|
Multiple Equilibria In The Atlantic Meridional Overturning Circulation
The Atlantic meridional overturning circulation (Atlantic meridional overturning circulation, AMOC) is a large system of ocean currents, like a conveyor belt. It is driven by differences in temperature and salt content and it is an important component of the climate system. However, the AMOC is not a static feature of global circulation. It is sensitive to changes in temperature, salinity and atmospheric forcings. Climate reconstructions from Δ18O, δ18O proxies from Greenland reveal an abrupt transition in global temperature about every 1470 years. These changes may be due to changes in ocean circulation, which suggests that there are two wikt:equilibrium, equilibria possible in the AMOC. Henry Stommel, Stommel made a two-box model in 1961 which showed two different states of the AMOC are possible on a single Hemispheres of Earth, hemisphere. Stommel’s result with an ocean box model has initiated studies using three dimensional Ocean general circulation model, ocean circulation mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atlantic Meridional Overturning Circulation
The Atlantic meridional overturning circulation (AMOC) is part of a global thermohaline circulation in the oceans and is the zonally integrated component of surface and deep currents in the Atlantic Ocean. It is characterized by a northward flow of warm, salty water in the upper layers of the Atlantic, and a southward flow of colder, deep waters. These "limbs" are linked by regions of overturning in the Nordic and Labrador Seas and the Southern Ocean, although the extent of overturning in the Labrador Sea is disputed. The AMOC is an important component of the Earth's climate system, and is a result of both atmospheric and thermohaline drivers. Climate change has the potential to weaken the AMOC through increases in ocean heat content and elevated freshwater flows from the melting ice sheets. Oceanographic reconstructions generally suggest that the AMOC is already weaker than it was before the Industrial Revolution, although there is a robust debate over the role of climate ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Northwestern Europe
Northwestern Europe, or Northwest Europe, is a loosely defined subregion of Europe, overlapping Northern and Western Europe. The region can be defined both geographically and ethnographically. Geographic definitions Geographically, Northwestern Europe usually consists of the United Kingdom, Ireland, Belgium, the Netherlands, Luxembourg, Northern France, Germany, Denmark, Norway, Sweden, and Iceland. Switzerland, Finland, and Austria are also often considered part of Northwestern Europe. Southern France is not regarded as northwestern, as it is usually geographically and culturally considered part of the Mediterranean region or Southern Europe. Ethnographic definitions Germanic languages are widely spoken in most of Northwestern Europe, although other languages are also present, including Romance languages in Northern France, Southern Belgium, Luxembourg, and some parts of Switzerland; Celtic languages along the western fringes of the British Isles and in Brittany; and Ur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hans Oeschger
Hans Oeschger (2 April 1927, Ottenbach – 25 December 1998, Bern) was a Swiss climatologist. He founded the Division of Climate and Environmental Physics at the Physics Institute of the University of Bern in 1963 and was the director until his retirement in 1992. Oeschger was the first to date the "age" of Pacific deep water. The Oeschger counter was the leading instrument for many years which enabled the Oeschger's team to measure the activity of naturally occurring radioisotopes (, , , , , , ). Oeschger was a pioneer and leader in ice core research. In collaboration with his colleagues he was the first to measure the glacial-interglacial change of atmospheric . They showed in 1979 that the atmospheric concentration of during the glacial was almost 50% lower than today. Together with his colleagues Chester C. Langway and Willi Dansgaard, he documented a series of abrupt climate changes in the Greenland ice cores now known as Dansgaard-Oeschger events. Hans Oeschger was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Camp Century
Camp Century was an Arctic United States military scientific research base in Greenland. situated 240 km (150 miles) east of Thule Air Base. When built, Camp Century was publicized as a demonstration for affordable ice-cap military outposts and a base for scientific research. Camp Century was a preliminary camp for Project Iceworm whose end goal was to install a vast network of nuclear missile launch sites that could survive a first strike. This was according to documents declassified in 1996. The missiles were never fielded and necessary consent from the Danish Government to do so was never broached. The camp operated from 1959 until 1967. It consisted of 21 tunnels with a total length of , and was powered by a nuclear reactor. Project Iceworm was aborted after it was realized that the ice sheet was not as stable as originally assessed, and that the missile basing concept would not be feasible. The reactor was removed and Camp Century later abandoned. However, hazardo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Willi Dansgaard
Willi Dansgaard (30 August 1922 – 8 January 2011) was a Danish paleoclimatologist. He was Professor Emeritus of Geophysics at the University of Copenhagen and a member of the Royal Danish Academy of Science and Letters, the Royal Swedish Academy of Sciences, the Icelandic Academy of Sciences, and the Danish Geophysical Society. Early life and career Dansgaard grew up in Copenhagen, to parents who owned an engraving shop. In 1947, he graduated from the University of Copenhagen, winning a gold medal for his thesis on X-ray dosimetry. After several years of research, including some at sites in Greenland, Dansgaard returned to the University of Copenhagen's Biophysics Laboratory, where he developed its mass spectrometer to analyse water isotopes. According to his student Jørgen Peder Steffensen: In June 1952, Dansgaard made a discovery that came to influence the rest of his scientific career. He discovered that it was possible to determine the temperature of the precipi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Dansgaard-Oeschger Cycle
''The'' () is a grammatical article in English, denoting persons or things that are already or about to be mentioned, under discussion, implied or otherwise presumed familiar to listeners, readers, or speakers. It is the definite article in English. ''The'' is the most frequently used word in the English language; studies and analyses of texts have found it to account for seven percent of all printed English-language words. It is derived from gendered articles in Old English which combined in Middle English and now has a single form used with nouns of any gender. The word can be used with both singular and plural nouns, and with a noun that starts with any letter. This is different from many other languages, which have different forms of the definite article for different genders or numbers. Pronunciation In most dialects, "the" is pronounced as (with the voiced dental fricative followed by a schwa) when followed by a consonant sound, and as (homophone of the archaic pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice Sheet
In 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. Masses of ice covering less than 50,000 km2 are termed an ice cap. An ice cap will typically feed a series of glaciers around its periphery. Although the surface is cold, the base of an ice sheet is generally warmer due to geothermal heat. In places, melting occurs and the melt-water lubricates the ice sheet so that it flows more rapidly. This process produces fast-flowing channels in the ice sheet — these are ice streams. The present-day polar ice sheets are relatively you ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greenhouse And Icehouse Earth
Throughout Earth's climate history (Paleoclimate) its climate has fluctuated between two primary states: greenhouse and icehouse Earth. Both climate states last for millions of years and should not be confused with glacial and interglacial periods, which occur as alternate phases within an icehouse period and tend to last less than 1 million years. There are five known Icehouse periods in Earth's climate history, which are known as the Huronian, Cryogenian, Andean-Saharan, Late Paleozoic, and Late Cenozoic glaciations. The main factors involved in changes of the paleoclimate are believed to be the concentration of atmospheric carbon dioxide (), changes in Earth's orbit, long-term changes in the solar constant, and oceanic and orogenic changes from tectonic plate dynamics. Greenhouse and icehouse periods have played key roles in the evolution of life on Earth by directly and indirectly forcing biotic adaptation and turnover at various spatial scales across time. Greenhouse Ea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesozoic
The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Periods. It is characterized by the dominance of archosaurian reptiles, like the dinosaurs; an abundance of conifers and ferns; a hot greenhouse climate; and the tectonic break-up of Pangaea. The Mesozoic is the middle of the three eras since Cambrian explosion, complex life evolved: the Paleozoic, the Mesozoic, and the Cenozoic. The era began in the wake of the Permian–Triassic extinction event, the largest well-documented mass extinction in Earth's history, and ended with the Cretaceous–Paleogene extinction event, another mass extinction whose victims included the non-avian dinosaurs, Pterosaur, pterosaurs, Mosasaur, mosasaurs, and Plesiosaur, plesiosaurs. The Mesozoic was a time of significant tectonic, climatic, and evolut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleozoic
The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ''zōḗ'' (), "life", meaning "ancient life" ). It is the longest of the Phanerozoic eras, lasting from , and is subdivided into six geologic periods (from oldest to youngest): # Cambrian # Ordovician # Silurian # Devonian # Carboniferous # Permian The Paleozoic comes after the Neoproterozoic Era of the Proterozoic Eon and is followed by the Mesozoic Era. The Paleozoic was a time of dramatic geological, climatic, and evolutionary change. The Cambrian witnessed the most rapid and widespread diversification of life in Earth's history, known as the Cambrian explosion, in which most modern phyla first appeared. Arthropods, molluscs, fish, amphibians, reptiles, and synapsids all evolved during the Paleozoic. Life began in the ocean bu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.svg "Click for more on -> Northwestern Europe")
.png "Click for more on -> The Dansgaard-Oeschger Cycle")
