COMMEMORATIVE ISSUE

BAS Discoveries

Issue Date: Nov 99








The British Antarctic Survey (BAS) has undertaken research in the Antarctic on behalf of Britain for more than 50 years. During that time it has developed a closely integrated programme of environmental research in the life, earth and atmospheric sciences. Its objectives are to ensure that its research is of the highest international quality, addressing important science questions of global relevance that need to use the unique conditions found in Antarctica.

To do this BAS has created a very effective self-sufficient infrastructure in one of the most remote and hostile environments on earth. The five aircraft, two ships and three scientific research stations in the British Antarctic Territory provide the support essential for all the science, and the bases from which scientists and support staff can rise to the physical and mental challenges posed by the Antarctic environment.

British Antarctic Survey (BAS) is now well known to be a world-leader in environmental research. But behind each newsworthy science story, a team of scientists labour for the insight from which a science bite is distilled. The public are becoming increasingly familiar with the remarkable images of some of them.

The core of the BAS science programme lies in many disciplines: BAS continues to lead Antarctic research in many fields. Some of its most important and fundamental scientific contributions are illustrated in this series of stamps.

15p - Crustal microplates in West Antarctica
Scientist: Dr B C Storey

Antarctica has not always been the cold isolated polar continent that it is today. Two hundred million years ago and before, Antarctica was the centre of a large supercontinent known as Gondwana. For the most part, Gondwana broke up into the large southern hemisphere continents of South America, Africa, Australia and New Zealand. However, geological and geophysical data collected by joint UK-US-New Zealand expeditions to Antarctica over the past 10 years have shown that West Antarctica is actually a collage of five separate blocks which rotated as independent microplates during the break-up of Gondwana (illustrated on the stamp). The microplates are geologically different from each other and are separated by deep subglacial troughs. The Ellsworth Mountains is probably the most spectacular of these microplates. It rotated more than 90 degrees during the break-up process from an original position in Gondwana that was close to southern Africa. The reason why Gondwana broke up into these small fragments and why they amalgamated to form West Antarctica remains a geological puzzle.

30p - Lead levels in ice
Scientist: Dr Eric Wolf

In their upper layers, the polar ice sheets contain a detailed record of changes in the atmosphere over the industrial period. The remoteness of the polar regions means that ice core concentrations are an indication of the extent of long-range transport of pollutants. BAS research has provided some of the most notable contributions to this study. The research has been a technical challenge requiring the highest standards in sample collection in the Antarctic (such as illustrated on the stamp).

Typical lead concentrations in Antarctica (a few parts in 10 to the power of 12) are more than 1000 times lower than those usually measured in rivers and water supplies in Europe and North America. A new preconcentration technique was developed at BAS to allow samples to be analysed at these concentrations. BAS published the first reliable data for metal concentrations in Antarctic surface snow, with concentrations that are now accepted as being correct. The data showed that lead levels rose during the twentieth century reflecting the increased use of leaded fuel in petrol engines, but had fallen for the last two decades as unleaded fuels and especially biofuels were introduced into South America. Using the same techniques, new data were obtained for lead concentrations in Greenland snow. These gave the first hint that lead concentrations in Greenland snow were starting to fall in response to the increased use of unleaded fuels.

35p - Gigantism in marine invertebrates
Scientist: Professor Lloyd Peck

For the last hundred years, scientists believed that the phenomenon of giant species found in polar seas was related to the low temperatures and the reduced metabolic rates of the cold-blooded animals living there. However, BAS scientists working in collaboration with European colleagues, have found that the crucial fact is that the low sea water temperatures allow more oxygen to be disolved in the sea water than occurs at lower latitudes. This in turn means that the species living in polar waters have access to more oxygen, and a series of experiments has proved that this is the main reason that polar animals grow much larger than elsewhere. Examples are the decolopodid sea spiders (illustrated on the stamp) which have been known to grow over 30cm from leg tip to leg tip. Weight too is correspondingly larger; these sea spiders are over 1000 times heavier than most temperate species. Amphipod crustaceans in the Southern Ocean are also large; more than five times as long as the largest temperate species.

40p - The ozone hole
Scientists: Dr Joe Farman, Mr Brian Gardiner and Mr Jonathan Shanklin

Every year, during a seven-week period in the spring, the heart of the Antarctic ozone layer is nearly completely destroyed. In 1985, scientists of the British Antarctic Survey (BAS) announced the appearance of the Antarctic ozone hole and identified CFCs (chlorofluorocarbons) as the culprit. The spring destruction of ozone did not occur before the 1970s, but it is now expected to continue until at least the 2070s.

The discovery of the ozone hole was made possible by an extensive series of measurements which had been carried out by scientists of the British Antarctic Survey (BAS). Regular observations of Antarctic stratospheric ozone began in 1957 at Halley Station, and continue to this day, using a Dobson Spectrophotometer (illustrated on the stamp).

The discovery of the Antarctic ozone hole was the first unequivocal evidence of human activities affecting the atmosphere on a massive scale. This discovery was substantiated by a re-examination of satellite data and resulted in an intensive international campaign of research, led principally by the USA. The impact of this discovery was of sufficient magnitude to have been largely responsible for the successful and rapid negotiation of the Montreal Protocol on Substances that Deplete the Ozone Layer two years later. This made mandatory significant reductions in the use of chlorofluorocarbons and halons, thus demonstrating that science can, at times, influence rapidly and effectively the international political process.

70p - The electric field associated with the aurora
Scientists: Mr M Pinnock and Dr A S Rodger

The dynamic and dramatic aurora are observed at altitudes between 100-250 km above the Earth's surface. They occur in an ellipse that surrounds the magnetic poles in both hemispheres, being called the Aurora Borealis in the north and the Aurora Australis in the south. Because the magnetic pole is almost twice as far from the geographic pole in the south, compared with the north, Antarctica makes an ideal platform from which to study one of nature's most awe-inspiring phenomena. Aurora are caused by energetic particles impacting upon the Earth's upper atmosphere, and giving off mainly green and red light. As such the aurora act as a wonderful TV screen of processes many thousand of kilometres above the Earth's surface where the particles are accelerated to high energies. The particles which cause the aurora near noon come almost directly from the Sun. They provide a critical indicator of the weather in near-space, where storms can affect the routine operation of all types of satellites.

The antennas (illustrated on the stamp) are part of an over-the-horizon high frequency radar which can image the auroral processes over an area ten times the size of the UK in just two minutes. Data from the experiment, which is part of a major international network, have been used to provide much greater understanding of how the energetic particles from the Sun enter the Earth's atmosphere and cause rapid motions of the aurora through the effects of electric fields.

Acknowledgements: Text by Dr J Paten of British Antarctic Survey





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