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123-417: After the retreat of the ice sheet that covered the region after the last ice age , the river found itself rerouted by an esker onto a plain uniquely ribbed by the ridges of other eskers, where it formed a succession of rapids and wide bays (called fjärdar ), which the river inundates during the spring floods. This particular hydrography , along with the park's proximity to the ecological frontier between

246-487: A climate change feedback if it is gradually released through meltwater, thus increasing overall carbon dioxide emissions . For comparison, 1400–1650 billion tonnes are contained within the Arctic permafrost . Also for comparison, the annual human caused carbon dioxide emissions amount to around 40 billion tonnes of CO 2 . In Greenland, there is one known area, at Russell Glacier , where meltwater carbon

369-518: A continental glacier , is a mass of glacial ice that covers surrounding terrain and is greater than 50,000 km (19,000 sq mi). The only current ice sheets are the Antarctic ice sheet and the Greenland ice sheet . Ice sheets are bigger than ice shelves or alpine glaciers . Masses of ice covering less than 50,000 km are termed an ice cap . An ice cap will typically feed

492-581: A 1 m tidal oscillation can be felt as much as 100 km from the sea. During larger spring tides , an ice stream will remain almost stationary for hours at a time, before a surge of around a foot in under an hour, just after the peak high tide; a stationary period then takes hold until another surge towards the middle or end of the falling tide. At neap tides, this interaction is less pronounced, and surges instead occur approximately every 12 hours. Increasing global air temperatures due to climate change take around 10,000 years to directly propagate through

615-425: A buttressing effect on the ice sheet, the so-called back stress increases and the grounding line is pushed backwards. The ice sheet is likely to start losing more ice from the new location of the grounding line and so become lighter and less capable of displacing seawater. This eventually pushes the grounding line back even further, creating a self-reinforcing mechanism . Because the entire West Antarctic Ice Sheet

738-514: A combined area, with the park and peninsula reserves, of more than 3,000 ha (7,400 acres). The terrain of the park is overall flat, with an altitude ranging from 56 m (184 ft) to 75 m (246 ft) below sea level. Certain parts are nevertheless quite hilly, such as Torrösundet, Långvindsjön and the valleys of the Tiån and the Storån. In addition, the ridge Enköpingsåsen cuts across

861-426: A higher level of warming. Isostatic rebound of ice-free land may also add around 1 m (3 ft 3 in) to the global sea levels over another 1,000 years. The East Antarctic Ice Sheet (EAIS) lies between 45° west and 168° east longitudinally. It was first formed around 34 million years ago, and it is the largest ice sheet on the entire planet, with far greater volume than the Greenland ice sheet or

984-685: A large number of tourists each year and the Board of Tourism in Södermanland estimates that a little less than 250,000 people from all over the world pass through the town each year. About 733,650 days AD, Trosa celebrated 146,000 days as a town at its present location under the motto "Future since 1610". The metalcore band Adept (band) is from the town. Within Trosa locality there are four elementary schools (grades 1–6), two junior high schools (grades 7–9). Right now there are no plans to build or house

1107-614: A little over 3 months and the river is frozen during a similar period, with the exception of the rapids, which remain ice-free for most of the winter. The park is situated along the course of the Dalälven , the second longest Swedish river at 541 km (336 mi). The river begins at the confluence of the Västerdal River and the Österdal River in Gagnef Municipality . At Avesta, the river, which until then

1230-432: A much greater area than this minimum definition, measuring at 1.7 million km and 14 million km , respectively. Both ice sheets are also very thick, as they consist of a continuous ice layer with an average thickness of 2 km (1 mi). This ice layer forms because most of the snow which falls onto the ice sheet never melts, and is instead compressed by the mass of newer snow layers. This process of ice sheet growth

1353-525: A new couple in 2010. This species especially likes old forests with many dead trees and the species is thus a good indicator of the richness of the forest. In contrast, the grey-headed woodpecker is becoming more common. Regarding owls, the most common species are the Eurasian pygmy owl and the Ural owl . The latter is in addition the symbol of the park. Apart from these species, there are the common buzzard ,

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1476-483: A park is approved, the state buys the land, through the intermediary of the Naturvårdsverket. The management of the park is then principally in the hands of the county. Despite the fact that the park of Färnebofjärden spans the territories of four counties, only the administrative council of Västmanland is responsible for the management of the park. In contrast, park's nature center is led by Gävleborg, since it

1599-705: A portion of the ice sheet collapses. External factors might also play a role in forcing ice sheets. Dansgaard–Oeschger events are abrupt warmings of the northern hemisphere occurring over the space of perhaps 40 years. While these D–O events occur directly after each Heinrich event, they also occur more frequently – around every 1500 years; from this evidence, paleoclimatologists surmise that the same forcings may drive both Heinrich and D–O events. Hemispheric asynchrony in ice sheet behavior has been observed by linking short-term spikes of methane in Greenland ice cores and Antarctic ice cores. During Dansgaard–Oeschger events ,

1722-571: A relatively intact state". It thus includes a large part of the old reserve of Gysinge, which accordingly was reformed in 1999 with all the zones not included in the park. On 19   November 2001, the park was finally added to the Ramsar list. It is also included in the Natura 2000 Network. In 2011, the Lower Dalälven was classified as a biosphere reserve by UNESCO under the name country of

1845-427: A rich population of aquatic birds, attracted by the shallow, fish-rich waters. The proximity of big trees, especially pines, affords them good nesting opportunities. The most common species are the common gull , the common tern , the black-throated loon , and the mute swan . In the wetlands, one often finds the grey heron , the western capercaillie or even the common crane . One of the most notable aquatic species

1968-430: 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 . Even stable ice sheets are continually in motion as the ice gradually flows outward from

2091-460: A shallow fjord and stabilized) could have involved MICI, but there weren't enough observations to confirm or refute this theory. The retreat of Greenland ice sheet 's three largest glaciers - Jakobshavn , Helheim , and Kangerdlugssuaq Glacier - did not resemble predictions from ice cliff collapse at least up until the end of 2013, but an event observed at Helheim Glacier in August 2014 may fit

2214-482: A third of the non-aquatic surface area of the park. The bedrock of the park is of granite and granitic gneiss , and dates from the formation of the Svecofennids, a mountain chain formed between 1750 and 2500 million years ago. Subsequently, the area underwent a long period of erosion , so that by leading 600 million years ago the so-called Sub-Cambrian peneplain had formed. During the last ice age , Sweden

2337-407: A worst-case of about 33 cm (13 in). For comparison, melting has so far contributed 1.4 cm ( 1 ⁄ 2  in) since 1972, while sea level rise from all sources was 15–25 cm (6–10 in) between 1901 and 2018. Historically, ice sheets were viewed as inert components of the carbon cycle and were largely disregarded in global models. In 2010s, research had demonstrated

2460-409: Is about 1 million years old. Due to anthropogenic greenhouse gas emissions , the ice sheet is now the warmest it has been in the past 1000 years, and is losing ice at the fastest rate in at least the past 12,000 years. Every summer, parts of the surface melt and ice cliffs calve into the sea. Normally the ice sheet would be replenished by winter snowfall, but due to global warming the ice sheet

2583-404: Is about 77 km (48 mi) from the city of Uppsala and so about 140 km (87 mi) from Stockholm . The park proper includes most of the fjärd of Färnebofjärden and the river's floodplain, as well as parts of the surrounding lowlands, for a total area of more than 10,100 ha (25,000 acres), of which 4,110 ha (10,200 acres) are water. The only parts of the fjärd not included in

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2706-517: Is also possible to stay at Gysinge forge's hotel ( Gysinge bruk Wärdshus ). Inside the park itself, many cabins are available for passing the night, many of them ancient shepherd cabins. The principal activities inside the park in summer are sport fishing as well as boat or canoe trips. Navigation by boat is in fact one of the best ways to explore the park, and the island of Sandön is particularly popular. The park also attracts many bird watchers in winter and spring, especially near Tinäset where

2829-456: Is believed that the loss of the ice sheet would take place between 2,000 and 13,000 years in the future, although several centuries of high emissions may shorten this to 500 years. 3.3 m (10 ft 10 in) of sea level rise would occur if the ice sheet collapses but leaves ice caps on the mountains behind. Total sea level rise from West Antarctica increases to 4.3 m (14 ft 1 in) if they melt as well, but this would require

2952-495: Is colloquially nicknamed Världens ände ("The world's end", specifically the rear end , as "Trosa" is coincidentally also Swedish for " panty "). The municipality of Trosa consists of the three towns Trosa, Västerljung and Vagnhärad. Despite its small size, Trosa states its place in Sweden. It is the second fastest growing town in Sweden (2,9%/year 2008) and is ranked as having the 3rd best business climate in Sweden (2011). Trosa

3075-504: Is equally appreciated by fishing enthusiasts. The park takes its name from Färnebofjärden, which designates the entire section of the river between Tyttbo and Gysinge. The name means "fjärd of Färnebo". The Swedish word fjärd has the same etymology as the Norwegian word fjord, both of which Scandinavian words mean "an expanse of water in a channel". Most of the bodies of water called fjords in Norwegian were steep glacial valleys into which

3198-468: Is evidence of large glaciers in Greenland for most of the past 18 million years, these ice bodies were probably similar to various smaller modern examples, such as Maniitsoq and Flade Isblink , which cover 76,000 and 100,000 square kilometres (29,000 and 39,000 sq mi) around the periphery. Conditions in Greenland were not initially suitable for a single coherent ice sheet to develop, but this began to change around 10 million years ago , during

3321-483: Is grounded below the sea level, it would be vulnerable to geologically rapid ice loss in this scenario. In particular, the Thwaites and Pine Island glaciers are most likely to be prone to MISI, and both glaciers have been rapidly thinning and accelerating in recent decades. As the result, sea level rise from the ice sheet could be accelerated by tens of centimeters within the 21st century alone. The majority of

3444-724: Is known to vary on seasonal to interannual timescales. The Wilkes Basin is the only major submarine basin in Antarctica that is not thought to be sensitive to warming. Ultimately, even geologically rapid sea level rise would still most likely require several millennia for the entirety of these ice masses (WAIS and the subglacial basins) to be lost. A related process known as Marine Ice Cliff Instability (MICI) posits that ice cliffs which exceed ~ 90 m ( 295 + 1 ⁄ 2  ft) in above-ground height and are ~ 800 m ( 2,624 + 1 ⁄ 2  ft) in basal (underground) height are likely to collapse under their own weight once

3567-501: Is melting two to five times faster than before 1850, and snowfall has not kept up since 1996. If the Paris Agreement goal of staying below 2 °C (3.6 °F) is achieved, melting of Greenland ice alone would still add around 6 cm ( 2 + 1 ⁄ 2  in) to global sea level rise by the end of the century. If there are no reductions in emissions, melting would add around 13 cm (5 in) by 2100, with

3690-465: Is often covered in peat mosses and other mosses . The park is host to many species of mammals . The most widespread are the moose , the roe deer , the mountain hare , the red fox , and the European pine marten . Since the 1980s, one can also see Eurasian beaver near the islands of Torrön and Ängsön as well as near Gysinge. In 2008, it was similarly found that the wild boar was wont to settle

3813-487: Is released into the atmosphere as methane , which has a much larger global warming potential than carbon dioxide. However, it also harbours large numbers of methanotrophic bacteria, which limit those emissions. Normally, the transitions between glacial and interglacial states are governed by Milankovitch cycles , which are patterns in insolation (the amount of sunlight reaching the Earth). These patterns are caused by

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3936-464: Is situated on Gävleborg's territory. The management work for the park includes the maintenance of tourism structures (such as trails, cabins), as well as the maintenance of certain meadows. If appropriate, the park authorities can regulate the beaver population, which is capable of harming the forest. Elk, deer, and American mink hunting is allowed for population regulation purposes, but is forbidden between 1   January and 15   August. To protect

4059-484: Is still occurring nowadays, as can be clearly seen in an example that occurred in World War II . A Lockheed P-38 Lightning fighter plane crashed in Greenland in 1942. It was only recovered 50 years later. By then, it had been buried under 81 m (268 feet) of ice which had formed over that time period. Even stable ice sheets are continually in motion as the ice gradually flows outward from the central plateau, which

4182-524: Is still open for debate. The icing of Antarctica began in the Late Palaeocene or middle Eocene between 60 and 45.5 million years ago and escalated during the Eocene–Oligocene extinction event about 34 million years ago. CO 2 levels were then about 760 ppm and had been decreasing from earlier levels in the thousands of ppm. Carbon dioxide decrease, with a tipping point of 600 ppm,

4305-420: Is the osprey , with thirty couples — probably one of the most important densities of the country. The white-tailed eagle , a species classified as endangered in the country, practically vanished from the park in the 1970s, but it is now returned. However, it is the forest species which are the most notable of the park, especially the woodpeckers and owls . Concerning woodpeckers, the great spotted woodpecker

4428-401: Is the most common, but the black woodpecker , the European green woodpecker and the lesser spotted woodpecker are also themselves common. The population of white-backed woodpecker , a species classified as very endangered in Sweden with only 16 individuals in the whole country in 2004, has diminished in the park. Of 7 pairs observed in 1976, one sole individual was observed in 2003, and then

4551-707: Is the segment of the continental ice sheet that covers West Antarctica , the portion of Antarctica on the side of the Transantarctic Mountains that lies in the Western Hemisphere . It is classified as a marine-based ice sheet, meaning that its bed lies well below sea level and its edges flow into floating ice shelves. The WAIS is bounded by the Ross Ice Shelf , the Ronne Ice Shelf , and outlet glaciers that drain into

4674-456: Is the tallest point of the ice sheet, and towards the margins. The ice sheet slope is low around the plateau but increases steeply at the margins. This difference in slope occurs due to an imbalance between high ice accumulation in the central plateau and lower accumulation, as well as higher ablation , at the margins. This imbalance increases the shear stress on a glacier until it begins to flow. The flow velocity and deformation will increase as

4797-512: The Amundsen Sea . As a smaller part of Antarctica, WAIS is also more strongly affected by climate change . There has been warming over the ice sheet since the 1950s, and a substantial retreat of its coastal glaciers since at least the 1990s. Estimates suggest it added around 7.6 ± 3.9 mm ( 19 ⁄ 64  ±  5 ⁄ 32  in) to the global sea level rise between 1992 and 2017, and has been losing ice in

4920-414: The Eurasian hobby , or even, among others, the European honey buzzard . The park has all major Swedish species of amphibians . Among these species, one can number the common toad , the common frog and the moor frog , as well as the northern crested newt and the smooth newt . Among the reptiles , the most common species are two snakes , the common European adder and the grass snake , as well as

5043-713: The Last Glacial Period at Last Glacial Maximum , the Laurentide Ice Sheet covered much of North America . In the same period, the Weichselian ice sheet covered Northern Europe and the Patagonian Ice Sheet covered southern South America . An ice sheet is a body of ice which covers a land area of continental size - meaning that it exceeds 50,000 km . The currently existing two ice sheets in Greenland and Antarctica have

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5166-520: The Swedish royal family , Mikael Persbrandt , ABBAs Benny Andersson and Björn Ulvaeus . The founder of Camfil Farr , Gösta Larsson, lived in Trosa all of his life and at the moment the Larsson-Markman family runs the company. The general number of people living in Trosa goes up by 131% during the summer months of June–August because of the high ratio of summer residences. Trosa brings in

5289-644: The West Antarctic Ice Sheet (WAIS), from which it is separated by the Transantarctic Mountains . The ice sheet is around 2.2 km (1.4 mi) thick on average and is 4,897 m (16,066 ft) at its thickest point. It is also home to the geographic South Pole , South Magnetic Pole and the Amundsen–Scott South Pole Station . The surface of the EAIS is the driest, windiest, and coldest place on Earth. Lack of moisture in

5412-551: The Younger Dryas period which appears consistent with MICI. However, it indicates "relatively rapid" yet still prolonged ice sheet retreat, with a movement of >200 km (120 mi) inland taking place over an estimated 1100 years (from ~12,300 years Before Present to ~11,200 B.P.) In recent years, 2002-2004 fast retreat of Crane Glacier immediately after the collapse of the Larsen B ice shelf (before it reached

5535-558: The brown trout . The Atlantic salmon was also present in the park's waters, but the dams downstream have considerably reduced its possibilities of rejoining the park. The noble crayfish , a species endangered worldwide, was relatively common in the waters of the Dalälven, but has now almost disappeared; some catches in the park are however reported from time to time. Only the insects of the forests have been reliably inventoried, but more than 70 species of insect are already inscribed on

5658-447: The viviparous lizard and the slowworm . The waters of the park are among Sweden's richest, which can be explained by a great number of factors, such as their optimal acidity , a great richness of nutrients, or even, among other things, the zones of rapids alternating with calmer zones. These waters permit the park have not only a great number of species, but also a great number of individual fish and certain fish of enormous size. Among

5781-555: The 2010s at a rate equivalent to 0.4 millimetres (0.016 inches) of annual sea level rise. While some of its losses are offset by the growth of the East Antarctic ice sheet , Antarctica as a whole will most likely lose enough ice by 2100 to add 11 cm (4.3 in) to sea levels. Further, marine ice sheet instability may increase this amount by tens of centimeters, particularly under high warming. Fresh meltwater from WAIS also contributes to ocean stratification and dilutes

5904-502: The Antarctic winter is cooler at the surface than in its middle layers. Consequently, greenhouse gases actually trap heat in the middle atmosphere and reduce its flow towards the surface while the temperature inversion lasts. Due to these factors, East Antarctica had experienced slight cooling for decades while the rest of the world warmed as the result of climate change . Clear warming over East Antarctica only started to occur since

6027-510: The East Antarctic Ice Sheet would not be affected. Totten Glacier is the largest glacier there which is known to be subject to MISI - yet, its potential contribution to sea level rise is comparable to that of the entire West Antarctic Ice Sheet. Totten Glacier has been losing mass nearly monotonically in recent decades, suggesting rapid retreat is possible in the near future, although the dynamic behavior of Totten Ice Shelf

6150-559: The Lillån, the Storån, the Alderbäcken and the Tiån on the right (south) bank, and Bärreksån and Laggarboån along the right bank. One can find also five small lakes inside the park, in particular around Tinäset. It is also near Tinäset that the principal bogs of the park, Lindebergsmossen and Svarviksmossen, are situated. 2,150 ha (5,300 acres) of the park are marshes and bogs, making up more than 20% of its total surface, and more than

6273-656: The SLR was greater than 6 m ( 19 + 1 ⁄ 2  ft). As of 2023, the most recent analysis indicates that the Last Interglacial SLR is unlikely to have been higher than 2.7 m (9 ft), as higher values in other research, such as 5.7 m ( 18 + 1 ⁄ 2  ft), appear inconsistent with the new paleoclimate data from The Bahamas and the known history of the Greenland Ice Sheet. The West Antarctic Ice Sheet (WAIS)

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6396-412: The air, high albedo from the snow as well as the surface's consistently high elevation results in the reported cold temperature records of nearly −100 °C (−148 °F). It is the only place on Earth cold enough for atmospheric temperature inversion to occur consistently. That is, while the atmosphere is typically warmest near the surface and becomes cooler at greater elevation, atmosphere during

6519-527: The ancestor of the Baltic Sea , withdrew, the Dalälven found itself blocked at Avesta by one of these eskers formed by the ice sheet: Badelundaåsen. In effect, before the ice age, the river continued in the direction of the Mälaren , in which it emptied itself and it so had flooded a valley along this entire section. Because of the fact of the presence of this obstacle, it was forced to head northeast. So, in

6642-419: The baltic fishery during the 1870s diminished in economic terms, the city opted for tourism as a business for the small coastal city. Today Trosa is one of the top four wealthiest communities in Sweden (32% of the population earns more than 1,5 million SEK a year). Many famous people have summerhouses in or close to Trosa, for example the well-known chef, hunter and actor Per Morberg as well as Tommy Körberg ,

6765-416: The base of the glacier in as little as 2–18 hours – lubricating the bed and causing the glacier to surge . Water that reaches the bed of a glacier may freeze there, increasing the thickness of the glacier by pushing it up from below. As the margins end at the marine boundary, excess ice is discharged through ice streams or outlet glaciers . Then, it either falls directly into the sea or is accumulated atop

6888-532: The bedrock, which explains why that region even today has superior fertility to that of the rest of the country. It is the reason why the line of separation between the north and the south (the Limes Norrlandicus ), which passes not far from the park, is so visible in the region: the zone to the north of the limes was not covered with these sediments. When this sea, called the Littorina Sea ,

7011-492: The beginning of the 20th century. One of the characteristics of the region that has strongly influenced the mode of life there ever since the Iron Age is its abundance of metals, in particular of iron . The settlers began then to combine agriculture with iron extraction. This exploitation has left numerous traces inside the park. Certain zones in the park were themselves used as extraction sites, such as Tinäset, where limonite

7134-500: The birdlife is the richest. However, the part of the road that enabled one to get there was closed because it traversed the park — which closing was decided during the park's creation. As a result, the number of tourists at this location diminished considerably. A visitor, information, and nature center was built inside an old barn (dating from 1814) of the Gysinge forge. At Skekarsbo, an observation tower 20 metres (66 ft) in height

7257-447: The birds, access to certain zones can be forbidden during nesting season, from 1   January to 15   June. These fixed zones have been replaced in 2015 by the possibility of creating temporary zones permitting themselves to adapt to zones where the most vulnerable species are found. The ban on commercial activity has also been lifted. Finally, the speed limit for boats was lowered from 12 to 7 knots except for certain sections where

7380-427: The boulders and other continental rocks they carried, leaving layers known as ice rafted debris . These so-called Heinrich events , named after their discoverer Hartmut Heinrich , appear to have a 7,000–10,000-year periodicity , and occur during cold periods within the last interglacial. Internal ice sheet "binge-purge" cycles may be responsible for the observed effects, where the ice builds to unstable levels, then

7503-604: The central plateau, which is the tallest point of the ice sheet, and towards the margins. The ice sheet slope is low around the plateau but increases steeply at the margins. Increasing global air temperatures due to climate change take around 10,000 years to directly propagate through the ice before they influence bed temperatures, but may have an effect through increased surface melting, producing more supraglacial lakes . These lakes may feed warm water to glacial bases and facilitate glacial motion. In previous geologic time spans ( glacial periods ) there were other ice sheets. During

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7626-402: The collapse of Larsen B, in context. In the 1970s, Johannes Weertman proposed that because seawater is denser than ice, then any ice sheets grounded below sea level inherently become less stable as they melt due to Archimedes' principle . Effectively, these marine ice sheets must have enough mass to exceed the mass of the seawater displaced by the ice, which requires excess thickness. As

7749-515: The continent since the 1957. The Greenland ice sheet is an ice sheet which forms the second largest body of ice in the world. It is an average of 1.67 km (1.0 mi) thick, and over 3 km (1.9 mi) thick at its maximum. It is almost 2,900 kilometres (1,800 mi) long in a north–south direction, with a maximum width of 1,100 kilometres (680 mi) at a latitude of 77°N , near its northern edge. The ice sheet covers 1,710,000 square kilometres (660,000 sq mi), around 80% of

7872-479: The creation of national parks established by Naturvårdsverket, Färnebofjärden was proposed as a future national park. In 1997, Färnebofjärden is proposed on the list of the Ramsar Convention , and, finally, the national park was established by the king on 10   September 1998. The motive for creating the park was "to preserve a unique fluvial landscape as well as rich forests and surrounding wetlands in

7995-505: The definition. Further, modelling done after the initial hypothesis indicates that ice-cliff instability would require implausibly fast ice shelf collapse (i.e. within an hour for ~ 90 m ( 295 + 1 ⁄ 2  ft)-tall cliffs), unless the ice had already been substantially damaged beforehand. Further, ice cliff breakdown would produce a large number of debris in the coastal waters - known as ice mélange - and multiple studies indicate their build-up would slow or even outright stop

8118-522: The equilibrium line between these two processes is approached. This motion is driven by gravity but is controlled by temperature and the strength of individual glacier bases. A number of processes alter these two factors, resulting in cyclic surges of activity interspersed with longer periods of inactivity, on time scales ranging from hourly (i.e. tidal flows) to the centennial (Milankovich cycles). On an unrelated hour-to-hour basis, surges of ice motion can be modulated by tidal activity. The influence of

8241-568: The eskers. Among the park's prehistoric sites, one can count the Stone Age sites at Trångnäs and Sandön and the cairns atop Hemön and Utön. When sedentary agriculture developed in the region during the Bronze and Iron Ages, the slopes of the crests were again the favorite settlement sites, being easier to cultivate and above the floodplain. However, these wetlands were also used for haymaking, giving an important production of good quality. The hay

8364-498: The existence of uniquely adapted microbial communities , high rates of biogeochemical and physical weathering in ice sheets, and storage and cycling of organic carbon in excess of 100 billion tonnes. There is a massive contrast in carbon storage between the two ice sheets. While only about 0.5-27 billion tonnes of pure carbon are present underneath the Greenland ice sheet, 6000-21,000 billion tonnes of pure carbon are thought to be located underneath Antarctica. This carbon can act as

8487-787: The fjärd of horsetails ( fräken , which became Färne)". The park straddles the municipalities of Sala in Västmanland County , Heby in Uppsala County , Avesta in Dalarna County , and Sandviken in Gävleborg County . It contains a section of the Lower Dalälven , which since the Middle Ages has marked the frontier between Svealand and Norrland . The park's main entrance, at Gysinge,

8610-406: The floating ice shelves . Those ice shelves then calve icebergs at their periphery if they experience excess of ice. Ice shelves would also experience accelerated calving due to basal melting. In Antarctica, this is driven by heat fed to the shelf by the circumpolar deep water current, which is 3 °C above the ice's melting point. The presence of ice shelves has a stabilizing influence on

8733-470: The flow of the river Österdalälven is controlled (at Trängslet and the lake Siljan ), the course of the Västerdalälven is free, and thus has the largest seasonal variations. As a result, when it reaches the park, the river is still relatively little regulated, with a speed varying from 50 m/s (1,800 cu ft/s) to more than 2,000 m/s (71,000 cu ft/s). It is, in particular,

8856-413: The formation of a proposition for a national park in 1975. Only the commune of Sandviken took up the idea and formed the same year the nature reserve of Gysinge. In the following years, the geomorphology, fauna and flora of the Lower Dalälven were systematically inventoried. This began at the formulation of a protection plan by Naturvårdsverket and the concerned counties. In 1989, in the first directive for

8979-528: The formation of salty Antarctic bottom water , which destabilizes Southern Ocean overturning circulation . In the long term, the West Antarctic Ice Sheet is likely to disappear due to the warming which has already occurred. Paleoclimate evidence suggests that this has already happened during the Eemian period, when the global temperatures were similar to the early 21st century. It

9102-454: The genus Aedes . Indeed, the park's wetlands are enormously productive in mosquitos, especially during the heavy spring floods. The quantity of mosquitos in the Lower Dalälven has no equivalent in Sweden besides that in the vast wetlands of Lappland . This abundance bothers not only the park's tourists during the summer but also the entire region as far as Uppsala . Between 2002 and 2008, the insecticide Bacillus thuringiensis israelensis

9225-529: The glacier behind them, while an absence of an ice shelf becomes destabilizing. For instance, when Larsen B ice shelf in the Antarctic Peninsula had collapsed over three weeks in February 2002, the four glaciers behind it - Crane Glacier , Green Glacier , Hektoria Glacier and Jorum Glacier - all started to flow at a much faster rate, while the two glaciers (Flask and Leppard) stabilized by

9348-437: The ice before they influence bed temperatures, but may have an effect through increased surface melting, producing more supraglacial lakes . These lakes may feed warm water to glacial bases and facilitate glacial motion. Lakes of a diameter greater than ~300 m are capable of creating a fluid-filled crevasse to the glacier/bed interface. When these crevasses form, the entirety of the lake's (relatively warm) contents can reach

9471-415: The ice sheet melts and becomes thinner, the weight of the overlying ice decreases. At a certain point, sea water could force itself into the gaps which form at the base of the ice sheet, and marine ice sheet instability (MISI) would occur. Even if the ice sheet is grounded below the sea level, MISI cannot occur as long as there is a stable ice shelf in front of it. The boundary between the ice sheet and

9594-440: The ice shelf, known as the grounding line , is particularly stable if it is constrained in an embayment . In that case, the ice sheet may not be thinning at all, as the amount of ice flowing over the grounding line would be likely to match the annual accumulation of ice from snow upstream. Otherwise, ocean warming at the base of an ice shelf tends to thin it through basal melting. As the ice shelf becomes thinner, it exerts less of

9717-466: The instability soon after it started. Some scientists - including the originators of the hypothesis, Robert DeConto and David Pollard - have suggested that the best way to resolve the question would be to precisely determine sea level rise during the Last Interglacial . MICI can be effectively ruled out if SLR at the time was lower than 4 m (13 ft), while it is very likely if

9840-416: The land rose, the crests ( eskers ) became the best sites for the first permanent settlements. It was easy to nourish oneself, thanks to the river, and these places were the easiest to defend. In addition, the river was easier to cross at this point. In addition, it is atop the esker of Enköpingsåsen that one finds most of the prehistoric sites, and many of today's routes follow the trace of ancient routes along

9963-520: The largest islands being Mattön, Torrön, Ängsön, Vedön, Rosön and Västerön. The park is situated in a continental climate (Dfb in the Köppen climate classification ), with rain mostly in summer. It is situated on the climate frontier between north and south, which helps determine the Limes Norrlandicus marking the border between the north of Scandinavia and the south. The snow cover lasts

10086-525: The list of species endangered in Sweden. The presence of dead wood favors the presence of numerous insects. Most of the forest insects live in the sapwood or between the sapwood and the bark . In particular, the Norway spruce and the English oak are the trees supporting the greatest richness in insects. The species of insect most associated with the park and the Lower Dalälven in general are mosquitos of

10209-521: The maximum speed is capped at 12 or 20 knots. The park and the surrounding zones attract many tourists. In addition, the Gysinge forge is visited annually by 250,000 people — a figure rapidly growing, the peninsula of Östa by 75,000 people and Tyttbo by 10,000 people. However, these visits are in general highly localized. The main entrances of the park are at Gysinge and Sevedskvarn, both situated near national route 56. These entries have parking . Camp grounds exist at Östa, Tyttbo and Österfärnebo, and it

10332-444: The middle Miocene , when the two passive continental margins which now form the uplands of West and East Greenland experienced uplift , and ultimately formed the upper planation surface at a height of 2000 to 3000 meter above sea level . Trosa Trosa is a locality and the seat of Trosa Municipality , Södermanland County , Sweden with 5,027 inhabitants in 2010 (town) and 11,417 in 2010 (municipality). The town

10455-406: The mine of Dannemora, to wood and to the energy of the Gysinge rapids. The forge grew rapidly and in the 18th century there were constructed around the forge homes, mills, stables, a manor and even a hotel. In the 18th century, the forge was one of the largest in the country, with 50 people working at the mill proper, and 3000 people connected to the forge in other ways. The forge was also the first in

10578-470: The nature of the soil. The poorer soils grow blueberries, bog bilberries , wild rosemary and cloudberry , whereas the richer soils are home in particular to Lily of the valley , woodland strawberries , purple small-reed and yellow loosestrife . Where the floods are less frequent the hardwoods themselves are absent, giving way to open country. The country is thus a prairie and, sometimes, this prairie finishes by transforming into bog. The vegetation of

10701-405: The north and the south, has favored the development of a fauna and flora of great biodiversity . The park possesses coniferous , mixed , and broadleaf forests, some of which quite ancient , spared by the logging industry because of their inaccessibility. These forests constitute the ideal environment for numerous species, in particular birds, with critical densities of woodpeckers and owls. If

10824-475: The northern hemisphere warmed considerably, dramatically increasing the release of methane from wetlands, that were otherwise tundra during glacial times. This methane quickly distributes evenly across the globe, becoming incorporated in Antarctic and Greenland ice. With this tie, paleoclimatologists have been able to say that the ice sheets on Greenland only began to warm after the Antarctic ice sheet had been warming for several thousand years. Why this pattern occurs

10947-399: The park are the peninsulas of Östa and Ista, since they are inhabited, but these are protected by nature reserves of 600 ha (1,500 acres) and 770 ha (1,900 acres), respectively. In addition, the park is bordered by several additional preserves: 920 ha (2,300 acres) at Hedesundafjärden, 950 ha (2,300 acres) at Jordbärsmuren-Ålbo, and 463 ha (1,140 acres) at Gysinge, for

11070-514: The park of environments and species characteristic to both the North and the South of Sweden. A great number of endangered species appear in the park: two species of vascular plants , 25 species of mosses , 34 species of lichens and 22 species of fungi. The park presents different environments as regards flora, the principal being the forests of conifers (1,000 ha (2,500 acres) making up 9.9% of

11193-399: The park), the mixed forests (1,460 ha (3,600 acres) making up 14.5% of the park), of open bogs (1,650 ha (4,100 acres) making up 16.3% of the park) and woods (500 ha (1,200 acres) making up 5% of the park) and finally wetlands (750 ha (1,900 acres) making up 7.4% of the park). The forests of conifers, principally of Norway spruce , are in particular present in the south of

11316-579: The park, around Tinäset, on the isle of Torrön and the peninsula of Öbyhalvön. These forests have not been logged since the 1950s and certain trees are themselves over 120 years old. These old trees as well as the presence of dead wood give this forest a very ancient appearance, and contribute to a great richness of lichens and fungi . The soil is often covered in moss, the characteristic species being Hylocomium splendens , but Anastrophyllum hellerianum and Nowellia curvifolia are also common. One can also find European blueberries and lingonberries in

11439-513: The park, with a maximum height of 18 m (59 ft), crisscrossing the region over 300 km (190 mi) between Trosa to the south and Bollnäs to the north. This ridge spans the river and creates, among other land features, the isle of Sandön and the peninsula of Ista. The river has largely flooded this flat and irregular zone, creating a mosaic of water, dry earth, and wetlands. The park also includes several bays (Östaviken, Andersboviken, Edsviken, etc.) as well as 200 islands and skerries,

11562-423: The park. More rarely, one sees also the wood lemming in the north part of the park. Four species of mammals present in the park are considered endangered in Sweden. Thus, the Eurasian lynx can be observed regularly around Öbyhalvön, Tinäset and Gärdsvekarna, alongside brown bears and gray wolves , although these are less frequent. The three other endangered species are the European otter that one can see near

11685-415: The peripheral ice stabilizing them is gone. Their collapse then exposes the ice masses following them to the same instability, potentially resulting in a self-sustaining cycle of cliff collapse and rapid ice sheet retreat - i.e. sea level rise of a meter or more by 2100 from Antarctica alone. This theory had been highly influential - in a 2020 survey of 106 experts, the paper which had advanced this theory

11808-414: The prairies is characterized by calamagrostides blanchâtres , by purple moor grass , bogbean , yellow loosestrife, swamp cinquefoil , lesser spearwort , common marsh-bedstraw , kingcup , purple loosestrife and violettes , the last being an endangered species in the country. In the bogs, vegetation is poor, with mainly bog myrtle , bog-rosemary , common cottongrass and species of Carex . The soil

11931-419: The presence of humans was relatively discreet since the Stone Age, concentrated principally atop the eskers, the development of mining activity (in particular of iron) has profoundly affected the region. The forests were exploited to feed the water-powered forges which grew up along the river. One of the most important was that of Gysinge, founded in 1668 and situated right next to the park. In 1975, in reaction to

12054-454: The protection of Färnebofjärden, in particular the area of Tinäset, and made many inventories in the area. At the beginning of the 1970s, Stora AB tried to clear all the forests it owned in the northern part of Tinäset. In response the ornithologist Stig Holmstedt made contact with the Swedish nature conservation society and formed a group to work towards the protection of the zone, which led to

12177-523: The rapids, and two species of bats , the pond bat , very rare in Sweden) and the common noctule . Birds are without question Färnebofjärden's most numerous class of animal. More than 200 species have been reported of which at least 107 nest regularly in the park. This richness is in part connected to the presence of characteristic species of both the south and the north. In addition, the park contains species of bird both aquatic and sylvan. The park has

12300-569: The remnants of the ice shelf did not accelerate. The collapse of the Larsen B shelf was preceded by thinning of just 1 metre per year, while some other Antarctic ice shelves have displayed thinning of tens of metres per year. Further, increased ocean temperatures of 1 °C may lead to up to 10 metres per year of basal melting. Ice shelves are always stable under mean annual temperatures of −9 °C, but never stable above −5 °C; this places regional warming of 1.5 °C, as preceded

12423-479: The river Nedre Dalälven. Like most of the Swedish national parks , the management and administration are divided between the Swedish environmental protection agency and the administrative council of the counties . Naturvårdsverket is charged with the proposal of new national parks, through consultation with administrative councils of the counties and municipalities; a vote of the Riksdag endorses their creation. If

12546-423: The river. Gysinge has a timber rafting museum. The wettest forests largely escaped the logging industry, thereby serving as sanctuaries of biodiversity during this period of exploitation. However, the most evident trace of the iron industry in the region is the forge of Gysinge. This forge was established in 1668 initially for the production of arms. The forge's location permitted a good access to metal, extracted at

12669-475: The sea had penetrated, which was the more restrictive definition which passed into French and English. The name Fjärnebo is the ancient name of the village of Österfärnebo ("East Färnebo"), situated near the park; its name changed in the 17th century to distinguish it from a Färnebo in Västmanland, which was itself rebaptized Västerfärnebo ("West Färnebo"). The name of the village means "habitation (bo) next to

12792-423: The sole fjärd with a mouth that remains unregulated. The regulation of the Österdalälven has all the same an impact upon Färnebofjärden, the great inundations of the plains during the spring floods being more rare, even if they are nevertheless capable of inundating several dozens of square kilometers. Besides the Dalälven, there are many streams inside the park, which flow into the river. Among these, one can number

12915-408: The species present, one can name several species of cyprinids (the family of carp , minnows , barbs , barbels , and others), of which in particular the asp , rare in Sweden. The waters abound also with northern pike , with specimens weighing sometimes 20 kg (44 lb), with European perch , with zander , and with grayling — which species is classified as endangered in Sweden, much like

13038-448: The surface of Greenland , or about 12% of the area of the Antarctic ice sheet . The term 'Greenland ice sheet' is often shortened to GIS or GrIS in scientific literature . Greenland has had major glaciers and ice caps for at least 18 million years, but a single ice sheet first covered most of the island some 2.6 million years ago. Since then, it has both grown and contracted significantly. The oldest known ice on Greenland

13161-474: The terrestrial ecoregion of Sarmatic mixed forests , not far from the frontier of the Scandinavian and Russian taiga . Almost all the types of forest of central Sweden are present in the park, which is due to both the presence of dry and wet environments and to the proximity of the Limes Norrlandicus line marking the frontier between the environments of the north and south. This implies the presence in

13284-470: The threat of the clearing of a vast forest, the movement for the creation of a national park began, culminating in the park's opening in 1998. The park was added to the Natura 2000 Network and included in the Ramsar Convention 's list of wetlands. The park and its environs are important tourist destinations. The river is its favored mode of discovery, but some hiking trails permit other explorations. The park

13407-513: The undergrowth. In the zones most subject to inundations, conifers are more rare, since they do not like in general the wetter zones. In these forests, one can find broadleaf trees such as the aspen , very common in the Lower Dalälven, but rare in the rest of the country. These forests also have English oaks and small-leaved lindens and the wetter forests are mostly made up of alders , birch trees and willows . The richness of these forests and in particular their undergrowth depends above all on

13530-587: The variations in shape of the Earth's orbit and its angle relative to the Sun, caused by the gravitational pull of other planets as they go through their own orbits. For instance, during at least the last 100,000 years, portions of the ice sheet covering much of North America, the Laurentide Ice Sheet broke apart sending large flotillas of icebergs into the North Atlantic. When these icebergs melted they dropped

13653-451: The whole section of the Lower Dalälven, the river did not have the time to flood a true valley. It thus had to adapt itself to the topology of the terrain, forming large fjärds with many isles in the flattest sections and by contrast a course narrower and faster at the different eskers encountered along the way. The park of Färnebofjärden is according to the classification of the WWF, situated in

13776-523: The world to use an oven for induction, the oven Kjellin. The forge closed at the beginning of the 20th century. A hydroelectric plant was constructed at Gysinge in 1917, but it consists only of one small scale plant, using one deflection of a small part of the river. The Lower Dalälven has for a long time been recognized in Sweden as a remarkable site worthy of protection. In the 1960s, the Swedish Society for Nature Conservation engaged itself for

13899-460: The year 2000, and was not conclusively detected until the 2020s. In the early 2000s, cooling over East Antarctica seemingly outweighing warming over the rest of the continent was frequently misinterpreted by the media and occasionally used as an argument for climate change denial . After 2009, improvements in Antarctica's instrumental temperature record have proven that the warming over West Antarctica resulted in consistent net warming across

14022-537: Was burnt down and plundered by Russians in 1719 during the Russian Pillage of 1719-1721 and was repeatedly attacked during the Great Northern War , but the local church and poor-house was spared at every occasion. Both these buildings are now on display in the center of Trosa and serves as a memory from those hard times. The economic base of the city was as earlier merchantmen and fishery. When

14145-886: Was considered more important than even the year 2014 IPCC Fifth Assessment Report . Sea level rise projections which involve MICI are much larger than the others, particularly under high warming rate. At the same time, this theory has also been highly controversial. It was originally proposed in order to describe how the large sea level rise during the Pliocene and the Last Interglacial could have occurred - yet more recent research found that these sea level rise episodes can be explained without any ice cliff instability taking place. Research in Pine Island Bay in West Antarctica (the location of Thwaites and Pine Island Glacier ) had found seabed gouging by ice from

14268-432: Was constructed in 1995 and offers a panoramic view over the major part of the park. Several hiking trails exist inside the park, in particular in the north part: on the isle of Mattön (between Gysinge and Sevedskvarn), a part of Gästrikeleden across the park from Gysinge, and from Kyrkstigen up to Skekarsbo. In the southern part, a long trail leads to Tinäset. Ice sheet In glaciology , an ice sheet , also known as

14391-400: Was covered with an ice sheet , which withdrew from the region about 10000 years ago. The glacier left behind in the region many eskers and moraines , such as the esker Enköpingsåsen. When the glacier withdrew, the soil had been so compressed by its mass that the entire zone situated to the east of Avesta found itself at sea level. During this maritime period, sediments deposited themselves on

14514-421: Was extracted from the marsh. The iron industry in the region necessitated a huge consumption of wood which initially justified silviculture in the park. Accordingly, the woods of Tinäset, for example, were heavily logged to feed the silver mine of Sala. At the end of the 19th century, many mills were constructed along the river: they were used for timber rafting. This activity ceased upon the creation of dams along

14637-497: Was known as a town in the 14th century. In the 15th century it was an important site for trade, and received its city privileges in 1454 by King Charles VIII of Sweden (a.k.a. Karl Knutsson Bonde ). Due to post-glacial rebound , the city center was moved in the early 17th century, to its present location by the estuary of the Trosa River. The city gained its valour at the new location from King Karl IX, 19 April 1610. The city

14760-466: Was stocked in nearby barns and carried to the surrounding villages during the winter to feed the animals. Some of these barns are still visible near Torrösundet and atop Västerön. Woodlands were summer granting lands ( transhumance ) and some cabins ( Fäbod ) were constructed there in order to look after the animals during this time. Fifteen of these cabins are scattered in and around the park, mainly near Tinäset and south of Gysinge. Transhumance ceased at

14883-527: Was the primary agent forcing Antarctic glaciation. The glaciation was favored by an interval when the Earth's orbit favored cool summers but oxygen isotope ratio cycle marker changes were too large to be explained by Antarctic ice-sheet growth alone indicating an ice age of some size. The opening of the Drake Passage may have played a role as well though models of the changes suggest declining CO 2 levels to have been more important. While there

15006-475: Was trapped in a narrow valley, becomes the Lower Dalälven ( Nedre Dalälven ), and large floodplains (called fjärdar ) alternate with zones of rapids. Färnebofjärden is the first big floodplain of the Lower Dalälven, situated between the rapids of Tyttbo to the west and Gysinge and Sevedskvarn to the east. At Gysinge, the river already has a watershed of 28,000 km (11,000 sq mi), for an average flow of 350 m/s (12,000 cu ft/s). While

15129-472: Was used to try to regulate these populations, which needed a waiver, its use being forbidden in Sweden and contrary to the principles of the national park. However, the project was not renewed, this method not being considered a durable solution and some scientists arguing that the mosquitos make up part of the region's ecosystem. 6000 years ago, the Lower Dalälven was a bay of the Littorina Sea, but as

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