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Greenland ice core project

The Greenland Ice Core Project (GRIP) was a research project organized through the European Science Foundation (ESF). The project ran from 1989 to 1995, with drilling seasons from 1990 to 1992. In 1988, the project was accepted as an ESF-associated program, and the fieldwork was started in Greenland in the summer of 1989.

GRIP aimed to collect and investigate 3000-meter-long ice cores drilled at the apex of the Greenland ice sheet, also known as Summit Camp. The Greenland ice sheet comprises more than 90% of the total ice sheet and glacier ice outside Antarctica.

The project was managed by a Steering Committee of the University of Bern's Physics Institute, chaired by Professor Bernhard Stauffer. Funding came from eight European nations (Belgium, Denmark, France, Germany, Iceland, Italy, Switzerland, and the United Kingdom), and from the European Union. Studies of nuclear isotopes and various atmospheric constituents provided by the cores allowed the team to construct detailed records of climate change, covering the last 100,000 years.

Background
The loss of mass of the Greenland ice sheet has been accelerating due to the effects of climate change caused by human activities. The mass loss of ice sheets and glaciers causes sea levels to rise, terrestrial albedo to decline, and patterns of ocean circulation to change. It is predicted that the sea level will rise by approximately 7 meters if all the ice melts. The rise in sea levels due to ice sheet glaciers’ melt would make it impossible for people to live in coastal regions.

Because there is no preserved ancient terrestrial sediment in Greenland, most ice sheet history is based on indirect records. Using the limited paleoclimate data, researchers have shown that the extent of ice in Greenland has changed significantly over time, and this suggests that the change in size is due to a variety of physical environmental factors. The best estimates based on the paleoclimate data show that the Greenland ice sheet is significantly reduced by even a small increase in the negative effects of climate change. A 2020 research paper suggests that the melting of the ice sheet that covers Greenland will accelerate much faster than previously predicted.

Results and findings
Studies of nuclear isotopes and various atmospheric constituents provide detailed records of climate change over 100,000 years. From the analysis of the oxygen isotope ratio of the GRIP core excavated in 1992, it became clear that abrupt climate change occurred in Greenland during the last glacial period. This happened more than 20 times. It further became clear that the warm and cold periods alternated. Near the bottom of the GRIP core, oxygen isotope ratios fluctuated sharply; this was initially interpreted as an indication of repeated violent climate change during the last interglacial period in Greenland.

Techniques
The first drilling of the Greenland Ice Core Project went only a few hundred meters into the glacier ice. But from 1989 to 1992 GRIP successfully drilled a 3029-meter ice core to the bed of the Greenland ice sheet at Summit (72.579°N, -37.56533°W). In 1991, ice cores 783 to 2482 meters long were drilled, and an ice core was drilled to bedrock in 1992. The ice core was first taken to the University of Copenhagen in Denmark, where it was stored in a cold room at -26 °C. Five sections of ice core with a length of about 300 to 400 mm were shipped to Japan. A wide range of information related to past and present climatic and environmental changes can be analyzed from the ice. The glacier layers that are collected can reveal up to 500,000 years of evidence.

Studies of isotopes and various atmospheric constituents in the core have provided a detailed record of climate variability reaching more than 100,000 years back in time. The results indicate that the Holocene climate was remarkably stable, but they confirm the occurrence of rapid climatic variation during the last ice age. Delta-O-18 variations observed in the core that are believed to date from the Eemian Stage have not been confirmed by other records, including the North Greenland core, and are no longer believed to represent climate events. The interglacial climate of the Eemian Stage appears to have been as stable as the Holocene.

Three different types of ice sheet core drills were used in the project, differing mainly in the depths they can drill to.

Hand auger
The hand auger weighs 80 kg, can be operated by a single person, and is useful for collecting ice cores with a diameter of 74 mm from the top 10 m of the ice cap.

Shallow drill
The shallow drill can take cores up to 50 m long and 74mm in diameter from the top 350 m of ice, and it does not require drilling fluid.

Deep drill
The deep drill works in liquid-filled holes, can retrieve the core, and can be operated at any depth. Compared to other drills, the operation is relatively slow.

Related projects
In addition to GRIP, there have been several other ice core projects in Greenland, such as the Greenland Ice Sheet Project (GISP2), the North Greenland Ice Core Project (NorthGRIP), and the North Greenland Eemian Ice Drilling (NEEM).

Greenland Ice Sheet Project (GISP2)
Initially GISP2 seemed to overturn an earlier result discovered by GRIP. Based on the sharp fluctuations of the oxygen isotope ratio near the bottom of the GRIP core, it had been hypothesized that severe climate change occurred repeatedly during the last interglacial period in Greenland. However, the oxygen isotope ratio data of the GISP2 core that was excavated only 30 km away from the sampling point of the GRIP core did not match the GRIP data. It became clear that the ice layer structure was disturbed by folds at the bottom of the ice sheet in both cores, indicating that the interpretation that there was severe climate change during the final interglacial period may be incorrect.

The GISP2 reconstructions are relatively old. Recent studies have raised questions about evaluating the relationship between temperature and Delta-O-18 during the Holocene in view of the elevation changes in the ice cap at the GISP2 site. The GISP2 reconstructions changed the relationship between Delta-O-18 and temperature by a factor of two during the Holocene, while more recent reconstructions leave that relationship unchanged. Elevation change affects the Delta-O-18 record, and the older GISP2 reconstructions do not account for elevation changes.

NorthGRIP
NorthGRIP aimed to collect ice during the final interglacial period, but the bottom of the ice sheet had melted, and it was not possible to excavate those samples. As a result, temperatures estimated to be as high as 5 °C above those at present were observed from some of the ice cores that could be collected in the middle of the last interglacial period; the Greenland ice sheet apparently existed even in such a warm climate.

The shaded lines represent the uncertainty of the estimates due to inaccuracies in the analysis and adjustments in the isotope model.

The North Greenland Eemian Ice Drilling (NEEM)
The later NEEM project extended the work of GRIP by excavating an ice core that shows the bottom melting and the folds at the NEEM site, and provides evidence concerning the entire final interglacial period. In Northern Greenland, it was warmest around 126,000 years before the beginning of the last interglacial period, when the temperature was about 8 °C ± 4 °C higher than it is now. During the 6000 years between 128,000 and 122,000 years ago, the ice sheet thickness decreased by 400 ± 250 m, and 122,000 years ago the ice sheet surface altitude was 130 ± 300 m higher than it is today. This shows that it is extremely rare for the ice sheet to melt even in the hot summer in Greenland. Rather, the ice sheet surface melted during the final interglacial period (the Eemian) because of the methane and rare gases collected from NEEM's ice core. The fact that the Greenland core remained stable during the temperature rise suggests that the Antarctic ice sheet shrank during the final interglacial period and contributed significantly to the increase in sea level.

Climate change
To accurately predict the response of the Greenland ice sheet to climate change, it is necessary to obtain long-term data on past warming and its effects and improve the climate and ice sheet models based on it. Since anthropogenic factors are deeply involved in environmental issues such as greenhouse gases, they may also be related to climate change during the Eemian.

EastGRIP
Previous ice core drilling projects, including GRIP, were carried out at sites where horizontal ice flow is as small as possible. In contrast, the latest EastGRIP research was conducted upstream of the Northeast Greenland Ice Stream. This is the most significant active ice stream in Greenland.

In addition, the ice depths in the earlier Greenland ice cores that corresponded to the warm period of the early Holocene were very fragile. It was almost impossible to collect highly accurate chemical and gas analysis data with high time resolution from the traditional Greenland ice cores. In view of this difficulty, EastGRIP installed a cold temperature chamber to keep the drilled ice below -30 °C immediately after the drilling, and efforts were made to minimize the destruction of ice cores by eliminating small steps of several tens of microns in the core field processing. The cold air prevents the expansion of air bubbles and keeps the ice from breaking. As a result, ice cores capable of continuous flow analysis have been acquired even from fragile depth zones, and it is expected that more detailed and accurate analysis of gas and other chemicals will be possible in the future.

Other projects

 * East Greenland Ice-core Project (EastGRIP)
 * WAIS Divide Ice Core Project
 * DYE3
 * Camp Century
 * South Pole Ice Core Project
 * Arctic Ice Core Project

title: Greenland ice core project


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Riad al-Turk

Riad al-Turk (رياض الترك; 17 April 1930 – 1 January 2024) was a Syrian opposition leader, a political prisoner for about 20 years, and supporter of democracy, who was called "the Old Man of Syrian opposition." He was secretary general of the Syrian Communist Party (Political Bureau) from its foundation in 1973 until 2005.

Overview
Al-Turk joined the Syrian Communist Party while a student. He was imprisoned for the first time in 1952 shortly after finishing law school for opposing the military government that came to power in a coup. He was held for five months and tortured but never tried in court. He later wrote articles for the party newspaper, Al-Nour, and became a leading party ideologue. He was imprisoned again in 1958 under Nasser for opposing the merger of Syria and Egypt in the United Arab Republic and held for sixteen months. Again he was tortured but not tried for any crime.

Turk had for some time been leading a faction within the Communist Party that demanded a more positive view of Arab nationalism, in opposition to Secretary-General Khalid Bakdash, who ruled the party with an iron fist. In 1972, Bakdash decided to merge the party into the National Progressive Front, a coalition of organizations allied with the ruling Arab Baath Socialist Party. Along with supporters on the radical wing of the party, Turk formed the Syrian Communist Party (Political Bureau), consolidating a split that had been apparent since the late 1960s. The SCP-Political Bureau initially negotiated with the government for terms of legalization and membership in the Front. However, it later took a strong opposition stance, especially from 1976 on after the Syrian intervention in favour of the Maronites right-wing government in the Lebanese Civil War. This led to repression of the party, which was stepped up at the beginning of the 1980s when the Hafez al-Assad government felt itself under increasing pressure from both Islamists and the secular opposition. Al-Turk was arrested and imprisoned on 28 October 1980 and held under very difficult conditions for almost 18 years. He spent most of this period in solitary confinement and suffering regular torture. Based on interviews with al-Turk journalist Robin Wright reports he was "locked way in a windowless underground cell, about the length of his body or the size of a small elevator compartment, at an intelligence headquarters." Al-Turk was "never allowed out of his cell to exercise. Until the final months, he was not allowed a book, newspaper, mail or anything else to keep his mind occupied." For the first thirteen years of his imprisonment he was allowed no communication from, or information about, his friends and family, including his two young daughters. His "only activity was being allowed three times a day to go to a shared toilet." He was never allowed to use it when other prisoners were there but did scrounge the toilet bin for discarded clothing as his own clothing was worn out. One of his few diversions was collecting grains of dark cereal he found in the thin soup he was served in the evening and using the grains to create pictures in his cell. He suffered considerable ill-health, including diabetes for which he was refused treatment. He was released on 30 May 1998.

After his release in 1998, al-Turk was initially not particularly active politically. In June 2000, however, Syrian president Hafiz al-Asad died and his son Bashar succeeded him. This was followed by an outburst of political debate and demands for democratic changes, known as the Damascus Spring, and al-Turk resumed a prominent role. His statement on al Jazeera television in August 2001 that "the dictator has died" was seen as a direct cause of renewed repression by an angered government, and al-Turk himself was arrested some days later on September 1, 2001, subjected to a trial widely seen as unfair before a state security court. In June 2002 he was sentenced to three years imprisonment for `attempting to change the constitution by illegal means. This led to international protests, especially given his poor health.

Al-Turk was released after serving fifteen months of his sentence, and resumed his political activities. In spring 2005 the Syrian Communist Party (Political Bureau) held a secret congress at which it decided to change its name to the Syrian Democratic People's Party. At this congress, Turk stepped down as party secretary, but he remained an influential member of the organization. In the same year, he also emerged as a prominent name in the Damascus Declaration, a pro-democracy coalition of Syrian opposition activists and organizations.

In 2011, he welcomed the onset of the Syrian revolution against Bashar al-Assad's regime. However, the country descended into civil war. Initially supporting an alliance under the National Council of all opposition currents, including Islamists, Riyad al-Turk later expressed regret, acknowledging the oversight of ignoring certain violations committed by Islamist groups during the emergency. By 2013, he had been living in seclusion, confined to an apartment in Damascus. Reflecting on his decades-long involvement with the Syrian Communist Party, al-Turk revealed to Le Monde: "Since I joined in the 1950s, clandestine life has been a tradition. My generation understands the importance of secrecy against such a regime. The young revolutionaries were unaware, and they paid a steep price." His wife left the country at the conflict's onset and died in Canada in 2017. Despite initial reluctance, al-Turk eventually yielded to the persuasion of his daughters, who were already refugees abroad. In late July 2018, he went into exile, passing through Turkey, and eventually settling in Paris, France.

Al-Turk died on 1 January 2024, at the age of 93.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Riad al-Turk


text: Category:Mercedes-Benz engines

title: Category:Mercedes-Benz engines


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Guillermo Rawson

Guillermo Rawson (24 June 1821 – 20 January 1890) was a medical doctor and politician in nineteenth-century Argentina. In 1862, when he was the Interior Minister of Argentina, he met Captain Love Jones-Parry and Lewis Jones, who were on their way to Patagonia to investigate whether it was suitable for the creation of a Welsh settlement there. Rawson came to an agreement with them, and this resulted in the creation of a colony in the Chubut Valley in the following years. The city of Rawson, the capital of the province of Chubut, was named after him.

Biography

Rawson's parents were Amán Rawson, a doctor who had emigrated from the United States to Argentina, and Justina Rojo, a daughter of a wealthy family in San Juan, where Guillermo was born. His elder brother was the artist Franklin Rawson. His half-brother was Lieutenant Colonel Juan de Dios Rawson, grandfather of Arturo Rawson.

After a Jesuit education in San Juan, Rawson graduated from the Medical Faculty of University of Buenos Aires in 1844. Rawson became interested in politics and democracy. In 1853, he was jailed for opposing Nazario Benavidez, the caudillo or de facto governor of San Juan. The following year he was a member of the Paraná Congress, and from 1862, he was Interior Minister in the government of Bartolomé Mitre.

Apart from politics, Rawson was interested in medicine and hygiene. In 1876, he attended the Centennial Exposition in Philadelphia to present his work on public health in Buenos Aires, the most developed body of work on the subject at the time. In 1879, he was elected a member of the American Antiquarian Society.

Rawson spent a year in Paris in 1881 for medical treatment, before returning to Argentina. He returned to France for further treatment in 1885 and died in Paris in 1890.

The building of the first medical school in Buenos Aires is named Escuela Dr Guillermo Rawson in his honour.

title: Guillermo Rawson