Arctic Ocean this summer
Credit: Florian Breier-Alfred Wegener Institute
A international team of scientists have found the Arctic Ocean ice has been growing ever thinner — accompanied by changes in marine life and disturbing shifts in deep ocean currents.
A scientific expedition that spent the past two-and-half-months taking measurements across the Arctic reported this week that vast pans of ice measure only one meter thick — suggesting a 50 percent decrease in overall ice thickness since 2001.
These results were gathered by some of the 50 scientists from 10 countries aboard the research vessel Polarstern, sponsored by the German-based Alfred-Wegener Institute for Polar and Marine Research.
“The ice cover in the North Polar Sea is dwindling, the ocean and the atmosphere are becoming steadily warmer, the ocean currents are changing,” said chief scientist Dr Ursula Schauer, in a story posted on-line.
The observations surfaced amid a flurry of other climate-change news, highlighted by a Perfect Melt that shrank Arctic sea ice to the smallest extent ever reserved. As of Sept. 10, an area the size of California was free of ice cover for the first time in history, according to the lastest dispatch from the National Snow and Ice Data Center.
Meanwhile, U.S. climate monitors reported the Northern Hemisphere simmered through its warmest January-to-August period since the 1880s. And the Chukchi Sea village of Kivalina — one of the Alaska communities facing dangerous erosion due storm waves that build on an ocean that lacks protective ice — was evacuating some residents in advance of a big storm.
The expedition is one of the most ambitious in recent years, with the goal of getting unprecedented data about how the ice and its life are changing in real time.
The most recent release from the Alfred Wegener Institute offered more detail on the thinning ice:
Amongst other things, they have found out that not only the ocean currents are changing, but community structures in the Arctic are also altering. Autonomous measuring-buoys have been placed out, and they will contribute valuable data, also after the expedition is finished, to the study of the environmental changes occurring in this region.
Amphipods below the sea-ice.
Credit: Florian Breier/Alfred Wegener Institute“We are in the midst of phase of dramatic change in the Arctic, and the International Polar Year 2007/08 offers us a unique opportunity to study this dwindling ocean in collaboration with international researchers” said Schauer.
Changes in Sea-Ice
The thickness of the arctic sea-ice has decreased since 1979, and at the moment measures about a metre … in the central Arctic Basin.
In addition, oceanographers have found a particularly high concentration of melt-water in the ocean and a large number of melt-ponds.
These data, collected from on board the Polarstern, and also from helicopter flights allow the scientists to better interpret their satellite images.
Sea-Ice biologists from the Institute of Polar Ecology at the University of Kiel are studying the animals and plants living in and beneath the ice.
They are using the opportunity to investigate the threatened ecosystem. According to the newest models, the Arctic could be ice free in less than 50 years in case of further warming. This may cause the extinction of many organisms that are adapted to this habitat.
Ocean Currents
The Arctic Ocean currents are an important part of global ocean circulation. Warm water masses flowing in from the Atlantic are changed in the Arctic through water cooling and ice formation, and sink to great depths.
Scientists taking cores of sea-ice to determine
the thickness. They found it had lost 50 percent
of its thickness in six years.
Credit: Florian Breier/Alfred Wegener InstituteConstant monitoring by the Alfred-Wegener-Institute for Polar and Marine Research over the last ten years have recorded significant changes, and have demonstrated a warming of the incoming current from the Atlantic Ocean.
During this expedition, the propagation of these warming events along each of the currents in the North Polar Sea will be investigated. The large rivers of Siberia and North America transport huge amounts of freshwater to the Arctic. The freshwater appears to function as an insulating layer, controlling the warmth transfer between the ocean, the ice and the atmosphere.
The study area stretches from the shelf areas of the Barents Sea, the Kara Sea and the Laptev Sea, across Nansen and Amundsen bays right up to Makarow Bay.
Between Norway and Siberia and up to the Canadian Bay the scientists have taken temperature, salinity, and current measurements at more than 100 places.
First results have shown that the temperatures of the influx of water from the Atlantic are lower as compared to previous years. The temperatures and salinity levels in the Arctic deep sea are also slowly changing. The changes are small here, but the areas go down to great depths, and enormous water volumes are therefore involved.
In order to follow the circulation patterns in winter, oceanographic measuring buoys will be attached to ice floes, and continuous measurements will be taken whilst they float along with the ice. The measurements will be relayed back via satellite.
In addition to the ocean currents and sea-ice, zooplankton, sediment samples from the sea floor as well as trace elements will be taken. Zooplankton are at the base of the food chain for many marine creatures, and are therefore an important indicator for the health of the ecosystem.
The deposits found on the ocean floor of the North Polar Sea read like a diary of the history of climate change for the surrounding continents. Through sediment cores, the scientists may be able to unlock the key to the glaciation of northern Siberia.
In addition, the members of the expedition will be able to measure trace elements from Siberian rivers and shelf areas, that through polar drift are being pushed towards the Atlantic.
