133-498: Te Houhou / George Sound is a fiord of the South Island of New Zealand. It is one of the fiords that form the coast of Fiordland . The fiord is located between Taitetimu / Caswell Sound and Hāwea / Bligh Sound , on the northern central Fiordland coast. At 26 kilometres (16 mi) in length and over 1,500 metres (1,600 yd) wide at its widest point, it is the longest fiord in northern Fiordland. George Sound extends in
266-602: A Germanic noun for a travel : North Germanic ferd or färd and of the verb to travel , Dutch varen , German fahren ; English to fare . As a loanword from Norwegian, it is one of the few words in the English language to start with the sequence fj . The word was for a long time normally spelled f i ord , a spelling preserved in place names such as Grise Fiord . The fiord spelling mostly remains only in New Zealand English , as in
399-628: A common Germanic origin of the word. The landscape consists mainly of moraine heaps. The Föhrden and some "fjords" on the east side of Jutland, Denmark are also of glacial origin. But while the glaciers digging "real" fjords moved from the mountains to the sea, in Denmark and Germany they were tongues of a huge glacier covering the basin of which is now the Baltic Sea. See Förden and East Jutland Fjorde . Whereas fjord names mostly describe bays (though not always geological fjords), straits in
532-451: A consistent time period, assessments can attribute contributions to sea level rise and provide early indications of change in trajectory. This helps to inform adaptation plans. The different techniques used to measure changes in sea level do not measure exactly the same level. Tide gauges can only measure relative sea level. Satellites can also measure absolute sea level changes. To get precise measurements for sea level, researchers studying
665-451: A fjord as a kind of sea ( Māori : tai ) that runs by a bluff ( matapari , altogether tai matapari "bluff sea"). The term "fjord" is sometimes applied to steep-sided inlets which were not created by glaciers. Most such inlets are drowned river canyons or rias . Examples include: Some Norwegian freshwater lakes that have formed in long glacially carved valleys with sill thresholds, ice front deltas or terminal moraines blocking
798-456: A glacial river flows in. Velfjorden has little inflow of freshwater. In 2000, some coral reefs were discovered along the bottoms of the Norwegian fjords. These reefs were found in fjords from the north of Norway to the south. The marine life on the reefs is believed to be one of the most important reasons why the Norwegian coastline is such a generous fishing ground. Since this discovery
931-421: A highly productive group of phytoplankton that enable such fjords to be valuable feeding grounds for other species. It is possible that as climate change reduces long-term meltwater output, nutrient dynamics within such fjords will shift to favor less productive species, destabilizing the food web ecology of fjord systems. In addition to nutrient flux, sediment carried by flowing glaciers can become suspended in
1064-487: A larger role over such timescales. Ice loss from Antarctica is likely to dominate very long-term SLR, especially if the warming exceeds 2 °C (3.6 °F). Continued carbon dioxide emissions from fossil fuel sources could cause additional tens of metres of sea level rise, over the next millennia. Burning of all fossil fuels on Earth is sufficient to melt the entire Antarctic ice sheet, causing about 58 m (190 ft) of sea level rise. Year 2021 IPCC estimates for
1197-529: A long, narrow inlet. In eastern Norway, the term is also applied to long narrow freshwater lakes ( Randsfjorden and Tyrifjorden ) and sometimes even to rivers (for instance in Flå Municipality in Hallingdal , the Hallingdal river is referred to as fjorden ). In southeast Sweden, the name fjard fjärd is a subdivision of the term 'fjord' used for bays, bights and narrow inlets on
1330-701: A much longer period. Coverage of tide gauges started mainly in the Northern Hemisphere . Data for the Southern Hemisphere remained scarce up to the 1970s. The longest running sea-level measurements, NAP or Amsterdam Ordnance Datum were established in 1675, in Amsterdam . Record collection is also extensive in Australia . They include measurements by Thomas Lempriere , an amateur meteorologist, beginning in 1837. Lempriere established
1463-544: A narrower sound is called sund . In the Finnish language , a word vuono is used although there is only one fjord in Finland. In old Norse genitive was fjarðar whereas dative was firði . The dative form has become common place names like Førde (for instance Førde ), Fyrde or Førre (for instance Førre ). The German use of the word Föhrde for long narrow bays on their Baltic Sea coastline, indicates
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#17327660831281596-508: A period of thousands of years. The size of the rise in sea level implies a large contribution from the Antarctic and Greenland ice sheets. Levels of atmospheric carbon dioxide of around 400 parts per million (similar to 2000s) had increased temperature by over 2–3 °C (3.6–5.4 °F) around three million years ago. This temperature increase eventually melted one third of Antarctica's ice sheet, causing sea levels to rise 20 meters above
1729-500: A protected passage almost the entire 1,601 km (995 mi) route from Stavanger to North Cape , Norway. The Blindleia is a skerry-protected waterway that starts near Kristiansand in southern Norway and continues past Lillesand . The Swedish coast along Bohuslän is likewise skerry guarded. The Inside Passage provides a similar route from Seattle , Washington , and Vancouver , British Columbia , to Skagway , Alaska . Yet another such skerry-protected passage extends from
1862-576: A range of 28–61 cm (11–24 in). The "moderate" scenario, where CO 2 emissions take a decade or two to peak and its atmospheric concentration does not plateau until the 2070s is called RCP 4.5. Its likely range of sea level rise is 36–71 cm (14–28 in). The highest scenario in RCP8.5 pathway sea level would rise between 52 and 98 cm ( 20 + 1 ⁄ 2 and 38 + 1 ⁄ 2 in). AR6 had equivalents for both scenarios, but it estimated larger sea level rise under both. In AR6,
1995-481: A range with a lower and upper limit to reflect the unknowns. The scenarios in the 2013–2014 Fifth Assessment Report (AR5) were called Representative Concentration Pathways , or RCPs and the scenarios in the IPCC Sixth Assessment Report (AR6) are known as Shared Socioeconomic Pathways , or SSPs. A large difference between the two was the addition of SSP1-1.9 to AR6, which represents meeting
2128-584: A roughly northwestern direction, and has two major indentations; Southwest Arm in the south, and Anchorage Cove halfway along its northeastern shore. Several rivers enter the fiord, the largest of which are the George River , the Whitewater River , and the Edith River . The George River flows into Anchorage Cove, halfway along the northeast coast of the fiord. The Whitewater River enters
2261-665: A sea-level benchmark on a small cliff on the Isle of the Dead near the Port Arthur convict settlement in 1841. Together with satellite data for the period after 1992, this network established that global mean sea level rose 19.5 cm (7.7 in) between 1870 and 2004 at an average rate of about 1.44 mm/yr. (For the 20th century the average is 1.7 mm/yr.) By 2018, data collected by Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO) had shown that
2394-470: A sharp reduction in greenhouse gas emissions, this may increase to hundreds of millions in the latter decades of the century. Local factors like tidal range or land subsidence will greatly affect the severity of impacts. For instance, sea level rise in the United States is likely to be two to three times greater than the global average by the end of the century. Yet, of the 20 countries with
2527-675: A suffix in names of some Scandinavian fjords and has in same cases also been transferred to adjacent settlements or surrounding areas for instance Hardanger , Stavanger , and Geiranger . The differences in usage between the English and the Scandinavian languages have contributed to confusion in the use of the term fjord. Bodies of water that are clearly fjords in Scandinavian languages are not considered fjords in English; similarly bodies of water that would clearly not be fjords in
2660-541: A threshold around 100 to 200 m (330 to 660 ft) deep. Hardangerfjord is made up of several basins separated by thresholds: The deepest basin Samlafjorden between Jonaneset ( Jondal ) and Ålvik with a distinct threshold at Vikingneset in Kvam Municipality . Hanging valleys are common along glaciated fjords and U-shaped valleys . A hanging valley is a tributary valley that is higher than
2793-593: A version of SSP5-8.5 where these processes take place, and in that case, sea level rise of up to 1.6 m ( 5 + 1 ⁄ 3 ft) by 2100 could not be ruled out. The greatest uncertainty with sea level rise projections is associated with the so-called marine ice sheet instability (MISI), and, even more so, Marine Ice Cliff Instability (MICI). These processes are mainly associated with West Antarctic Ice Sheet, but may also apply to some of Greenland's glaciers. The former suggests that when glaciers are mostly underwater on retrograde (backwards-sloping) bedrock,
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#17327660831282926-582: Is 2,000 m (6,562 ft) below the surrounding regional topography. Fjord lakes are common on the inland lea of the Coast Mountains and Cascade Range ; notable ones include Lake Chelan , Seton Lake , Chilko Lake , and Atlin Lake . Kootenay Lake , Slocan Lake and others in the basin of the Columbia River are also fjord-like in nature, and created by glaciation in the same way. Along
3059-402: Is a stub . You can help Misplaced Pages by expanding it . This article about a fjord is a stub . You can help Misplaced Pages by expanding it . Fiord In physical geography , a fjord (also spelled fiord in New Zealand English ; ( / ˈ f j ɔːr d , f iː ˈ ɔːr d / ) is a long, narrow sea inlet with steep sides or cliffs, created by a glacier . Fjords exist on
3192-412: Is also often described as a fjord, but is actually a freshwater lake cut off from the sea, so is not a fjord in the English sense of the term. Locally they refer to it as a "landlocked fjord". Such lakes are sometimes called "fjord lakes". Okanagan Lake was the first North American lake to be so described, in 1962. The bedrock there has been eroded up to 650 m (2,133 ft) below sea level, which
3325-430: Is at least 500 m (1,600 ft) deep and water takes an average of 16 years to flow through the lake. Such lakes created by glacial action are also called fjord lakes or moraine-dammed lakes . Some of these lakes were salt after the ice age but later cut off from the ocean during the post-glacial rebound . At the end of the ice age Eastern Norway was about 200 m (660 ft) lower (the marine limit). When
3458-456: Is borrowed from Norwegian , where it is pronounced [ˈfjuːr] , [ˈfjøːr] , [ˈfjuːɽ] or [ˈfjøːɽ] in various dialects and has a more general meaning, referring in many cases to any long, narrow body of water, inlet or channel (for example, see Oslofjord ). The Norwegian word is inherited from Old Norse fjǫrðr , a noun which refers to a 'lake-like' body of water used for passage and ferrying and
3591-402: Is by lowering the global temperature to 1 °C (1.8 °F) below the preindustrial level. This would be 2 °C (3.6 °F) below the temperature of 2020. Other researchers suggested that a climate engineering intervention to stabilize the ice sheet's glaciers may delay its loss by centuries and give more time to adapt. However this is an uncertain proposal, and would end up as one of
3724-620: Is closely related to the noun ferð "travelling, ferrying, journey". Both words go back to Indo-European *pértus "crossing", from the root *per- "cross". The words fare and ferry are of the same origin. The Scandinavian fjord , Proto-Scandinavian * ferþuz , is the origin for similar Germanic words: Icelandic fjörður , Faroese fjørður , Swedish fjärd (for Baltic waterbodies), Scots firth (for marine waterbodies, mainly in Scotland and northern England). The Norse noun fjǫrðr
3857-454: Is due to the high level of inertia in the carbon cycle and the climate system, owing to factors such as the slow diffusion of heat into the deep ocean , leading to a longer climate response time. A 2018 paper estimated that sea level rise in 2300 would increase by a median of 20 cm (8 in) for every five years CO 2 emissions increase before peaking. It shows a 5% likelihood of a 1 m ( 3 + 1 ⁄ 2 ft) increase due to
3990-653: Is fairly new, little research has been done. The reefs are host to thousands of lifeforms such as plankton , coral , anemones , fish, several species of shark, and many more. Most are specially adapted to life under the greater pressure of the water column above it, and the total darkness of the deep sea. New Zealand's fjords are also host to deep-water corals , but a surface layer of dark fresh water allows these corals to grow in much shallower water than usual. An underwater observatory in Milford Sound allows tourists to view them without diving. In some places near
4123-505: Is located on the southern shore of Lake Superior in Michigan . The principal mountainous regions where fjords have formed are in the higher middle latitudes and the high latitudes reaching to 80°N (Svalbard, Greenland), where, during the glacial period, many valley glaciers descended to the then-lower sea level. The fjords develop best in mountain ranges against which the prevailing westerly marine winds are orographically lifted over
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4256-465: Is now unstoppable. However the temperature changes in future, the warming of 2000–2019 had already damaged the ice sheet enough for it to eventually lose ~3.3% of its volume. This is leading to 27 cm ( 10 + 1 ⁄ 2 in) of future sea level rise. At a certain level of global warming, the Greenland ice sheet will almost completely melt. Ice cores show this happened at least once over
4389-505: Is often described as the world's strongest tidal current . These characteristics distinguish fjords from rias (such as the Bay of Kotor ), which are drowned valleys flooded by the rising sea. Drammensfjorden is cut almost in two by the Svelvik "ridge", a sandy moraine that was below sea level when it was covered by ice, but after the post-glacial rebound reaches 60 m (200 ft) above
4522-572: Is removed (also called isostasy or glacial rebound). In some cases, this rebound is faster than sea level rise . Most fjords are deeper than the adjacent sea ; Sognefjord , Norway , reaches as much as 1,300 m (4,265 ft) below sea level . Fjords generally have a sill or shoal (bedrock) at their mouth caused by the previous glacier's reduced erosion rate and terminal moraine . In many cases this sill causes extreme currents and large saltwater rapids (see skookumchuck ). Saltstraumen in Norway
4655-520: Is the East Antarctic Ice Sheet (EAIS). It is 2.2 km thick on average and holds enough ice to raise global sea levels by 53.3 m (174 ft 10 in) Its great thickness and high elevation make it more stable than the other ice sheets. As of the early 2020s, most studies show that it is still gaining mass. Some analyses have suggested it began to lose mass in the 2000s. However they over-extrapolated some observed losses on to
4788-409: Is the fastest it had been over at least the past 3,000 years. While sea level rise is uniform around the globe, some land masses are moving up or down as a consequence of subsidence (land sinking or settling) or post-glacial rebound (land rising as melting ice reduces weight). Therefore, local relative sea level rise may be higher or lower than the global average. Changing ice masses also affect
4921-470: Is the freshwater fjord Movatnet (Mo lake) that until 1743 was separated from Romarheimsfjorden by an isthmus and connected by a short river. During a flood in November 1743, the river bed eroded and sea water could flow into the lake at high tide. Eventually, Movatnet became a saltwater fjord and renamed Mofjorden ( Mofjorden ). Like fjords, freshwater lakes are often deep. For instance Hornindalsvatnet
5054-409: Is the isthmus with a village between Hornindalsvatnet lake and Nordfjord . Such lakes are also denoted fjord valley lakes by geologists. One of Norway's largest is Tyrifjorden at 63 m (207 ft) above sea level and an average depth at 97 m (318 ft) most of the lake is under sea level. Norway's largest lake, Mjøsa , is also referred to as "the fjord" by locals. Another example
5187-462: Is the largest and most influential scientific organization on climate change, and since 1990, it provides several plausible scenarios of 21st century sea level rise in each of its major reports. The differences between scenarios are mainly due to uncertainty about future greenhouse gas emissions. These depend on future economic developments, and also future political action which is hard to predict. Each scenario provides an estimate for sea level rise as
5320-727: Is the main cause. Between 1993 and 2018, melting ice sheets and glaciers accounted for 44% of sea level rise , with another 42% resulting from thermal expansion of water . Sea level rise lags behind changes in the Earth 's temperature by many decades, and sea level rise will therefore continue to accelerate between now and 2050 in response to warming that has already happened. What happens after that depends on human greenhouse gas emissions . If there are very deep cuts in emissions, sea level rise would slow between 2050 and 2100. It could then reach by 2100 slightly over 30 cm (1 ft) from now and approximately 60 cm (2 ft) from
5453-410: Is usually a large inflow of river water in the inner areas. This freshwater gets mixed with saltwater creating a layer of brackish water with a slightly higher surface than the ocean which in turn sets up a current from the river mouths towards the ocean. This current is gradually more salty towards the coast and right under the surface current there is a reverse current of saltier water from the coast. In
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5586-529: The Amundsen Sea Embayment played a disproportionate role. The median estimated increase in sea level rise from Antarctica by 2100 is ~11 cm (5 in). There is no difference between scenarios, because the increased warming would intensify the water cycle and increase snowfall accumulation over the EAIS at about the same rate as it would increase ice loss from WAIS. However, most of
5719-636: The British Columbia Coast , a notable fjord-lake is Owikeno Lake , which is a freshwater extension of Rivers Inlet . Quesnel Lake , located in central British Columbia, is claimed to be the deepest fjord formed lake on Earth. A family of freshwater fjords are the embayments of the North American Great Lakes. Baie Fine is located on the northwestern coast of Georgian Bay of Lake Huron in Ontario , and Huron Bay
5852-603: The Henry Pass . A. W. Reed lists two plausible origins for the fiord's name in his seminal Place Names of New Zealand (1975): "Although it has been recorded that the sound was named after the King George , commanded by Captain S. Chase, it is almost certain that it was named after George Stevens, the pilot of HMS Acheron ." In October 2019, the name of the fiord was officially altered to Te Houhou / George Sound. This Fiordland , New Zealand geography article
5985-599: The Pacific Decadal Oscillation (PDO) and the El Niño–Southern Oscillation (ENSO) change from one state to the other. The PDO is a basin-wide climate pattern consisting of two phases, each commonly lasting 10 to 30 years. The ENSO has a shorter period of 2 to 7 years. The global network of tide gauges is the other important source of sea-level observations. Compared to the satellite record, this record has major spatial gaps but covers
6118-605: The SROCC assessed several studies attempting to estimate 2300 sea level rise caused by ice loss in Antarctica alone, arriving at projected estimates of 0.07–0.37 metres (0.23–1.21 ft) for the low emission RCP2.6 scenario, and 0.60–2.89 metres (2.0–9.5 ft) in the high emission RCP8.5 scenario. This wide range of estimates is mainly due to the uncertainties regarding marine ice sheet and marine ice cliff instabilities. The world's largest potential source of sea level rise
6251-459: The Scandinavian sense of the term, are not universally considered to be fjords by the scientific community, because although glacially formed, most Finnmark fjords lack the steep-sided valleys of the more southerly Norwegian fjords. The glacial pack was deep enough to cover even the high grounds when they were formed. The Oslofjord , on the other hand, is a rift valley , and not glacially formed. The indigenous Māori people of New Zealand see
6384-613: The Straits of Magellan north for 800 km (500 mi). Fjords provide unique environmental conditions for phytoplankton communities. In polar fjords, glacier and ice sheet outflow add cold, fresh meltwater along with transported sediment into the body of water. Nutrients provided by this outflow can significantly enhance phytoplankton growth. For example, in some fjords of the West Antarctic Peninsula (WAP), nutrient enrichment from meltwater drives diatom blooms,
6517-543: The Viking settlers—though the inlet at that place in modern terms is an estuary , not a fjord. Similarly the name of Milford (now Milford Haven) in Wales is derived from Melrfjǫrðr ("sandbank fjord/inlet"), though the inlet on which it is located is actually a ria. Before or in the early phase of Old Norse angr was another common noun for fjords and other inlets of the ocean. This word has survived only as
6650-637: The bedrock underlying the WAIS lies well below sea level, and it has to be buttressed by the Thwaites and Pine Island glaciers. If these glaciers were to collapse, the entire ice sheet would as well. Their disappearance would take at least several centuries, but is considered almost inevitable, as their bedrock topography deepens inland and becomes more vulnerable to meltwater, in what is known as marine ice sheet instability. The contribution of these glaciers to global sea levels has already accelerated since
6783-430: The ice shelves propping them up are gone. The 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. This theory had been highly influential - in a 2020 survey of 106 experts, the 2016 paper which suggested 1 m ( 3 + 1 ⁄ 2 ft) or more of sea level rise by 2100 from Antarctica alone,
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#17327660831286916-973: The 19th century. With high emissions it would instead accelerate further, and could rise by 1.0 m ( 3 + 1 ⁄ 3 ft) or even 1.6 m ( 5 + 1 ⁄ 3 ft) by 2100. In the long run, sea level rise would amount to 2–3 m (7–10 ft) over the next 2000 years if warming stays to its current 1.5 °C (2.7 °F) over the pre-industrial past. It would be 19–22 metres (62–72 ft) if warming peaks at 5 °C (9.0 °F). Rising seas affect every coastal and island population on Earth. This can be through flooding, higher storm surges , king tides , and tsunamis . There are many knock-on effects. They lead to loss of coastal ecosystems like mangroves . Crop yields may reduce because of increasing salt levels in irrigation water. Damage to ports disrupts sea trade. The sea level rise projected by 2050 will expose places currently inhabited by tens of millions of people to annual flooding. Without
7049-584: The Antarctic continent stores around 60% of the world's fresh water. Excluding groundwater this is 90%. Antarctica is experiencing ice loss from coastal glaciers in the West Antarctica and some glaciers of East Antarctica . However it is gaining mass from the increased snow build-up inland, particularly in the East. This leads to contradicting trends. There are different satellite methods for measuring ice mass and change. Combining them helps to reconcile
7182-503: The Earth was 2 °C (3.6 °F) warmer than pre-industrial temperatures was 120,000 years ago. This was when warming due to Milankovitch cycles (changes in the amount of sunlight due to slow changes in the Earth's orbit) caused the Eemian interglacial . Sea levels during that warmer interglacial were at least 5 m (16 ft) higher than now. The Eemian warming was sustained over
7315-438: The Greenland ice sheet between 1992 and 2018 amounted to 3,902 gigatons (Gt) of ice. This is equivalent to a SLR contribution of 10.8 mm. The contribution for the 2012–2016 period was equivalent to 37% of sea level rise from land ice sources (excluding thermal expansion). This observed rate of ice sheet melting is at the higher end of predictions from past IPCC assessment reports. In 2021, AR6 estimated that by 2100,
7448-604: 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. Even if the temperature stabilizes, significant sea-level rise (SLR) will continue for centuries, consistent with paleo records of sea level rise. This
7581-803: The Limfjord once was a fjord until the sea broke through from the west. Ringkøbing Fjord on the western coast of Jutland is a lagoon . The long narrow fjords of Denmark's Baltic Sea coast like the German Förden were dug by ice moving from the sea upon land, while fjords in the geological sense were dug by ice moving from the mountains down to the sea. However, some definitions of a fjord is: "A long narrow inlet consisting of only one inlet created by glacial activity". Examples of Danish fjords are: Kolding Fjord , Vejle Fjord and Mariager Fjord . The fjords in Finnmark in Norway, which are fjords in
7714-605: The SSP1-1.9 scenario would result in sea level rise in the 17–83% range of 37–86 cm ( 14 + 1 ⁄ 2 –34 in). In the SSP1-2.6 pathway the range would be 46–99 cm (18–39 in), for SSP2-4.5 a 66–133 cm (26– 52 + 1 ⁄ 2 in) range by 2100 and for SSP5-8.5 a rise of 98–188 cm ( 38 + 1 ⁄ 2 –74 in). It stated that the "low-confidence, high impact" projected 0.63–1.60 m (2–5 ft) mean sea level rise by 2100, and that by 2150,
7847-522: The SSP1-2.6 pathway results in a range of 32–62 cm ( 12 + 1 ⁄ 2 – 24 + 1 ⁄ 2 in) by 2100. The "moderate" SSP2-4.5 results in a 44–76 cm ( 17 + 1 ⁄ 2 –30 in) range by 2100 and SSP5-8.5 led to 65–101 cm ( 25 + 1 ⁄ 2 –40 in). This general increase of projections in AR6 came after the improvements in ice-sheet modeling and the incorporation of structured expert judgements. These decisions came as
7980-546: The Scandinavian sense have been named or suggested to be fjords. Examples of this confused usage follow. In the Danish language some inlets are called a fjord, but are, according to the English language definition, technically not a fjord, such as Roskilde Fjord . Limfjord in English terminology is a sound , since it separates the North Jutlandic Island (Vendsyssel-Thy) from the rest of Jutland . However,
8113-476: The Swedish Baltic Sea coast, and in most Swedish lakes. This latter term is also used for bodies of water off the coast of Finland where Finland Swedish is spoken. In Danish, the word may even apply to shallow lagoons . In modern Icelandic, fjörður is still used with the broader meaning of firth or inlet. In Faroese fjørður is used both about inlets and about broader sounds, whereas
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#17327660831288246-561: The WAIS to contribute up to 41 cm (16 in) by 2100 under the low-emission scenario and up to 57 cm (22 in) under the highest-emission one. Ice cliff instability would cause a contribution of 1 m ( 3 + 1 ⁄ 2 ft) or more if it were applicable. The melting of all the ice in West Antarctica would increase the total sea level rise to 4.3 m (14 ft 1 in). However, mountain ice caps not in contact with water are less vulnerable than
8379-444: The amount of sea level rise over the next 2,000 years project that: Sea levels would continue to rise for several thousand years after the ceasing of emissions, due to the slow nature of climate response to heat. The same estimates on a timescale of 10,000 years project that: Variations in the amount of water in the oceans, changes in its volume, or varying land elevation compared to the sea surface can drive sea level changes. Over
8512-422: The average world ocean temperature by 0.01 °C (0.018 °F) would increase atmospheric temperature by approximately 10 °C (18 °F). So a small change in the mean temperature of the ocean represents a very large change in the total heat content of the climate system. Winds and currents move heat into deeper parts of the ocean. Some of it reaches depths of more than 2,000 m (6,600 ft). When
8645-459: The best Paris climate agreement goal of 1.5 °C (2.7 °F). In that case, the likely range of sea level rise by 2100 is 28–55 cm (11– 21 + 1 ⁄ 2 in). The lowest scenario in AR5, RCP2.6, would see greenhouse gas emissions low enough to meet the goal of limiting warming by 2100 to 2 °C (3.6 °F). It shows sea level rise in 2100 of about 44 cm (17 in) with
8778-485: The best-case scenario, ice sheet under SSP1-2.6 gains enough mass by 2100 through surface mass balance feedbacks to reduce the sea levels by 2 cm (1 in). In the worst case, it adds 15 cm (6 in). For SSP5-8.5, the best-case scenario is adding 5 cm (2 in) to sea levels, and the worst-case is adding 23 cm (9 in). Greenland's peripheral glaciers and ice caps crossed an irreversible tipping point around 1997. Sea level rise from their loss
8911-485: The coasts of Antarctica , the Arctic , and surrounding landmasses of the northern and southern hemispheres. Norway's coastline is estimated to be 29,000 km (18,000 mi) long with its nearly 1,200 fjords, but only 2,500 km (1,600 mi) long excluding the fjords . A true fjord is formed when a glacier cuts a U-shaped valley by ice segregation and abrasion of the surrounding bedrock. According to
9044-459: The contribution from these is thought to be small. Glacier retreat and ocean expansion have dominated sea level rise since the start of the 20th century. Some of the losses from glaciers are offset when precipitation falls as snow, accumulates and over time forms glacial ice. If precipitation, surface processes and ice loss at the edge balance each other, sea level remains the same. Because of this precipitation began as water vapor evaporated from
9177-434: The deeper parts of the fjord the cold water remaining from winter is still and separated from the atmosphere by the brackish top layer. This deep water is ventilated by mixing with the upper layer causing it to warm and freshen over the summer. In fjords with a shallow threshold or low levels of mixing this deep water is not replaced every year and low oxygen concentration makes the deep water unsuitable for fish and animals. In
9310-407: The deepest fjord basins. Near the very coast, the typical West Norwegian glacier spread out (presumably through sounds and low valleys) and lost their concentration and reduced the glaciers' power to erode leaving bedrock thresholds. Bolstadfjorden is 160 m (520 ft) deep with a threshold of only 1.5 m (4 ft 11 in), while the 1,300 m (4,300 ft) deep Sognefjorden has
9443-517: The differences. However, there can still be variations between the studies. In 2018, a systematic review estimated average annual ice loss of 43 billion tons (Gt) across the entire continent between 1992 and 2002. This tripled to an annual average of 220 Gt from 2012 to 2017. However, a 2021 analysis of data from four different research satellite systems ( Envisat , European Remote-Sensing Satellite , GRACE and GRACE-FO and ICESat ) indicated annual mass loss of only about 12 Gt from 2012 to 2016. This
9576-593: The direction of Sognefjord and the fold pattern. This relationship between fractures and direction of fjords is also observed in Lyngen . Preglacial, tertiary rivers presumably eroded the surface and created valleys that later guided the glacial flow and erosion of the bedrock. This may in particular have been the case in Western Norway where the tertiary uplift of the landmass amplified eroding forces of rivers. Confluence of tributary fjords led to excavation of
9709-456: The distribution of sea water around the globe through gravity. Several approaches are used for sea level rise (SLR) projections. One is process-based modeling, where ice melting is computed through an ice-sheet model and rising sea temperature and expansion through a general circulation model , and then these contributions are added up. The so-called semi-empirical approach instead applies statistical techniques and basic physical modeling to
9842-428: The empirical 2.5 °C (4.5 °F) upper limit from ice cores. If temperatures reach or exceed that level, reducing the global temperature to 1.5 °C (2.7 °F) above pre-industrial levels or lower would prevent the loss of the entire ice sheet. One way to do this in theory would be large-scale carbon dioxide removal , but there would still be cause of greater ice losses and sea level rise from Greenland than if
9975-403: The extremely low probability of large climate change-induced increases in precipitation greatly elevating ice sheet surface mass balance .) In 2020, 106 experts who contributed to 6 or more papers on sea level estimated median 118 cm ( 46 + 1 ⁄ 2 in) SLR in the year 2300 for the low-warming RCP2.6 scenario and the median of 329 cm ( 129 + 1 ⁄ 2 in) for
10108-474: The fiord's southwest coast almost opposite the mouth of the cove. The Edith River and nearby smaller Katherine Creek both enter the southeastern end of the fiord, with the Edith River flowing through Lake Alice and over the 56-metre (184 ft) Alice Falls into the waters of the fiord. A walking track connects the mouth of Katherine Creek with Lake Hankinson , close to the top of Lake Te Anau , over
10241-419: The fjord. In the 19th century, Jens Esmark introduced the theory that fjords are or have been created by glaciers and that large parts of Northern Europe had been covered by thick ice in prehistory. Thresholds at the mouths and overdeepening of fjords compared to the ocean are the strongest evidence of glacial origin, and these thresholds are mostly rocky. Thresholds are related to sounds and low land where
10374-413: The fjord. Bolstadfjorden has a threshold of only 1.5 m (4 ft 11 in) and strong inflow of freshwater from Vosso river creates a brackish surface that blocks circulation of the deep fjord. The deeper, salt layers of Bolstadfjorden are deprived of oxygen and the seabed is covered with organic material. The shallow threshold also creates a strong tidal current. During the summer season, there
10507-489: The formation of sea ice. The study of phytoplankton communities within fjords is an active area of research, supported by groups such as FjordPhyto, a citizen science initiative to study phytoplankton samples collected by local residents, tourists, and boaters of all backgrounds. An epishelf lake forms when meltwater is trapped behind a floating ice shelf and the freshwater floats on the denser saltwater below. Its surface may freeze forming an isolated ecosystem. The word fjord
10640-559: The global mean sea level was rising by 3.2 mm ( 1 ⁄ 8 in) per year. This was double the average 20th century rate. The 2023 World Meteorological Organization report found further acceleration to 4.62 mm/yr over the 2013–2022 period. These observations help to check and verify predictions from climate change simulations. Regional differences are also visible in the tide gauge data. Some are caused by local sea level differences. Others are due to vertical land movements. In Europe , only some land areas are rising while
10773-1034: The greatest exposure to sea level rise, twelve are in Asia , including Indonesia , Bangladesh and the Philippines. The resilience and adaptive capacity of ecosystems and countries also varies, which will result in more or less pronounced impacts. The greatest impact on human populations in the near term will occur in the low-lying Caribbean and Pacific islands . Sea level rise will make many of them uninhabitable later this century. Societies can adapt to sea level rise in multiple ways. Managed retreat , accommodating coastal change , or protecting against sea level rise through hard-construction practices like seawalls are hard approaches. There are also soft approaches such as dune rehabilitation and beach nourishment . Sometimes these adaptation strategies go hand in hand. At other times choices must be made among different strategies. Poorer nations may also struggle to implement
10906-536: The high-warming RCP8.5. The former scenario had the 5%–95% confidence range of 24–311 cm ( 9 + 1 ⁄ 2 – 122 + 1 ⁄ 2 in), and the latter of 88–783 cm ( 34 + 1 ⁄ 2 – 308 + 1 ⁄ 2 in). After 500 years, sea level rise from thermal expansion alone may have reached only half of its eventual level - likely within ranges of 0.5–2 m ( 1 + 1 ⁄ 2 – 6 + 1 ⁄ 2 ft). Additionally, tipping points of Greenland and Antarctica ice sheets are likely to play
11039-417: The hypothesis after 2016 often suggested that the ice shelves in the real world may collapse too slowly to make this scenario relevant, or that ice mélange - debris produced as the glacier breaks down - would quickly build up in front of the glacier and significantly slow or even outright stop the instability soon after it began. Due to these uncertainties, some scientists - including the originators of
11172-543: 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 the SLR was greater than 6 m ( 19 + 1 ⁄ 2 ft). As of 2023, the most recent analysis indicates that
11305-415: The ice and oceans factor in ongoing deformations of the solid Earth . They look in particular at landmasses still rising from past ice masses retreating , and the Earth's gravity and rotation . Since the launch of TOPEX/Poseidon in 1992, an overlapping series of altimetric satellites has been continuously recording the sea level and its changes. These satellites can measure the hills and valleys in
11438-477: The ice cap receded and allowed the ocean to fill valleys and lowlands, and lakes like Mjøsa and Tyrifjorden were part of the ocean while Drammen valley was a narrow fjord. At the time of the Vikings Drammensfjord was still four or five m (13 or 16 ft) higher than today and reached the town of Hokksund , while parts of what is now the city of Drammen was under water. After the ice age
11571-464: The ice could spread out and therefore have less erosive force. John Walter Gregory argued that fjords are of tectonic origin and that glaciers had a negligible role in their formation. Gregory's views were rejected by subsequent research and publications. In the case of Hardangerfjord the fractures of the Caledonian fold has guided the erosion by glaciers, while there is no clear relation between
11704-408: The ice on Earth would result in about 70 m (229 ft 8 in) of sea level rise, although this would require at least 10,000 years and up to 10 °C (18 °F) of global warming. The oceans store more than 90% of the extra heat added to the climate system by Earth's energy imbalance and act as a buffer against its effects. This means that the same amount of heat that would increase
11837-735: The largest potential source of sea level rise. However the West Antarctic ice sheet (WAIS) is substantially more vulnerable. Temperatures on West Antarctica have increased significantly, unlike East Antarctica and the Antarctic Peninsula . The trend is between 0.08 °C (0.14 °F) and 0.96 °C (1.73 °F) per decade between 1976 and 2012. Satellite observations recorded a substantial increase in WAIS melting from 1992 to 2017. This resulted in 7.6 ± 3.9 mm ( 19 ⁄ 64 ± 5 ⁄ 32 in) of Antarctica sea level rise. Outflow glaciers in
11970-414: The last million years, during which the temperatures have at most been 2.5 °C (4.5 °F) warmer than the preindustrial average. 2012 modelling suggested that the tipping point of the ice sheet was between 0.8 °C (1.4 °F) and 3.2 °C (5.8 °F). 2023 modelling has narrowed the tipping threshold to a 1.7 °C (3.1 °F)-2.3 °C (4.1 °F) range, which is consistent with
12103-446: The level of the original sea level. In Eidfjord, Eio has dug through the original delta and left a 110 m (360 ft) terrace while lake is only 19 m (62 ft) above sea level. Such deposits are valuable sources of high-quality building materials (sand and gravel) for houses and infrastructure. Eidfjord village sits on the eid or isthmus between Eidfjordvatnet lake and Eidfjorden branch of Hardangerfjord. Nordfjordeid
12236-471: The main fjord. The mouth of Fjærlandsfjord is about 400 m (1,300 ft) deep while the main fjord is 1,200 m (3,900 ft) nearby. The mouth of Ikjefjord is only 50 m (160 ft) deep while the main fjord is around 1,300 m (4,300 ft) at the same point. During the winter season, there is usually little inflow of freshwater. Surface water and deeper water (down to 100 m or 330 ft or more) are mixed during winter because of
12369-439: The main valley and was created by tributary glacier flows into a glacier of larger volume. The shallower valley appears to be 'hanging' above the main valley or a fjord. Often, waterfalls form at or near the outlet of the upper valley. Small waterfalls within these fjords are also used as freshwater resources. Hanging valleys also occur underwater in fjord systems. The branches of Sognefjord are for instance much shallower than
12502-426: The majority of the ice sheet, which is located below the sea level. Its collapse would cause ~3.3 m (10 ft 10 in) of sea level rise. This disappearance would take an estimated 2000 years. The absolute minimum for the loss of West Antarctica ice is 500 years, and the potential maximum is 13,000 years. Once ice loss from the West Antarctica is triggered, the only way to restore it to near-present values
12635-497: The marine limit. Like freshwater fjords, the continuation of fjords on land are in the same way denoted as fjord-valleys . For instance Flåmsdal ( Flåm valley) and Måbødalen . Outside of Norway, the three western arms of New Zealand 's Lake Te Anau are named North Fiord, Middle Fiord and South Fiord. Another freshwater "fjord" in a larger lake is Western Brook Pond , in Newfoundland's Gros Morne National Park ; it
12768-507: The melting of Greenland ice sheet would most likely add around 6 cm ( 2 + 1 ⁄ 2 in) to sea levels under the low-emission scenario, and 13 cm (5 in) under the high-emission scenario. The first scenario, SSP1-2.6 , largely fulfils the Paris Agreement goals, while the other, SSP5-8.5, has the emissions accelerate throughout the century. The uncertainty about ice sheet dynamics can affect both pathways. In
12901-568: The most expensive projects ever attempted. Most ice on Greenland is in the Greenland ice sheet which is 3 km (10,000 ft) at its thickest. The rest of Greenland ice forms isolated glaciers and ice caps. The average annual ice loss in Greenland more than doubled in the early 21st century compared to the 20th century. Its contribution to sea level rise correspondingly increased from 0.07 mm per year between 1992 and 1997 to 0.68 mm per year between 2012 and 2017. Total ice loss from
13034-405: The most extreme cases, there is a constant barrier of freshwater on the surface and the fjord freezes over such that there is no oxygen below the surface. Drammensfjorden is one example. The mixing in fjords predominantly results from the propagation of an internal tide from the entrance sill or internal seiching. The Gaupnefjorden branch of Sognefjorden is strongly affected by freshwater as
13167-569: The mountainous regions, resulting in abundant snowfall to feed the glaciers. Hence coasts having the most pronounced fjords include the west coast of Norway, the west coast of North America from Puget Sound to Alaska, the southwest coast of New Zealand, and the west and to south-western coasts of South America , chiefly in Chile . Other regions have fjords, but many of these are less pronounced due to more limited exposure to westerly winds and less pronounced relief. Areas include: The longest fjords in
13300-628: The observed ice-sheet erosion in Greenland and Antarctica had matched the upper-end range of the AR5 projections by 2020, and the finding that AR5 projections were likely too slow next to an extrapolation of observed sea level rise trends, while the subsequent reports had improved in this regard. Further, AR5 was criticized by multiple researchers for excluding detailed estimates the impact of "low-confidence" processes like marine ice sheet and marine ice cliff instability, which can substantially accelerate ice loss to potentially add "tens of centimeters" to sea level rise within this century. AR6 includes
13433-506: The observed sea level rise and its reconstructions from the historical geological data (known as paleoclimate modeling). It was developed because process-based model projections in the past IPCC reports (such as the Fourth Assessment Report from 2007) were found to underestimate the already observed sea level rise. By 2013, improvements in modeling had addressed this issue, and model and semi-empirical projections for
13566-473: The ocean gains heat, the water expands and sea level rises. Warmer water and water under great pressure (due to depth) expand more than cooler water and water under less pressure. Consequently, cold Arctic Ocean water will expand less than warm tropical water. Different climate models present slightly different patterns of ocean heating. So their projections do not agree fully on how much ocean heating contributes to sea level rise. The large volume of ice on
13699-543: The ocean surface, effects of climate change on the water cycle can even increase ice build-up. However, this effect is not enough to fully offset ice losses, and sea level rise continues to accelerate. The contributions of the two large ice sheets, in Greenland and Antarctica , are likely to increase in the 21st century. They store most of the land ice (~99.5%) and have a sea-level equivalent (SLE) of 7.4 m (24 ft 3 in) for Greenland and 58.3 m (191 ft 3 in) for Antarctica. Thus, melting of all
13832-448: The ocean was about 150 m (490 ft) at Notodden . The ocean stretched like a fjord through Heddalsvatnet all the way to Hjartdal . Post-glacial rebound eventually separated Heddalsvatnet from the ocean and turned it into a freshwater lake. In neolithic times Heddalsvatnet was still a saltwater fjord connected to the ocean, and was cut off from the ocean around 1500 BC. Some freshwater fjords such as Slidrefjord are above
13965-401: The other hand, the whole EAIS would not definitely collapse until global warming reaches 7.5 °C (13.5 °F), with a range between 5 °C (9.0 °F) and 10 °C (18 °F). It would take at least 10,000 years to disappear. Some scientists have estimated that warming would have to reach at least 6 °C (11 °F) to melt two thirds of its volume. East Antarctica contains
14098-454: The others are sinking. Since 1970, most tidal stations have measured higher seas. However sea levels along the northern Baltic Sea have dropped due to post-glacial rebound . An understanding of past sea level is an important guide to where current changes in sea level will end up. In the recent geological past, thermal expansion from increased temperatures and changes in land ice are the dominant reasons of sea level rise. The last time that
14231-423: The outlet follow the Norwegian naming convention; they are frequently named fjords. Ice front deltas developed when the ice front was relatively stable for long time during the melting of the ice shield. The resulting landform is an isthmus between the lake and the saltwater fjord, in Norwegian called "eid" as in placename Eidfjord or Nordfjordeid . The post-glacial rebound changed these deltas into terraces up to
14364-439: The outlet of fjords where submerged glacially formed valleys perpendicular to the coast join with other cross valleys in a complex array. The island fringe of Norway is such a group of skerries (called a skjærgård ); many of the cross fjords are so arranged that they parallel the coast and provide a protected channel behind an almost unbroken succession of mountainous islands and skerries. By this channel, one can travel through
14497-465: The place name Fiordland . The use of the word fjord in Norwegian, Danish and Swedish is more general than in English and in international scientific terminology. In Scandinavia, fjord is used for a narrow inlet of the sea in Norway, Denmark and western Sweden, but this is not its only application. In Norway and Iceland, the usage is closest to the Old Norse, with fjord used for both a firth and for
14630-651: The poorly observed areas. A more complete observational record shows continued mass gain. In spite of the net mass gain, some East Antarctica glaciers have lost ice in recent decades due to ocean warming and declining structural support from the local sea ice , such as Denman Glacier , and Totten Glacier . Totten Glacier is particularly important because it stabilizes the Aurora Subglacial Basin . Subglacial basins like Aurora and Wilkes Basin are major ice reservoirs together holding as much ice as all of West Antarctica. They are more vulnerable than
14763-556: The preindustrial levels. Since the Last Glacial Maximum , about 20,000 years ago, sea level has risen by more than 125 metres (410 ft). Rates vary from less than 1 mm/year during the pre-industrial era to 40+ mm/year when major ice sheets over Canada and Eurasia melted. Meltwater pulses are periods of fast sea level rise caused by the rapid disintegration of these ice sheets. The rate of sea level rise started to slow down about 8,200 years before today. Sea level
14896-507: The projected range for total sea level rise was 9.5–16.2 metres (31–53 ft) by the year 2300. Projections for subsequent years are more difficult. In 2019, when 22 experts on ice sheets were asked to estimate 2200 and 2300 SLR under the 5 °C warming scenario, there were 90% confidence intervals of −10 cm (4 in) to 740 cm ( 24 + 1 ⁄ 2 ft) and − 9 cm ( 3 + 1 ⁄ 2 in) to 970 cm (32 ft), respectively. (Negative values represent
15029-563: The rest of East Antarctica. Their collective tipping point probably lies at around 3 °C (5.4 °F) of global warming. It may be as high as 6 °C (11 °F) or as low as 2 °C (3.6 °F). Once this tipping point is crossed, the collapse of these subglacial basins could take place over as little as 500 or as much as 10,000 years. The median timeline is 2000 years. Depending on how many subglacial basins are vulnerable, this causes sea level rise of between 1.4 m (4 ft 7 in) and 6.4 m (21 ft 0 in). On
15162-458: The same approaches to adapt to sea level rise as richer states. Between 1901 and 2018, the global mean sea level rose by about 20 cm (7.9 in). More precise data gathered from satellite radar measurements found an increase of 7.5 cm (3.0 in) from 1993 to 2017 (average of 2.9 mm (0.11 in)/yr). This accelerated to 4.62 mm (0.182 in)/yr for 2013–2022. Paleoclimate data shows that this rate of sea level rise
15295-641: The same regions typically are named Sund , in Scandinavian languages as well as in German. The word is related to "to sunder" in the meaning of "to separate". So the use of Sound to name fjords in North America and New Zealand differs from the European meaning of that word. The name of Wexford in Ireland is originally derived from Veisafjǫrðr ("inlet of the mud flats") in Old Norse, as used by
15428-426: The same. The same estimate found that if the temperature stabilized below 2 °C (3.6 °F), 2300 sea level rise would still exceed 1.5 m (5 ft). Early net zero and slowly falling temperatures could limit it to 70–120 cm ( 27 + 1 ⁄ 2 –47 in). By 2021, the IPCC Sixth Assessment Report was able to provide estimates for sea level rise in 2150. Keeping warming to 1.5 °C under
15561-404: The sea caused by currents and detect trends in their height. To measure the distance to the sea surface, the satellites send a microwave pulse towards Earth and record the time it takes to return after reflecting off the ocean's surface. Microwave radiometers correct the additional delay caused by water vapor in the atmosphere . Combining these data with the location of the spacecraft determines
15694-476: The sea-surface height to within a few centimetres. These satellite measurements have estimated rates of sea level rise for 1993–2017 at 3.0 ± 0.4 millimetres ( 1 ⁄ 8 ± 1 ⁄ 64 in) per year. Satellites are useful for measuring regional variations in sea level. An example is the substantial rise between 1993 and 2012 in the western tropical Pacific. This sharp rise has been linked to increasing trade winds . These occur when
15827-487: The seaward margins of areas with fjords, the ice-scoured channels are so numerous and varied in direction that the rocky coast is divided into thousands of island blocks, some large and mountainous while others are merely rocky points or rock reefs , menacing navigation. These are called skerries . The term skerry is derived from the Old Norse sker , which means a rock in the sea. Skerries most commonly formed at
15960-673: The specific regions. A structured expert judgement may be used in combination with modeling to determine which outcomes are more or less likely, which is known as "shifted SEJ". Semi-empirical techniques can be combined with the so-called "intermediate-complexity" models. After 2016, some ice sheet modeling exhibited the so-called ice cliff instability in Antarctica, which results in substantially faster disintegration and retreat than otherwise simulated. The differences are limited with low warming, but at higher warming levels, ice cliff instability predicts far greater sea level rise than any other approach. The Intergovernmental Panel on Climate Change
16093-414: The standard model, glaciers formed in pre-glacial valleys with a gently sloping valley floor. The work of the glacier then left an overdeepened U-shaped valley that ends abruptly at a valley or trough end. Such valleys are fjords when flooded by the ocean. Thresholds above sea level create freshwater lakes. Glacial melting is accompanied by the rebounding of Earth's crust as the ice load and eroded sediment
16226-419: The steady cooling of the surface and wind. In the deep fjords, there is still fresh water from the summer with less density than the saltier water along the coast. Offshore wind, common in the fjord areas during winter, sets up a current on the surface from the inner to the outer parts. This current on the surface in turn pulls dense salt water from the coast across the fjord threshold and into the deepest parts of
16359-453: The total sea level rise in his scenario would be in the range of 0.98–4.82 m (3–16 ft) by 2150. AR6 also provided lower-confidence estimates for year 2300 sea level rise under SSP1-2.6 and SSP5-8.5 with various impact assumptions. In the best case scenario, under SSP1-2.6 with no ice sheet acceleration after 2100, the estimate was only 0.8–2.0 metres (2.6–6.6 ft). In the worst estimated scenario, SSP-8.5 with ice cliff instability,
16492-455: The water column, increasing turbidity and reducing light penetration into greater depths of the fjord. This effect can limit the available light for photosynthesis in deeper areas of the water mass, reducing phytoplankton abundance beneath the surface. Overall, phytoplankton abundance and species composition within fjords is highly seasonal, varying as a result of seasonal light availability and water properties that depend on glacial melt and
16625-445: The water melts more and more of their height as their retreat continues, thus accelerating their breakdown on its own. This is widely accepted, but is difficult to model. The latter posits that coastal 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 rapidly collapse under their own weight once
16758-436: The world are: Deep fjords include: Sea level rise Between 1901 and 2018, the average sea level rose by 15–25 cm (6–10 in), with an increase of 2.3 mm (0.091 in) per year since the 1970s. This was faster than the sea level had ever risen over at least the past 3,000 years. The rate accelerated to 4.62 mm (0.182 in)/yr for the decade 2013–2022. Climate change due to human activities
16891-556: The year 2000. The Thwaites Glacier now accounts for 4% of global sea level rise. It could start to lose even more ice if the Thwaites Ice Shelf fails and would no longer stabilize it, which could potentially occur in mid-2020s. A combination of ice sheet instability with other important but hard-to-model processes like hydrofracturing (meltwater collects atop the ice sheet, pools into fractures and forces them open) or smaller-scale changes in ocean circulation could cause
17024-594: The year 2100 are now very similar. Yet, semi-empirical estimates are reliant on the quality of available observations and struggle to represent non-linearities, while processes without enough available information about them cannot be modeled. Thus, another approach is to combine the opinions of a large number of scientists in what is known as a structured expert judgement (SEJ). Variations of these primary approaches exist. For instance, large climate models are always in demand, so less complex models are often used in their place for simpler tasks like projecting flood risk in
17157-589: Was adopted in German as Förde , used for the narrow long bays of Schleswig-Holstein , and in English as firth "fjord, river mouth". The English word ford (compare German Furt , Low German Ford or Vörde , in Dutch names voorde such as Vilvoorde, Ancient Greek πόρος , poros , and Latin portus ) is assumed to originate from Germanic * ferþu- and Indo-European root * pertu- meaning "crossing point". Fjord/firth/Förde as well as ford/Furt/Vörde/voorde refer to
17290-450: Was almost constant for the last 2,500 years. The recent trend of rising sea level started at the end of the 19th or beginning of the 20th century. The three main reasons why global warming causes sea levels to rise are the expansion of oceans due to heating , water inflow from melting ice sheets and water inflow from glaciers. Other factors affecting sea level rise include changes in snow mass, and flow from terrestrial water storage, though
17423-407: Was considered even more important than the 2014 IPCC Fifth Assessment Report . Even more rapid sea level rise was proposed in a 2016 study led by Jim Hansen , which hypothesized multi-meter sea level rise in 50–100 years as a plausible outcome of high emissions, but it remains a minority view amongst the scientific community. Marine ice cliff instability had also been very controversial, since it
17556-509: Was due to greater ice gain in East Antarctica than estimated earlier. In the future, it is known that West Antarctica at least will continue to lose mass, and the likely future losses of sea ice and ice shelves , which block warmer currents from direct contact with the ice sheet, can accelerate declines even in East Antarctica. Altogether, Antarctica is the source of the largest uncertainty for future sea level projections. In 2019,
17689-472: Was proposed as a modelling exercise, and the observational evidence from both the past and the present is very limited and ambiguous. So far, only one episode of seabed gouging by ice from the Younger Dryas period appears truly consistent with this theory, but it had lasted for an estimated 900 years, so it is unclear if it supports rapid sea level rise in the present. Modelling which investigated
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