The Arctic ice pack is the sea ice cover of the Arctic Ocean and its vicinity. The Arctic ice pack undergoes a regular seasonal cycle in which ice melts in spring and summer, reaches a minimum around mid-September increases during fall and winter. Summer ice cover in the Arctic is about 50% of winter cover; some of the ice survives from one year to the next. 28% of Arctic basin sea ice is multi-year ice, thicker than seasonal ice: up to 3–4 m thick over large areas, with ridges up to 20 m thick. As well as the regular seasonal cycle there has been an underlying trend of declining sea ice in the Arctic in recent decades. Sea ice has an important effect on the heat balance of the polar oceans, since it insulates the warm ocean from the much colder air above, thus reducing heat loss from the oceans. Sea ice is reflective of solar radiation, reflecting about 60% of incoming solar radiation when bare and about 80% when covered with snow; this is due to a feedback known as the albedo effect. This is much greater than the reflectivity of the sea and thus the ice affects the absorption of sunlight at the surface.
The sea ice cycle is an important source of dense "bottom water". When sea water freezes it leaves most of its salt content behind; the remaining surface water, made dense by the extra salinity and produces dense water masses such as North Atlantic Deep Water. This production of dense water is essential in maintaining the thermohaline circulation, the accurate representation of these processes is important in climate modelling. In the Arctic, a key area where pancake ice forms the dominant ice type over an entire region is the so-called Odden ice tongue in the Greenland Sea; the Odden grows eastward from the main East Greenland ice edge in the vicinity of 72–74°N during the winter because of the presence of cold polar surface water in the Jan Mayen Current, which diverts some water eastward from the East Greenland Current at that latitude. Most of the old ice continues south, driven by the wind, so a cold open water surface is exposed on which new ice forms as frazil and pancake in the rough seas.
Records of Arctic Sea ice from the United Kingdom's Hadley Centre for Climate Prediction and Research go back to the turn of the 20th century, although the quality of the data before 1950 is debatable. Reliable measurements of sea ice edge begin within the satellite era. From the late 1970s, the Scanning Multichannel Microwave Radiometer on Seasat and Nimbus 7 satellites provided information, independent of solar illumination or meteorological conditions; the frequency and accuracy of passive microwave measurements improved with the launch of the DMSP F8 Special Sensor Microwave/Imager in 1987. Both the sea ice area and extent are estimated, with the latter being larger, as it is defined as the area of ocean with at least 15% sea ice. A modeling study of the 52-year period from 1947 to 1999 found a statistically significant trend in Arctic ice volume of −3% per decade. A computer-based, time-resolved calculation of sea ice volume, fitted to various measurements, revealed that monitoring the ice volume is much more significant for evaluating sea ice loss than pure area considerations.
The trends from 1979 to 2002 have been a statistically significant Arctic sea ice decrease of −2.5% ± 0.9% per decade during those 23 years. Climate models simulated this trend in 2002; the September minimum ice extent trend for 1979–2011 declined by 12.0% per decade during 32 years. In 2007 the minimum extent fell by more than a million square kilometers, the biggest decline since accurate satellite data has been available, to 4,140,000 km2. New research shows the Arctic Sea ice to be melting faster than predicted by any of the 18 computer models used by the Intergovernmental Panel on Climate Change in preparing its 2007 assessments. In 2012, a new record low of about 3,500,000 km2 was reached. In the overall mass balance, the volume of sea ice depends on the thickness of the ice as well as the areal extent. While the satellite era has enabled better measurement of trends in areal extent, accurate ice thickness measurements remain a challenge. "Nonetheless, the extreme loss of this summer’s sea ice cover and the slow onset of freeze-up portends lower than normal ice extent throughout autumn and winter, the ice that grows back is to be thin".
As more and more of the sea ice is thinner first-year ice the greater effect storms have on its stability with turbulence resulting from major extratropical cyclones resulting in extensive fractures of sea ice. Arctic sea ice ecology and history Global warming Iceberg Polar ice cap Polynya Shelf ice Antarctic sea ice Global Sea Ice Extent and Concentration Sea ice extent graphs since 1979 Sea Ice Index NOAA Arctic Program "Ice-free Arctic could be here in 23 years" The Arctic ice sheet True color map, daily updates during summer
Phakamile Mabija was an African anti-Apartheid activist who died while in police custody in 1977. Phakamile Mabija lived in the Northern Cape; as a member of the Anglican Church's NOMAD team, he was a delegate in the National Youth Leadership Programme, a three and a half month training course initiated by the Anglican Church at the beginning of 1977. He was politically affiliated with the ANC, he was detained by the South African Police on 27 June 1977 for alleged involvement in an incident when African and Coloured commuters stoned public transport during a bus boycott in Galeshewe, South Africa. Mabija was due to appear in court on 8 July 1977 under charges under the Riotous Assemblies Act, 1956. Mabija died in detention on 7 the day before his scheduled court hearing, he plunged from the 6th floor of Transvaal Road police station in Kimberley. The Dean of Kimberley, as Vicar General, received the news in the absence of Bishop Graham Charles Chadwick (Mabija was a full-time youth worker in the Anglican Parish of St James, Galeshewe.
Upon his return, Chadwick took up the protest against Mabija's death and the continued detention of his clergy. White wooden crosses were planted on the lawn outside Kimberley's St Cyprian's Cathedral for each day that the detentions continued, church bells being rung in protest. Public outcry lead to an inquest into Phakamile Mabija's death, conducted by Amnesty International between August and September 1977. Assessed by Professor JA Oliver, a verdict was handed by JH Booysen, the magistrate, it was found. Therefore, nobody was deemed responsible for his death. During the Kimberley Security Police's testimony at the inquest, Colonel JD du Plessis alleged that the officer on duty at the time of Mabija's death opened a window to allow fresh air to ventilate the room, but they kept the windows shut. Sergeant Oscar Ntsiko corroborated with the Colonel's account, stating that he escorted Phakamile Mabija to the toilet, upon their return, he broke free and ran back into Officer Van der Merwe's office, where he jumped out of the open window.
The Northern Cape Security Police had with them an alleged ANC pamphlet which encouraged detainees to take their own lives as an act of terrorism to the state. District surgeon Dr. TC Robertson's results from the post-mortem identified a fractured skull as Mabija's cause of death. Dr. BA Mahler, the independent pathologist brought in for the inquest, identified cuts on Mabija's face, he maintained. During her TRC testimony, Phakamile Mabija's mother, Shirley Mabija recalled the last time she had seen her son, he had been detained for two week prior to his death. On 7 July 1977 Sergeants Ntsiko and Du Plessis brought Phakamile Mabija home in order to locate documents that the police wanted him to produce. After a brief exchange with his mother Shirley, the police took Mabija back to prison, he died that evening. In 2009 steps were taken to rename the Transvaal Road Police Station in Mabija's memory, when Transvaal Road, Jones Street and Sidney Street, only Transvaal Road, in Kimberley would become known as Phakamile Mabija Road.
The renaming of Transvaal Road and Jones Street in Kimberley, as Phakamile Mabija Road, was marked by a ceremony held on Heritage Day 24 September 2011, following a commemorative lecture the previous evening. The city had named a street for Mabija, namely Phakamile Mabija Street, off Albert Luthuli Street, off John Daka, west of Otto's Kopje Mine. On the occasion of the renaming of Transvaal Road, in 2011, a memorandum was delivered at the Transvaal Road Police Station calling for it to be renamed "Phakamile Centre". Mabija was commemorated in the Northern Cape Department of Roads and Public Works initiative, the Phakamile Mabija Artisan Programme. Through this 2010-11 project 35 learners were placed at COEGA member companies in the Eastern Cape to receive working experience and access to further studies. A collective mural art project in Galeshewe, directed by Rochester Mafafu, vividly recalls the events surrounding Mabija's death; this was painted-over in 2013 but was subsequently restored by the artists Steve Biko Truth and Reconciliation Commission Allen, V. Mngqolo, S. & Swanepoel, S. 2012.
Stephen Mulvey was an Irish Gaelic footballer and revolutionary. His championship career with the Dublin senior team lasted one season. Mulvey first played competitive Gaelic football with the Bray Emmets club, he won his sole county senior championship medal in 1901. Mulvey made his debut on the inter-county scene as a member of the Dublin senior team during the 1902 championship, his one season with the team culminated with the winning of an All-Ireland medal, having earlier won a Leinster medal. As the political situation in Ireland became more militant, Mulvey joined the Irish Volunteers shortly after their establishment in 1913. During the 1916 Easter Rising he walked from his home in Bray to Dublin city centre to take part in the insurrection. Bray EmmetsDublin Senior Football Championship: 1901DublinAll-Ireland Senior Football Championship: 1902 Leinster Senior Football Championship: 1902