Few continuous observations of Antarctic climate are available before the International Geophysical Year of 1957-58. Since this time, surface temperatures have remained fairly stable over much of Antarctica, although individual station records show a high level of year-to-year variability, which could mask any underlying long term-trend.

The majority of stations in East Antarctica, including the two long-term records from the high plateau of East Antarctica (South Pole and Vostok) show no statistically-significant warming or cooling trends1. By contrast, large and statistically-significant warming trends are seen at stations in the Antarctic Peninsula, such as Faraday Station (aka Vernadsky Station) which this documentary will be visiting.

During International Polar Year (2008-2009), an unprecedented amount of research has been conducted on Antarctica. This report highlights some of these findings made by the scientific community the world over.

The Antarctica Challenge will profile these new findings from the research stations based there and manned by British, Russian and Ukrainian teams.

Over the past 50 years, the west coast of the Peninsula has been one of the most rapidly-warming parts of the planet. Here, annual mean temperatures have risen by nearly 3°C, with the largest warming occurring in the winter season^1,2,3. This is approximately 10 times the mean rate of global warming, as reported by the Intergovernmental Panel on Climate Change (IPCC). The east coast of the Peninsula has warmed more slowly and here the largest warming has taken place in summer and autumn³.

Significant warming has also been observed in the Southern Ocean. Upper ocean temperatures to the west of the Antarctic Peninsula have increased by over 1°C since 1955⁴. Within the circumpolar Southern Ocean, it is now wellestablished that the waters of the Antarctic Circumpolar Current (ACC) are warming more rapidly than the global ocean as a whole. A comparison of temperature measurements from the 1990s with data from earlier decades shows a large-scale warming of around 0.2°C in the ACC waters at around 700- 1100 m depth²¹.

Analysis of weather balloon data collected over the past 30 years has shown that the Antarctic atmosphere has warmed below 8 km and cooled above this height. This pattern of warming in the troposphere and cooling in the stratosphere is seen globally and is the expected signature of increases in greenhouse gases, such as carbon dioxide. However, the 30-year warming at 5 km over the Antarctic during winter (0.75°C) is over three times the average rate of warming at this level for the globe as a whole⁵.

Reliable year-round measurements of Antarctic sea ice extent are only available from the 1970s, when satellite observations first became available. Unlike in the Arctic, where there has been a significant decline in observed sea ice extent over this period, there has been a small but statistically-significant increase in the overall extent of Antarctic sea ice. However, there are strong geographical variations at a regional scale. Sea ice cover has declined substantially in the seas to the west of the Antarctic Peninsula while it has increased in other parts of the Antarctic⁶.

Subtle but important changes have occurred in the atmospheric circulation around Antarctica. Since the early 1960s, atmospheric pressure has dropped over Antarctica and risen in the mid-latitudes of the Southern Hemisphere, a pattern of variability known as the Southern Hemisphere Annular Mode (SAM)⁷. These changes have resulted in a strengthening of the westerly winds that blow over the Southern Ocean around Antarctica. Stronger westerlies will impact on ocean currents, upwelling and mixing, but the consequences of such changes have yet to be fully understood.

Recent climate change has driven significant changes in the physical and living environment of the Antarctic. Environmental change is most apparent in the Antarctic Peninsula, where climate change has been largest.

Adélie penguins, a species well adapted to sea ice conditions, have declined in numbers and been replaced by open-water species such as chinstrap penguins⁸.

Melting of perennial snow and ice covers has resulted in increased colonisation by plants⁹.

A long-term decline in the abundance of Antarctic krill in the SW Atlantic sector of the southern ocean may be associated with reduced sea ice cover¹⁰.

Large changes have occurred in the ice cover of the Peninsula. Many glaciers have retreated¹¹ and around 10 ice shelves that formerly fringed the Peninsula have been observed to retreat in recent years¹² and some have collapsed completely.

Furthermore, 87% of glaciers along the west coast of the AP have retreated in the last 50 years, and in the last 12 years most have accelerated. The Antarctic Peninsula is contributing to sea-level rise, at about the same rate as Alaska Glaciers.

Analysis of global measurements of atmospheric CO₂ indicates that the Southern Ocean carbon sink has weakened significantly since 1981. This reduction in the capacity of the ocean to absorb CO₂ has been attributed to increased upwelling of carbon-rich waters associated with strengthening of the westerly winds¹⁹. Although future changes in the ability of the Southern Ocean to sequester CO2 are not completely known, this will be a key factor that helps shape global climate.

Climate can vary as a result of changes in forcing factors that affect the way energy is exchanged between the sun, the earth and space. These factors can be of natural origin (e.g. volcanic dust in the atmosphere, variations in solar output and variations in the Earth's orbit about the sun) or a result of human activity (e.g. increases in "greenhouse" gases such as carbon dioxide).

Additionally, complex interactions between atmosphere, oceans and sea ice can cause climate variability, particularly on a regional scale, over a timescale of years to decades. Attributing observed changes in climate to particular changes in forcing (or to natural variability) is a difficult process that can only be accomplished by bringing together reliable observations of past and present climate with the results of experiments carried out with sophisticated models of the climate system.

Attribution of Antarctic climate change is particularly difficult because of the relatively small number of instrumental climate records available from this region and the short length of the records.

As part of the work undertaken for the Fourth Assessment Report of the IPCC¹³, about 20 different climate models were run with historical changes to natural and anthropogenic forcing factors to simulate the climate of the 20th century. The simulated changes in Antarctic surface temperatures over the second half of the 20th century vary greatly from model to model with no single model reproducing exactly the observed pattern of change.

However, when results from all models are averaged, the resulting pattern of change bears some resemblance to that observed, with greatest warming in the Peninsula region and little change elsewhere²⁰.

This result suggests that some of the observed change may have an anthropogenic origin, but the lack of a clear and consistent response to changed forcing between models also suggests that much of the observed change in temperatures may be due to natural variability. The IPCC model experiments fail to reproduce some of the observed features, notably the rapid warming of the lower atmosphere.

These differences between modelled and observed changes could be used to argue against attributing change to anthropogenic forcing but some caution is called for as the models used may not adequately represent all of the complex processes that determine temperatures in the polar regions.

Most of the IPCC model experiments do simulate the observed strengthening of the circumpolar westerly winds, suggesting that this phenomenon is a robust response to changed climate forcing.

Further experiments have indicated that changes in anthropogenic forcings, particularly stratospheric ozone depletion and increases in greenhouse gases, have made the largest contribution to the strengthening of the westerlies^14,15.

Recent climate observations show that changes in the strength of the westerlies strongly influence temperature variations on the east coast of the Antarctic Peninsula¹⁶. Taken together, these two results suggest that a significant fraction of the recent observed changes in climate in this part of the Antarctic can be attributed to human activity with a reasonable degree of certainty.

Further support for this view comes from analysis of marine sediment records which enable us to examine how the extent of Antarctic Peninsula ice shelves has varied over time. While some of the smaller ice shelves in this region have periodically grown and decayed over the past 10,000 years¹⁷, the Larsen-B ice shelf appears to have been stable throughout this period until it collapsed suddenly in March 2002¹⁸.

This suggests that recent warm temperatures are exceptional within the context of the last 10000 years, making it unlikely that they can be explained by natural variability alone.

Many of the theories that seek to explain the circumpolar warming of the ACC also have the strengthening of the westerly winds as their root cause. Whilst there is not yet a clear consensus on which are the mechanisms that are most important, there is increasing evidence that a significant part of this change is ultimately driven by human activities²².

If we make assumptions about how greenhouse gas emissions are likely to change, we can use climate models to predict how Antarctic climate may respond over the coming century. Models predict a warming of a few degrees celsius over much of continental Antarctica.

However, as mean temperatures over most of the continent are well below freezing, even this warming will not greatly increase loss of ice from the continent through melting. Indeed, increases in snowfall resulting from a warmer atmosphere (which can hold more water vapour) may actually thicken the Antarctic ice sheets.

Warming is also predicted in and over the oceans surrounding Antarctica. As a result, sea ice cover may decline by around 25% (although there are considerable uncertainties associated with this prediction). Where warmer ocean waters come into contact with the continental ice sheets, loss of ice from the continent will be accelerated.

Although stratospheric ozone levels are predicted to recover as a result of implementation of the Montreal Protocol (and its subsequent revisions), model predictions indicate that the circumpolar westerly winds will continue to strengthen as the effects of increasing greenhouse gases outweigh those of reducing ozone.

The Ozone Hole over Antarctica is now as big as the continent of North America, according to satellite readings as recent as September, 2008.

The figures were released by the National Oceanic and Atmospheric Administration (NOAA) which has been monitoring the ozone layer since 1962.

Ozone, a type of molecular oxygen, forms a protective layer measuring between six and 30 miles in the stratosphere that absorbs harmful ultra-violet (UV) radiation from the sun.

Scientists from the British Antarctic Survey (BAS) were the first to discover in 1985 that ozone levels were declining and that a hole had appeared above Antarctica.

Hundreds of people will die because of increasing levels of ozone at street level, according to BAS scientists as of October 5, 2008.

A study by the Royal Society found ground levels of ozone, the pollutant caused when sunlight hits a mixture of gases in the air, have risen by six per cent per decade since the 1980s.

Although the ozone layer protects the planet at a higher level, at ground level it is damaging to human health.

Children, the elderly and asthmatics are particularly vulnerable to the pollutant which affects the lungs, nose and eyes and is worse on warm stagnant days. In 2003 some 1,582 UK deaths were attributed to ozone.

But the study projected that with more emissions in the future and climate change this will rise by 51 per cent resulting in 2,391 deaths in 2020.

In Antarctica, the ozone hole is directly responsible for the extinction of several species of insect life, while others have evolved at unprecedented rates to create a hormone that acts as “sunscreen” in order to survive this new environment.

Antarctic worms, sea spiders, urchins and other marine creatures living in nearshore shallow habitats are regularly pounded by icebergs. New data suggests this environment along the Antarctic Peninsula is going to get hit more frequently.

The Antarctica Challenge will film the icebergs in this area.

This change is due to an increase in the number of icebergs scouring the seabed as a result of shrinking winter sea ice.

Scientists from the British Antarctic Survey (BAS) will show how the rate of iceberg scouring on the West Antarctic Peninsula seabed is affected by the duration of winter sea ice, which has dramatically declined (in space and time) in the region over the last few decades due to climate warming.

This increase in iceberg disturbance on the seabed, where the majority of all Antarctic life occurs (80%), could have severe effects on the marine creatures living as deep as 500m underwater.

Lead author, Dr Dan Smale from BAS, says: “It has been suggested previously that iceberg disturbance rates may be controlled by the formation of winter sea ice, but nobody’s been able to go out and measure it before. We were surprised to see how strong the relationship between the two factors is.

During years with a long sea ice season of eight months or so, the disturbance rates were really low, whereas in poor sea ice years the seabed was pounded by ice for most of the year. This is because icebergs are locked into position by winter sea ice, so they are not free to get pushed around by winds and tides until they crash into the seabed.”

By using grids of small concrete markers on the seabed at three different depths for five years, BAS SCUBA divers were able to determine the frequency of iceberg scour by counting the number of damaged or destroyed markers annually.

Ice disturbance has been recognised as a driving force in the structure of the Antarctic seabed animal communities. Iceberg scouring damages areas of the seabed creating space for a high diversity of animals to use.

However, an increase in iceberg scour with the seabed would affect the type and number of marine creatures found on the seabed and is expected to cause changes in the distributions of key species.

The penguin population of Antarctica is under pressure from global warming, says a new scientific report. The reduction in sea ice is threatening four populations that breed on the Antarctic continent - the Emperor, Gentoo, Chinstrap, and Adélie penguins.

Climate warming is melting the sea ice and taking away precious nesting grounds on which some penguins raise their young. Food has become increasingly scarce because of warming in conjunction with overfishing.

Dr. David Ainley has been studying penguins in Antarctica since 1977 and recently reported that entire rookeries of penguins will gather for a short period of time before returning to their nests and feeding area and leave one penguin behind. That single penguin marches into the continent never to return.

Dr. Ainley and his team have returned these errant penguins to their rookery only to have them turn around and re-start their suicide march into the frozen continent.

The Antarctica Challenge is arranging to secure footage of this rare phenomenon that is believed to be linked to climate changes in the penguins’ habitats.

The Antarctic Peninsula is warming five times faster than the average rate of global warming and the vast Southern Ocean has warmed all the way down to a depth of 3,000m. Sea ice - ice that forms from sea water - covers 40 per cent less area than it did 26 years ago off the West Antarctic Peninsula.

This has led to reduced numbers of krill, the main source of food for Chinstrap Penguins. The number of Chinstraps decreased by as much as 30 to 66 per cent in some colonies, as reduced food has made it more difficult for the young to survive. It is the same story for Gentoo Penguins, who are increasingly dependant on the declining krill stocks as overfishing kills off their usual food sources.

The Emperor Penguin, the largest and most majestic penguin in the world, has seen some of its colonies halved in size over the past half century. Warmer winter temperatures and stronger winds have forced the penguins to raise their chicks on increasingly thinner sea ice. For many years sea ice has broken off early and many eggs and chicks have been blown away before they were ready to survive on their own.

In the northwestern coast of the Antarctic Peninsula, where warming has been the most dramatic, populations of Adélie Penguins have dropped by 65 per cent over the past 25 years. Not only has food become scarcer with the disappearance of sea ice, but the Adélie’s cousins, the Gentoos and Chinstraps have also invaded the region to take advantage of warmer temperatures. Scientists are concerned about the future of the Adélie Penguin, which needs land that is free of snow and ice to raise their young.

Recent studies have shown that stocks of krill in Antarctica have declined dramatically in recent years. The reason for this is likely to be a fall in the amount of sea ice in the winter months particularly in the Antarctic Peninsula region.

Krill numbers may have dropped by as much as 80% since the 1970s - so today's stocks are a mere one-fifth of what they were only 30 years ago. The decline in krill account for, in part, the decline in the numbers of some penguin species.

Dr Angus Atkinson from British Antarctic Survey, says: "This is the first time that we have understood the full scale of this decline. Krill feed on the algae found under the surface of the sea-ice, which acts as a kind of 'nursery'.

The Antarctic Peninsula, a key breeding ground for the krill, is one of the places in the world where there has been the greatest rise in temperatures due to global warming. This region has warmed by 2.5 degrees Celsius in the last 50 years (much more than the mean global rate), with a striking consequential decrease in winter sea-ice cover.

"We don't fully understand how the loss of sea-ice here is connected to the warming, but we believe that it could be behind the decline in krill."

There has been previous speculation that krill stocks might have decreased, based on smaller more localized surveys over shorter time periods. This new finding comes from data from nine countries working in Antarctica that pooled their separate data covering 40 Antarctic summers.

Another animal that feeds on the same phytoplankton food as krill, jelly-like colonial animals called salps that drift in the ocean currents have increased in the same time the krill have decreased.

This decline in krill will also make it more difficult for the great baleen whales to return to pre-exploitation levels following their decimation in numbers during the years from approximately 1925-1975.