Arctic ozone levels in never-before-seen plunge (BBC News)

Long a consideration in the Antarctic, ozone levels in the Arctic are now a cause for concern

By Richard Black 5 April 2011
Environment correspondent, BBC News, Vienna
Original article here

The ozone layer has seen unprecedented damage in the Arctic this winter due to cold weather in the upper atmosphere.

By the end of March, 40% of the ozone in the stratosphere had been destroyed, against a previous record of 30%.

The ozone layer protects against skin cancer, but the gas is destroyed by reactions with industrial chemicals.

These chemicals are restricted by the UN’s Montreal Protocol, but they last so long in the atmosphere that damage is expected to continue for decades.

“The Montreal Protocol actually works, and the amount of ozone-depleting gases is on the way down, but quite slowly,” said Geir Braathen, a senior scientist with the World Meteorological Organization (WMO), which co-ordinates ozone data globally.

“In the meantime, we have some winters that get much colder than before and also the cold periods last longer, into the spring,” he told BBC News.

“So it’s really a combination of the gases still there and low temperatures and then sunshine, and then you get ozone loss.”

Dr Braathen was one of a number of scientists presenting the findings at the European Geosciences Union (EGU) annual meeting in Vienna.

‘Sun screen’

The destructive reactions are promoted by cold conditions (below -78C) in the stratosphere.

While this is an annual occurrence in the Antarctic, where the annual depletion has garnered the term “ozone hole”, the Arctic picture is less clear, as here the stratospheric weather is less predictable.

This winter, while the Arctic was unusually warm at ground level, temperatures 15-20km above the Earth’s surface plummeted and stayed low.

“The low temperatures were not that different from some other years, but extended much further into March and April – in fact it’s still going on now,” said Farahnaz Khosrawi, an ozone specialist at the Meteorological Institute at Stockholm University, Sweden.

Another, Dr Florence Goutail from the French National Centre for Scientific Research (CNRS), put the 2010/11 winter in context.

“Usually in cold winters we observe that about 25% of the ozone disappears, but this winter was really a record – 40% of the column has disappeared,” she said.

The longer and colder Antarctic winters often see 55% of the ozone depleted.

However, this has hardly any impact on human health, as the region is largely uninhabited – only the southern tip of South America sometimes comes under the ozone hole.

But in the Arctic, the situation is different.

Over the last month, severe ozone depletion has been seen over Scandinavia, Greenland, and parts of Canada and Russia.

The WMO is advising people in Scandinavian countries and Greenland to look out for information on daily conditions in order to prevent any damage to their health.

Loss of ozone allows more of the Sun’s harmful ultraviolet-B rays to penetrate through the atmosphere. This has been linked to increased rates of skin cancer, cataracts and immune system damage.

“With no ozone layer, you would have 70 times more UV than we do now – so you can say the ozone layer is a sunscreen of factor 70,” said Dr Geir Braathen at World Meteorological Organization.

Snow fall

Ozone depletion is often viewed as an environmental problem that has been solved.

The Montreal Protocol, established in 1987, and its successor agreements have phased out many ozone-depleting chemicals such as the chlorofluorocarbons (CFCs) that used to be in widespread use as refrigerants.

Balloon used for Arctic ozone measurements Ozone data were captured using satellites and weather balloons

Use of some continues at a much lower level, with poorer developing countries allowed more time in which to switch away from substances essential to some of their industries.

But even though concentrations of these chemicals in the atmosphere are falling, they can endure for decades.

In polar regions, the concentration of ozone-depleting substances has only fallen by about 10% from the peak years before the Montreal Protocol took effect.

In addition, research by Markus Rex from the Alfred Wegener Institute in Germany suggests that winters that stand out as being cold in the Arctic stratosphere are getting colder.

“For the next few decades, the [Arctic ozone] story is driven by temperatures, and we don’t understand what’s driving this [downward] trend,” he said.

“It’s a big challenge to understand it and how it will drive ozone loss over coming decades.”

Projections suggest that the Antarctic ozone hole will not fully recover fully until 2045-60.

Large-scale assessment of the Arctic Ocean: significant increase in freshwater content since 1990s

Innovations report 25.03.2011 – Original article here

The freshwater content of the upper Arctic Ocean has increased by about 20 percent since the 1990s. This corresponds to a rise of approx. 8,400 cubic kilometres and has the same magnitude as the volume of freshwater annually exported on average from this marine region in liquid or frozen form.

This result is published by researchers of the Alfred Wegener Institute in the journal Deep-Sea Research. The freshwater content in the layer of the Arctic Ocean near the surface controls whether heat from the ocean is emitted into the atmosphere or to ice. In addition, it has an impact on global ocean circulation.

Around ten percent of the global mainland runoff flows into the Arctic via the enormous Siberian and North American rivers in addition to relatively low-salt water from the Pacific. This freshwater lies as a light layer on top of the deeper salty and warm ocean layers and thus extensively cuts off heat flow to the ice and atmosphere. Changes in this layer are therefore major control parameters for the sensitive heat balance of the Arctic. We can expect that the additional amount of freshwater in the near-surface layer of the Arctic Ocean will flow out into the North Atlantic in the coming years. The amount of freshwater flowing out of the Arctic influences the formation of deep water in the Greenland Sea and Labrador Sea and thus has impacts on global ocean circulation.

Dr. Benjamin Rabe from the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association and his colleagues have evaluated a total of over 5,000 measured salt concentration profiles. To measure the depth distribution of the salt concentration, researchers used sensors from ships or mounted sensors on large ice floes so the data were recorded during the ice drift through the Arctic Ocean. Furthermore, measured values from submarines were inputted in the analyses. Major portions of the data stem from expeditions during International Polar Year 2007/2008. “The well coordinated research programmes in the Arctic have substantially improved the database in these difficult to access areas,” reports Rabe, who will again sail to the central Arctic on the research vessel Polarstern in the coming summer. The dense network of observations in recent years made it possible for the first time to come up with a comparative assessment of the freshwater content in the Arctic Ocean.

Rabe and his colleagues have published the increase in the freshwater content between the periods 1992 to 1999 and 2006 to 2008 in the journal Deep-Sea Research. “The considerable changes in the upper water layers primarily comprise a decline in salt concentration,” says Rabe. Another, though minor, effect is that the low-salt layers are thicker than before. The freshwater content of the Arctic Ocean may rise due to increased sea ice or glacier melt, precipitation or river inputs. Less export of freshwater from the Arctic – in the form of sea ice or in liquid form – also results in a rise in the freshwater content. The authors of the study point to altered export of freshwater and altered inputs from near-coastal areas in Siberia to the central Arctic Ocean as the most probable reasons.

Dr. Michael Karcher from the Alfred Wegener Institute, co-author of the study, simulated the observed processes using the NAOSIM coupled ocean/sea ice model. The model experiments make it possible to study longer periods, i.e. to map times for which no measurement data are available. The model also supplies important insights into the causes of the rising and falling freshwater content and points out the great significance of the local wind field. Measurements and the model additionally show that the changes in the Arctic freshwater content encompass far larger areas than assumed to date.

The title of the original publication by Benjamin Rabe, Michael Karcher, Ursula Schauer, John M. Toole, Richard A. Krishfield, Sergey Pisarev, Frank Kauker, Rüdiger Gerdes and Takashi Kikuchi is: “An assessment of Arctic Ocean freshwater content changes from the 1990s to the 2006-2008 period“ and appeared in the journal Deep-Sea Research I 58 (2011) 173-185; doi:10.1016/j.dsr.2010.12.002 (http://dx.doi.org/10.1016/j.dsr.2010.12.002).

The Alfred Wegener Institute conducts research in the Arctic, Antarctic and oceans of the high and mid latitudes. It coordinates polar research in Germany and provides major infrastructure to the international scientific community, such as the research icebreaker Polarstern and stations in the Arctic and Antarctica. The Alfred Wegener Institute is one of the seventeen research centres of the Helmholtz Association, the largest scientific organisation in Germany.

Margarete Pauls | Quelle: Informationsdienst Wissenschaft
Weitere Informationen: www.awi.de

PALAOA, Antarctic underwater acoustic observatory, celebrates its fifth anniversary

Innovations-report.de 14.01.2011
Original article here

Live sounds of seals and whales from Antarctica

Click here to find out more!Listen live on the Internet to what’s going on under the Antarctic sea-ice. The Alfred Wegener Institute’s PALAOA underwater acoustic observatory has made this possible for over five years.

The acoustic observatory has been continuously recording sounds under the ice near Neumayer Station since 28 December 2005. It provides the world’s longest time series of civilian acoustic measurements, enabling researchers to study the presence and behaviour of animals under the Antarctic ice. This has led to many new findings on the distribution and behaviour of several whale and seal species.

Recording the underwater calls of marine mammals is one of the most promising methods to study distribution and seasonal migration of these animals in the ice-covered Antarctic. Visual sightings of marine mammals in Antarctic waters are rare since human access is limited and animals only occasionally surface to breathe. Acoustic recordings, on the other hand, can be made year round. By means of the PALAOA observatory, ocean acoustics experts from the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association have discovered that leopard and Ross seals populate Antarctic waters near Neumayer Station III.

For many sounds it is now known by what species they are produced and, in some cases, in what type of behavioural context they are produced. Such acoustic data can be used to derive information on the timing of mating and reproduction of the various species. Acoustic behaviour of leopard and Ross seals, for instance, shows that both species also reproduce in coastal Antarctic waters. Previously this was only known for Weddell and crabeater seals.

Inter-annual comparisons of acoustic data indicate that the timing of reproduction is linked to the availability of certain types of ice on which the animals give birth to their young. “Some seal species actually are acoustically present in the PALAOA recordings in the same calendar week every year,” Dr. Ilse van Opzeeland describes the surprisingly exact timing of the animals. Researchers at the Alfred Wegener Institute were astonished to hear humpback whales on the edge of the Antarctic continent, even in austral winter. The observatory has also recorded calls of Antarctic blue whales, thereby refuting the existing presumption that the largest animals living on Earth avoid ice-covered waters.

Even 50 years after the end of commercial whaling in Antarctica very little is known about the long-term population development of these nearly exterminated giant whales. Traditional counts based on sightings often record only a few of these marine mammals during an expedition over several months. The PALAOA data, on the other hand, contain blue whale vocalisation almost every day because the calls of these animals have a very great range extending to several hundred kilometres. Such information is extremely important to gain a general understanding of the behaviour, size and recovery of the stocks of large whales, which are still endangered in a variety of ways.

The loudest sounds recorded by PALAOA stem from iceberg collisions. About once a year giants the size of Berlin bump into each other or into the edge of the ice shelf. These create quite a racket in the Bremerhaven offices of the ocean acoustics specialists, whose daily work is accompanied by the live sounds from the Antarctic. Aside from their usefulness for research, the extraordinary sounds from the Antarctic Ocean have also found their way into radio and television as well as into the works of musicians, composers and creative artists. In 2010 more than three million visitors saw and heard the walk-on sculpture and sound installation “Iceberg PALAOA” floating on the Ruhr River in Essen – it represented one of the highlights of the European Capital of Culture “RUHR2010”.

Background:
PALAOA stands for PerenniAL Acoustic Observatory in the Antarctic Ocean and also means “whale“ in the ancient Hawaiian language. It is the only hydroacoustic observatory in the immediate vicinity of the Antarctic continent, or more exactly on the Ekström Ice Shelf in the eastern Weddell Sea at 70°31’S 8°13’W. In December 2005, several hydrophones and sensors were positioned under the ice through holes drilled through the floating, 100 meter thick ice shelf around 25 kilometres north of the German Neumayer Station. Continuous recording of the underwater sounds for a period of several years enables unique acoustic observation of the underwater animal world. The recordings are made year-round and enable comparisons of the acoustic environment between years. In terms of energy, PALAOA is self-sufficient: solar cells and a wind generator supply the observatory with renewable energy 90% of the time. During the months of darkness in the Antarctic winter and at temperatures down to 50°C, a fuel cell driven with methanol springs into action on windless days to guarantee continuous operation. The acoustic observatory has recorded more than 30,000 hours (6 terabytes) of data in the past five years and registers a broad range of frequencies. This means PALAOA detects the low-frequency sounds of blue whales as well as the high-frequency clicks produced by orcas, that function as a biological echo sounder for orientation. Alongside acoustic data, oceanographic data, the movement of the ice shelf and sea ice and local shipping traffic are recorded in order to study their influence on the behaviour of the large marine mammals. Researchers hope to collect data for several more years until the ice shelf on which PALAOA is located breaks off and moves around the southern continent as a drifting iceberg.

You will find examples of sounds and valuable information on PALAOA on the Internet at: http://www.awi.de/de/aktuelles_und_presse/hintergrund/palaoa_wie_klingt_
das_suedpolarmee
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The recordings are transmitted via a WLAN and satellite link directly to Bremerhaven and can be heard as a livestream here: http://www.awi.de/PALAOA

The Alfred Wegener Institute conducts research in the Arctic, Antarctic and oceans of the high and mid latitudes. It coordinates polar research in Germany and provides major infrastructure to the international scientific community, such as the research icebreaker Polarstern and stations in the Arctic and Antarctica. The Alfred Wegener Institute is one of the sixteen research centres of the Helmholtz Association, the largest scientific organisation in Germany.

Margarete Pauls | Quelle: Informationsdienst Wissenschaft
Weitere Informationen: www.awi.de