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Global warming threatens Atlantic cod stocks

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Atlantic cod are facing climate change pressure.

New study to take close look at climate impacts to commercially important cod fishery

By Summit Voice

FRISCO — With Atlantic cod already moving into waters around Spitsbergen — into Arctic cod territory — fisheries biologists are keeping a close eye the commercially important species to determine the consequences of climate-related migrations. Specifically, researchers want to how how the fish are responding to warmer and more acidic water, and at which stages of life the changes are most dangerous to them.

In the next two and a half years, biologists from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, together with scientists from Kiel, Bremen, Düsseldorf and Münster, will study all life stages of the fish and their genetic patterns: from spawn and the development of the larvae, through the juvenile fish and their favorite food, the copepod, to the mature parent fish. Continue reading

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Antarctic clams may take a hit from global warming

Study shows climate change may affect overall population numbers

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Changes in Antarctic clam populations could have a ripple effect on other species in the region like these blue-eyed cormorants in the South Shetlands. Bob Berwyn photo.

By Summit Voice

FRISCO — Warming ocean temperatures and increased glacial outflow around Antarctica may have a big impact on clams living on the ocean floor. Younger clams try to move away when they sense warmer temperature or reduced oxygen levels, but older clams stay put.

The findings by a team of British and German scientists indicate how climate change may affect biodiversity in the region, suggesting that the overall population of Antarctic clams may dwindle, since it’s the older animals that reproduce.

“Our study shows that the physiological flexibility of young clams diminishes as they get older. However, the species has evolved in such a way that the fittest animals, that can tolerate life in an extreme environment, survive to reproduce into old age,” said Doris Abele, of the Alfred Wegener Institute in Germany. “Climatic change, affecting primarily the older clams, may interfere with this evolutionary strategy, with unpredictable consequences for ecosystems all around Antarctica.” Continue reading

Climate: German researchers document dramatic Arctic ecosystem changes linked with melting sea ice

On a voyage

On a voyage to the central Arctic Ocean, German researchers documented significant changes to marine ecosystems linked with melting Arctic sea ice. Photo courtesy Alfred Wegener Institute.

Massive algae blooms change composition of sea floor food chain

By Summit Voice

SUMMIT COUNTY — Arctic Ocean ecosystems are sure to change in as-yet unexpected ways as sea ice continues to shrink. This summer, German Polar researchers and microbiologists documented one of those changes, observing an unprecedented bloom of ice-loving algae on patches of thin summer ice.

The researchers hypothesized three years ago that ice algae could grow faster under the thinning sea ice of the Central Arctic. This past summer’s observations support the hypothesis: The ice algae were responsible for almost half of the primary production in the Central Arctic Basin. The paper is published in the journal Science.

“We were able to demonstrate for the first time that the warming and the associated physical changes in the Central Arctic cause fast reactions in the entire ecosystem down to the deep sea,” said Lead researcher Dr. Antje Boetius, of the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research. Continue reading

Climate: Arctic ice melting from ‘the inside-out’

Tarns speed melting of ice cap

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Young sea ice is more susceptible to melting from within. Photo courtesy Stefan Hendricks, Alfred Wegener Institute.

FRISCO — German scientists say they’ve discovered another positive global warming feedback which could cause Arctic sea ice to melt faster than anticipated. During recent research expeditions in the Arctic they’re observed a large number of melt ponds on the surface, covering about half of the one-year ice.

“The ice cover of the Arctic Ocean has been undergoing fundamental change for some years. Thick, multi-year ice is virtually nowhere to be found any more,” said Marcel Nicolaus, of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research.

“Instead, more than 50 percent of the ice cover now consists of thin one-year ice on which the melt water is particularly widespread. The decisive aspect here is the smoother surface of this young ice, permitting the melt water to spread over large areas and form a network of many individual melt ponds,” Nicolaus said.

By contrast, the older ice has a rougher surface which has been formed over the years by the constant motion of the floe and innumerable collisions. Far fewer and smaller ponds formed on this uneven surface which were, however, considerably deeper than the flat ponds on the younger ice.

As part of their research, sea ice physicists at the institute have now measured the light transmission through the Arctic sea ice for the first time on a large scale, enabling them to quantify consequences of this change. In areas where melt water collects on the ice, far more sunlight and therefore energy is able to penetrate the ice than is the case for white ice without ponds. That means the ice is absorbing more solar heat, is melting faster, and more light is available for the ecosystems in and below the ice. The findings have been published inGeophysical Research Letters.

“We knew that an ice floe with a thick and fresh layer of snow reflects between 85 and 90 per cent of sunlight and permits only little light through to the ocean. In contrast, we could assume that in summer, when the snow on the ice has melted and the sea ice is covered with melt ponds, considerably more light penetrates through the ice,” he said.

To find out the extent to which Arctic sea ice permits the penetration of the sun’s rays and how large the influence of the melt ponds is on this permeability, the researchers equipped a remotely operated underwater vehicle with radiation sensors and cameras. In the summer of 2011 during an Arctic expedition of the research ice breaker POLARSTERN, they sent this robot to several stations directly under the ice. During its underwater deployments, the device recorded how much solar energy penetrated the ice at a total of 6000 individual points all with different ice properties.

“The young thin ice with the many melt ponds does not just permit three times as much light to pass through than older ice. It also absorbs 50 per cent more solar radiation. This conversely means that this thin ice covered by melt ponds reflects considerably fewer sun rays than the thick ice. Its reflection rate is just 37 percent. The young ice also absorbs more solar energy, which causes more melt. The ice melts from inside out to a certain extent,” Nicolaus said.

“We assume that in future climate change will permit more sunlight to reach the Arctic Ocean … particularly that part of the ocean which is still covered by sea ice in summer … The greater the share of one-year ice in the sea ice cover, the more melt ponds will form and the larger they will be.

“This will also lead to a decreasing surface albedo and transmission into the ice and ocean will increase,” he said. “The sea ice will become more porous, more sunlight will penetrate the ice floes, and more heat will be absorbed by the ice. This is a development which will further accelerate the melting of the entire sea ice area.”

However, at the same time the organisms in and beneath the ice will have more light available to them in future. Whether and how they will cope with the new brightness is currently being investigated in cooperation with biologists.

The problem with long-term weather forecasting …

German researchers say more observational data from Arctic is needed

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Understanding the dynamic processes of the Arctic could help generate more accurate long-term forecasts for the mid-latitudes.

By Summit Voice

FRISCO — While some observable atmospheric and ocean patterns can help forecasters predict general weather patterns on a seasonal basis, meteorologists and climatologists are still from from being able to predict the intensity of winter weather or drought a year or two in advance.

Long-term forecasts would be invaluable to energy and agriculture sectors, for example, but German climate researchers recently concluded that here is still a long way to go before reliable regional predictions can be made on seasonal to decadal time scales.

After evaluating 23 climate models, the researchers said none of them is able to forecast the weather-determining patterns of high and low pressure areas to the degree  that the probability of a cold winter or a dry summer can be reliably predicted. Continue reading

Environment: Plastic pollution showing up in the Arctic Sea

Sea water off the east coast of Greenland looked a bit like marbled paper in October 2012. The shifting swirls of white were sea ice, as observed by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite on October 17, 2012. In fact, this ice moved discernibly between October 16 and October 17. Thin, free-drifting ice moves very easily with winds and currents. Click the image for more info from the NASA Earth Observatory.

German study finds litter on the seafloor in the Fram Strait

By Summit Voice

SUMMIT COUNTY — Underwater cameras used primarily to track ecological changes on the floor of the Arctic Sea have helped German researchers quantify increases in the amount of plastic waste in the region. In some places, concentrations of garbage are higher than those found in a deep-sea canyon near Lisbon, Portugal.

“The main victims of the increasing contamination of the seafloor are the deep-sea inhabitants,” said Dr. Melanie Bergmann, biologist and deep-sea expert at the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association. “Almost 70 percent of the plastic litter that we recorded had come into some kind of contact with deep-sea organisms. For example we found plastic bags entangled in sponges, sea anemones settling on pieces of plastic or rope, cardboard and a beer bottle colonised by sea lilies,” Bergmann said. Continue reading

Shrinking sea ice affecting Arctic Ocean top to bottom

Researchers find less thick, multi-year ice and show that the dwindling ice pack will have impacts deep in the sea, and not just at the surface

The Polarstern in the central Arctic. Photo courtesy Stefan Hendricks, Alfred-Wegener-Institut.

By Summit Voice

SUMMIT COUNTY — Researchers aboard the Polarstern say findings from their two-month Arctic cruise helps confirm satellite data showing that Arctic sea ice is not only shrinking, but quickly growing thinner.

The research also helps show how the seasonal changes in Arctic ice extent are not restricted to the visible surface, but have impacts to Arctic Ocean biological communities all the way to the sea floor. Continue reading

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