by its weight. As it moves, it abrades rock and debris from its substrate to create landforms such as cirques, moraines, or fjords.
Polar ice capA polar ice cap or polar cap is a high-latitude region of a planet, dwarf planet, or natural satellite that is covered in ice. There are no requirements with respect to size or composition for a body of ice to be termed a polar ice cap, nor any geological requirement for it to be over land, but only that it must be a body of solid phase matter in the polar region. This causes the term "polar ice cap" to be something of a misnomer, as the term ice cap itself is applied more narrowly to bodies that are over land, and cover less than 50,000 km2: larger bodies are referred to as ice sheets.
Glacier ice accumulationGlacier ice accumulation occurs through accumulation of snow and other frozen precipitation, as well as through other means including rime ice (freezing of water vapor on the glacier surface), avalanching from hanging glaciers on cliffs and mountainsides above, and re-freezing of glacier meltwater as superimposed ice. Accumulation is one element in the glacier mass balance formula, with ablation counteracting. With successive years in which accumulation exceeds ablation, then a glacier will experience positive mass balance, and its terminus will advance.
PermafrostPermafrost () is soil or underwater sediment which continuously remains below for two or more years. Land-based permafrost can include the surface layer of the soil, but if the surface is too warm, it may still occur within a few centimeters of the surface down to hundreds of meters. It usually consists of ice holding in place a combination of various types of soil, sand, and rock, though in ice-free ground, perennially frozen non-porous bedrock can serve the same role.
Weather stationA weather station is a facility, either on land or sea, with instruments and equipment for measuring atmospheric conditions to provide information for weather forecasts and to study the weather and climate. The measurements taken include temperature, atmospheric pressure, humidity, wind speed, wind direction, and precipitation amounts. Wind measurements are taken with as few other obstructions as possible, while temperature and humidity measurements are kept free from direct solar radiation, or insolation.
Climate changeIn common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to Earth's climate. The current rise in global average temperature is more rapid than previous changes, and is primarily caused by humans burning fossil fuels. Fossil fuel use, deforestation, and some agricultural and industrial practices increase greenhouse gases, notably carbon dioxide and methane.
Automatic weather stationAn automatic weather station (AWS) is an automated version of the traditional weather station, either to save human labor or to enable measurements from remote areas. An AWS will typically consist of a weather-proof enclosure containing the data logger, rechargeable battery, telemetry (optional) and the meteorological sensors with an attached solar panel or wind turbine and mounted upon a mast. The specific configuration may vary due to the purpose of the system.
SnowpackSnowpack forms from layers of snow that accumulate in geographic regions and high elevations where the climate includes cold weather for extended periods during the year. Snowpacks are an important water resource that feed streams and rivers as they melt. Therefore, snowpacks are both the drinking water source for many communities and a potential source of flooding (in case of sudden melting). Snowpacks also contribute mass to glaciers in their accumulation zone.
Automated airport weather stationAirport weather stations are automated sensor suites which are designed to serve aviation and meteorological operations, weather forecasting and climatology. Automated airport weather stations have become part of the backbone of weather observing in the United States and Canada and are becoming increasingly more prevalent worldwide due to their efficiency and cost-savings. In the United States, there are several varieties of automated weather stations that have somewhat subtle but important differences.
MeltwaterMeltwater (or melt water) is water released by the melting of snow or ice, including glacial ice, tabular icebergs and ice shelves over oceans. Meltwater is often found during early spring when snow packs and frozen rivers melt with rising temperatures, and in the ablation zone of glaciers where the rate of snow cover is reducing. Meltwater can be produced during volcanic eruptions, in a similar way in which the more dangerous lahars form. When meltwater pools on the surface rather than flowing, it forms melt ponds.
GreenlandGreenland (Kalaallit Nunaat, kalaːɬːit nʉnaːt; Grønland, ˈkʁɶnˌlænˀ) is a North American autonomous territory in the Kingdom of Denmark. It is one of three countries that form the Kingdom, the others being Denmark proper and the Faroe Islands; the citizens of all three countries are citizens of Denmark and the European Union. The capital and largest city of Greenland is Nuuk. Greenland lies between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago.
