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Antarctic Cold Reversal
The Antarctic Cold Reversal (ACR) was an important episode of cooling in the climate history of the Earth during the deglaciation at the close of the last ice age. It illustrates the complexity of the climate changes at the transition from the Pleistocene to the Holocene Epochs. The Last Glacial Maximum and sea-level minimum occurred c. 21,000 years before present (Before Present, BP). Antarctic ice cores show gradual warming beginning 3,000 years later. At about 14,700 BP, there was a large pulse of meltwater, identified as Meltwater pulse 1A, probably from either the Antarctic ice sheet or the Laurentide Ice Sheet. Meltwater pulse 1A produced a sea-level rise, marine transgression that raised global sea level about 20 meters in two to five centuries and is thought to have influenced the start of the Bølling Oscillation, Bølling/Allerød Oscillation, Allerød interstadial, the major break with glacial cold in the Northern Hemisphere. Meltwater pulse 1A was followed in Antarctica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Climate
Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorological variables that are commonly measured are temperature, humidity, atmospheric pressure, wind, and precipitation. In a broader sense, climate is the state of the components of the climate system, including the atmosphere, hydrosphere, cryosphere, lithosphere and biosphere and the interactions between them. The climate of a location is affected by its latitude/longitude, terrain, altitude, land use and nearby water bodies and their currents. Climates can be classified according to the average and typical variables, most commonly temperature and precipitation. The most widely used classification scheme was the Köppen climate classification. The Thornthwaite system, in use since 1948, incorporates evapotranspiration along with temperature ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bølling Oscillation
The Bølling oscillation, also Bølling interstadial, was a cool temperate climatic interstadial between the glacial Oldest Dryas and Older Dryas stadials, between 14,700 and 14,100 BP, near to the end of the last glacial period. It is named after a peat sequence discovered at Bølling lake in central Jutland, Denmark. It is used to describe a period of time in relation to Pollen zone Ib—in regions where the Older Dryas is not detected in climatological evidence, the Bølling–Allerød is considered a single interstadial period. Dates The beginning of the Bølling is also the high-resolution date for the sharp temperature rise marking the end of the Oldest Dryas at 14,670 BP. Roberts (1998) uses 15,000. A range of 14,650–14,000 BP calibrated has been assigned to the Bølling layer of the excavation at Lake Neuchâtel, Switzerland, 1992–1993. The Oxygen isotope record from Greenland ice includes the Bølling warm peak between 14,600 and 14,100 BP. Most of the recent da ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Climate Of Antarctica
The climate of Antarctica is the Extremes on Earth#Extreme elevations and air temperatures per continent, coldest on Earth. The continent is also extremely dry (it is a desert), averaging of precipitation per year. Snow rarely melts on most parts of the continent, and, after being compressed, becomes the glacier ice that makes up the ice sheet. Weather fronts rarely penetrate far into the continent, because of the katabatic winds. Most of Antarctica has an ice cap climate, ice-cap climate (Köppen climate classification, Köppen classification ''EF'') with very cold, generally extremely dry weather. Temperature The highest temperature ever recorded on Antarctica was recorded at Signy Research Station, Signy Island on 30 January 1982. The highest temperature on the Antarctic mainland was at the Esperanza Base (Argentina) on 6 February 2020. The lowest air temperature record, the Extremes on Earth, lowest reliably measured temperature on Antarctica was set on 21 July 1983, wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Huelmo–Mascardi Cold Reversal
The Huelmo–Mascardi Cold Reversal (HMCR) is a cooling event in South America between 11,400 and 10,200 14C years BP. This cooling began about 550 years before the Younger Dryas cooling in the Northern Hemisphere, and both periods ended at about the same time. The event was given its name from the Huelmo, Chile, and Mascardi Lake, Argentina (Nahuel Huapi National Park Nahuel Huapi National Park () is the oldest national park in Argentina, established in 1934. It surrounds Nahuel Huapi Lake in the foothills of the Patagonian Andes. The largest of the national parks in the region, it has an area of , or nearly ...) sites where it was detected and dated. The HMCR cooling event began with the accentuation of a cooling period which began 12,400 14C yr BP. The 11,400 14C yr BP (13,400 calendar years BP) event onset took place 400–700 years before the onset of the Younger Dryas event. The 10,200 14C yr BP (circa 11,500 cal yr BP) end date is difficult to calibrate to a calen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Southern Ocean
The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica. With a size of , it is regarded as the second-smallest of the five principal oceanic divisions: smaller than the Pacific, Atlantic, and Indian oceans but larger than the Arctic Ocean. Over the past 30 years, the Southern Ocean has been subject to rapid climate change, which has led to changes in the marine ecosystem. By way of his voyages in the 1770s, James Cook proved that waters encompassed the southern latitudes of the globe. Since then, geographers have disagreed on the Southern Ocean's northern boundary or even existence, considering the waters as various parts of the Pacific, Atlantic, and Indian oceans, instead. However, according to Commodore John Leech of the International Hydrographic Organization (IHO), recent oceanographic research has discovered the importance of Southern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Younger Dryas
The Younger Dryas (c. 12,900 to 11,700 years BP) was a return to glacial conditions which temporarily reversed the gradual climatic warming after the Last Glacial Maximum (LGM, c. 27,000 to 20,000 years BP). The Younger Dryas was the last stage of the Pleistocene epoch (c. 2,580,000 to 11,700 years BP) and it preceded the current, warmer Holocene epoch. The Younger Dryas was the most severe and long lasting of several interruptions to the warming of the Earth's climate, and it was preceded by the Late Glacial Interstadial (c. 14,670 to 12,900 BP). The change was relatively sudden, taking place in decades, and it resulted in a decline of temperatures in Greenland by 4~10 °C (7.2~18 °F), and advances of glaciers and drier conditions over much of the temperate Northern Hemisphere. A number of theories have been put forward about the cause, and the most widely supported by scientists is that the Atlantic meridional overturning circulation, which transports warm water fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antarctica
Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest continent, being about 40% larger than Europe, and has an area of . Most of Antarctica is covered by the Antarctic ice sheet, with an average thickness of . Antarctica is, on average, the coldest, driest, and windiest of the continents, and it has the highest average elevation. It is mainly a polar desert, with annual precipitation of over along the coast and far less inland. About 70% of the world's freshwater reserves are frozen in Antarctica, which, if melted, would raise global sea levels by almost . Antarctica holds the record for the lowest measured temperature on Earth, . The coastal regions can reach temperatures over in summer. Native species of animals include mites, nematodes, penguins, seals and tardigrades. Where vegetation o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allerød Oscillation
The Allerød oscillation ( da, Allerødtiden) was a warm and moist global interstadial that occurred c.13,900 to 12,900 BP, nearly at the end of the Last Glacial Period. It raised temperatures in the northern Atlantic region to almost present-day levels, before they declined again in the succeeding glacial Younger Dryas, which was followed by the present warm Holocene. In some regions, especially in northern Eurasia, there is evidence for a cold period known as the Older Dryas interrupting the interstadial. In such regions the shorter oscillation ending with the Older Dryas is known as the Bølling oscillation, and the Allerød period is the interstadial following the Older Dryas. The whole period is called the Bølling–Allerød interstadial. The Allerød period was named after a type site in Furesø Municipality in Sjælland, Denmark (near Copenhagen), where deposits created during the period were first identified in work published in 1901 by Hartz and Milthers. This Bly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sea-level Rise
Globally, sea levels are rising due to human-caused climate change. Between 1901 and 2018, the globally averaged sea level rose by , or 1–2 mm per year on average.IPCC, 2019Summary for Policymakers InIPCC Special Report on the Ocean and Cryosphere in a Changing Climate .-O. Pörtner, D.C. Roberts, V. Masson-Delmotte, P. Zhai, M. Tignor, E. Poloczanska, K. Mintenbeck, A. Alegría, M. Nicolai, A. Okem, J. Petzold, B. Rama, N.M. Weyer (eds.) Cambridge University Press, Cambridge, UK and New York, NY, USA. https://doi.org/10.1017/9781009157964.001. This rate is accelerating, with sea levels now rising by 3.7 mm per year. Climate scientists expect further acceleration during the 21st century. Climate change heats (and therefore expands) the ocean and melts land-based ice sheets and glaciers. Between 1993 and 2018, the thermal expansion of water contributed 42% to sea level rise; melting of temperate glaciers, 21%; Greenland, 15%; and Antarctica, 8%. Over the next 2000 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deglaciation
Deglaciation is the transition from full glacial conditions during ice ages, to warm interglacials, characterized by global warming and sea level rise due to change in continental ice volume. Thus, it refers to the retreat of a glacier, an ice sheet or frozen surface layer, and the resulting exposure of the Earth's surface. The decline of the cryosphere due to ablation can occur on any scale from global to localized to a particular glacier. After the Last Glacial Maximum (ca. 21,000 years ago), the last deglaciation begun, which lasted until the early Holocene. Around much of Earth, deglaciation during the last 100 years has been accelerating as a result of climate change, partly brought on by anthropogenic changes to greenhouse gases. The previous deglaciation took place from approximately 22 ka until 11.5 ka. This occurred when there was an annual mean atmospheric temperature on the earth that increased by roughly 5 °C, which was also accompanied by regional hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laurentide Ice Sheet
The Laurentide Ice Sheet was a massive sheet of ice that covered millions of square miles, including most of Canada and a large portion of the Northern United States, multiple times during the Quaternary glacial epochs, from 2.58 million years ago to the present. The last advance covered most of northern North America between c. 95,000 and c. 20,000 years before the present day and, among other geomorphological effects, gouged out the five Great Lakes and the hosts of smaller lakes of the Canadian Shield. These lakes extend from the eastern Northwest Territories, through most of northern Canada, and the upper Midwestern United States (Minnesota, Wisconsin, and Michigan) to the Finger Lakes, through Lake Champlain and Lake George areas of New York, across the northern Appalachians into and through all of New England and Nova Scotia. At times, the ice sheet's southern margin included the present-day sites of coastal towns of the Northeastern United States, and cities such as Bos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
