The Ayles Ice Shelf was one of six major ice shelves in Canada, all located on the northern coast of Ellesmere Island, Nunavut. The ice shelf broke off from the coast on August 13, 2005, forming a giant ice island thick and measuring around by in size (approximately 66 km² or 25.5 mi² in area or 2.6 km³ in volume). The oldest ice in the ice shelf is believed to be over 3,000 years old. The ice shelf was located at approximately south of the North Pole.
The Ayles Ice Shelf, like the nearby Mount Ayles, was named for the Arctic explorer Adam Ayles, who served under George Nares as the Petty Officer of HMS Alert in the British Arctic Expedition. A 1986 survey of Canadian ice shelves found that 48 square km (3.3 cubic km) of ice calved from the Milne and Ayles ice shelves between 1959 and 1974.
The breakup was noticed by the Canadian Ice Service at the time that it occurred, but it took a further 16 months to fully reconstruct the breakup sequence from past satellite images captured by MODIS, to determine the climatic conditions during the event, and for the event to garner public attention. The event, which some have linked to global warming, is similar to the 2002 breakup of the Larsen B Ice Shelf in Antarctica.
The speed of the breakup is also remarkable; it took less than an hour. Canada has lost approximately 90% of its ice shelves in the last hundred years.
Within days of the breakup, the former shelf had drifted over from Ellesmere Island before freezing into the sea ice for the winter. It was estimated in May, 2007 to be between 138 and 148 feet thick, on average.
The freed segment of the ice shelf, known as Ayles Ice Island, drifted southwesterly for two years, and in January 2007 accelerated into the open Arctic Ocean, causing concern for oil rig operators in the Beaufort Sea north of Prudhoe Bay. In August 2007, however, the island became wedged into the Sverdrup Inlet of the Queen Elizabeth Islands. Although scientists initially thought it was likely to remain there for some time, possibly permanently, it soon afterwards broke into two parts and resumed movement.
There is concern that the ice islands may become a hazard for ships and oil platforms.
While the formation of the Ayles Ice Island received widespread attention at the time due to the availability of satellite imagery and the ability of news media and scientists to visit the island, it was by no means unprecedented. On August 14, 1946, a U.S. Air Force patrol plane flying 300 miles north of Port Barrow, Alaska spotted an ice island, dubbed T-1, which was 15 miles wide and 18 miles across. It was estimated to be from 240 and 1600 feet thick, with sides that rose from 30 to 200 above the sea surface - much larger than the Ayles Ice Island. Over the following three years, it travelled 1500 miles along the Beaufort Eddy, a slow-moving ocean current that flows eastward across the North Pole, then back west along the coast. In 1950, the U.S. Air Force 58th Reconnaissance Squadron was ordered to find T-1, and any other ice islands in the Arctic. In July, 1950, T-2 was found, a roughly rectangular ice island estimated to be 20 miles by 20 miles by dimension. In 1947, a joint U.S.-Canadian expedition had noted and photographed a fresh water sea formation in the sea off Ellesmere Island. From a photographic examination of its ridges, T-2 was discovered to be the same ice island spotted off Ellesmere Island in 1947. Later in July 1950, the U.S. Air Force found T-3, a kidney-shaped island, nine by four and a half miles. This was later occupied for brief periods in the early and mid 1950s. In August 1951, T-1 was relocated, nestled along the coast of Ellesmere Island. It is not known how long prior T-1, T-2, and T-3 had been formed, but it is believed they had calved from ice shelves on northern Ellesmere Island. There are an estimated 80 ice islands in Canada's High Arctic, most of them part of the pack ice that covers the region.
Between August 1961 and April 1962, almost 600 square kilometres of ice broke away from the Ward Hunt Ice Shelf. This event was attributed to tidal and seismic events.