In September 2016, the surface of the Arctic sea ice shrank to nearly 4.1 million square kilometres – the second smallest recorded area since satellites started mapping sea ice. This result is second only to the 3.4 million square kilometres of sea ice recorded in 2012.
“This is again a massive loss of ice in the Arctic,” said Prof Lars Kaleschke of the University of Hamburg, in German. This was confirmed by Prof Christian Haas from the Alfred Wegener Institute (AWI), who said the trend continued, referring to the fact that the Northeast Passage and Northwest Passage are now simultaneously passable.
Every September, when the annual melt in the Arctic comes to an end, the sea ice that remains will be measured. This is an important indicator of climate change. In the winter of 2015 and 2016, the atmosphere was more than six degrees Celsius warmer than the long-term average in the Arctic Ocean, said Prof Kaleschke from the Center for Earth System Research and Sustainability (CEN) at the University of Hamburg. “Due to the higher temperatures, the ice growth is less.”
The thickness of the ice has been measured at different areas of the Arctic using high-resolution aircraft observations and measurements. Prof Haas described the newly formed, first-year ice as very thin, barely more than a metre thick. This was in contrast with the perennial ice in previous years, which was about three to four metres thick. This year, the ice loss was much delayed in June and July, but made its appearance in August due to strong winds.
The University of Hamburg and the AWI have jointly developed a new service issuing continuous ice thickness specifications. For the first time, the measurements of two ESA satellites – CryoSat and SMOS – were combined. “We were able to see the end of the Arctic winter. The ice was ten centimetres thinner than in previous years – a significant reduction,” said Prof Kaleschke.
The area of sea ice was measured using satellite data. Prof Kaleschke’s team managed to improve the process so as to allow an image to be captured within exactly three kilometres. Thus it can be seen as north of Alaska known as the Beaufort vortex the ice breaks up unusually early, in April. Based on the date, it was discovered that the area north of Alaska, known as the Beaufort vortex, had broken up unusually early, in April. In May and June, the sea ice area was actually smaller than ever. This year, there was another unusual detail: Many areas of open water were seen at the heart of the North Pole.
Since the end of August 2016, the Northeast Passage and Northwest Passage became largely free of ice. Yachts and a cruise ship took the opportunity to sail along the southern route of the Northwest Passage.
A crucial factor in the climate scenario, the Arctic sea ice serves as an early warning system for global warming. In the 1970s and 1980s, the minimum ice area in the summer still averaged about seven million square kilometres. According to Prof Kaleschke, the Arctic sea ice retreat was a clear indication that global warming remained unchecked.
Learn about the current sea ice development in the Arctic: www.meereisportal.de/