Department of the Environment and Heritage Annual Report 2003-04
Department of the Environment and Heritage, 2004
ISSN 1441 9335
Review of performance: Outcome 2 - Antarctica (continued)
Understanding the global climate system
Through Australia's Antarctic science programme, the Department is advancing understanding of Antarctica's role in the global climate system and contributes data to the world's climate research and meteorological communities.
In 2003-04, the Department's research covered a range of disciplines, notably:
- biology;
- glaciology; and
- space and atmospheric sciences.
The Australian Antarctic Division contributed to this output.
Antarctica and climate
Objective
To improve understanding of Antarctica's role in the global climate system.
This knowledge will help Australians plan for the challenges of global climate change and better understand the likely impacts on weather and climate, oceans and sea levels, and natural ecosystems. Some of the questions being addressed are:
- the role of Antarctic cryosphere (the region where water is found in its frozen form) in the global climate system and sea level change;
- the Southern Ocean processes responsible for climate variability and predictability, and how they influence sea level;
- the magnitude and current uptake of atmospheric carbon dioxide by the Southern Ocean and what processes control this;
- changes in the climate of Antarctica and the Southern Ocean and the links between these changes and the global climate system; and
- the role of the dynamics and composition of the whole atmosphere in climate processes and how these are changing.
Activities
Biology
Plants, animals and microbes (bacteria, viruses, protists and fungi) in the Antarctic are of global importance. Research is looking at the effects of global climate change on Antarctic biota, and the role of Antarctic biota in global biogeochemical cycles. Biota of the Antarctic region have evolved to survive, and often thrive, on the fringes of the harshest continent on the planet and in the ocean which surrounds it. Many Antarctic organisms are living at the limit of survival and are indicators of global environmental change.
Data from a new French-Australian collaboration showed carbon dioxide uptake in the Southern Ocean correlates dramatically with phytoplankton stocks. These data contributed significantly to the development of biogeochemical models of the Southern Ocean.
Dimethyl sulphide is a volatile trace sulphur gas produced by marine micro-organisms. Vented to the atmosphere, it produces particles onto which water vapour condenses to form clouds, thus influencing climate. The relative contributions of Antarctic sea ice organisms to the sulphur cycle were examined.
This study and those on the impacts of ultraviolet radiation, grazing, and damage by viruses will establish the role of key micro-organisms and stresses on them on the flux of reduced sulphur compounds.
Exopolysaccharide is complex sugar made by many microbes in the Antarctic marine environment. Low temperatures stimulate some bacteria in sea ice and seawater to produce exopolysaccharide. Investigations by scientists working for the Department indicate exopolysaccharide is linked to the level of iron in seawater - a factor affecting the productivity of phytoplankton.
Glaciology
Glaciologists working for the Department found that in the past three years a major glacier, Brown Glacier on Heard Island, had retreated 50 metres. The surface of the lower slopes of the glacier lost as much as 11 metres in height. Even up high where it is colder and changes are less obvious, the surface was found to have lowered by up to four metres.
Analysis of ice cores taken from Law Dome provided high resolution data able to resolve sub-annual and inter-annual variations in past climate through most of the Holocene (the last 20 000 years). This record provides evidence of atmospheric transport and large-scale climate in the Australian sector of the Southern Hemisphere and beyond. Variability in the climate record is correlated with the total amount of direct sunlight received on the earth and offers new evidence of a solar-climate link. On shorter timescales, the record also shows significant variability at a period that is correlated with the El Nino Southern Oscillation phenomenon.
Salinity and temperature measurements in the ocean cavity beneath the Amery Ice Shelf show a strong seasonal cycle indicative of the interactive feedbacks that occur between the ice shelf and ocean. The under-shelf water is modified by a combination of melt on the underside of the ice shelf, intrusion of saltier water formed during sea ice growth in Prydz Bay, and water currents from further north.
Scientists working for the Department analysed changes between the 1950s and the present in the thickness and duration of the seasonal cover of ice that forms on the coastal ocean near Davis and Mawson stations. There has been a trend at both stations for the date at which the ice reaches its maximum thickness to be delayed by about four to five days per decade. These changes are related to changes in weather patterns rather than ocean changes.
Glaciologists observed and investigated a system of longitudinal and transverse rifts in the front of the Amery Ice Shelf that are extending and will eventually calve a 25 by 25 kilometre iceberg from the shelf. The rifts are extending at as much as 10 metres per day, and the rift propagation rate was found to have a strong seasonal signal.
Space and atmospheric sciences
Atmospheric physicists working for the Department successfully predicted a large ozone hole over much of Antarctica from work involving a light detection and ranging instrument. Observations continued at Davis station, providing atmospheric wind and temperature characterisation throughout the stratosphere and mesosphere (10 to 90 kilometre altitude). The winter stratosphere over the Antarctic in 2003 was abnormally cold and this resulted in conditions that produced much greater ozone depletion than would be expected from a normal year.
The Davis 55 megahertz radar system made the first observations of polar mesosphere summer echoes from the Antarctic continent. Previous radar observations in the sub-Antarctic suggested that there may be a significant difference between the northern and southern hemispheres in the nature of these echoes and in the mesosphere itself. However, observations at Davis during the 2003-04 summer did not support this.
A full summer of observations of winds in the upper mesosphere and lower thermosphere (60 to 100 kilometre) was carried out in conjunction with Japanese and British collaborators using similar radars at Syowa and Rothera stations. At present, observations of some atmospheric tides in this region have been inconsistent with each other and with model results. This unique data set will allow scientists to define the characteristics of the semidiurnal (12 hourly) tide in this region more precisely and to study the cause of its variability.
Result
Glaciologists from the Australian Antarctic Division found evidence of a decline in the extent of Antarctic ice, with chemical signals from an ice core taken from Law Dome near Casey station indicating a diminution in the sea ice of around 20 per cent in the past 50 years.
Division scientists found that in the past three years a major glacier, Brown Glacier on Heard Island, had retreated 50 metres. The surface of the lower slopes of the glacier lost as much as 11 metres in height.
Atmospheric physicists from the Division successfully predicted a large ozone hole over much of Antarctica from work involving a light detection and ranging instrument.
Research into Southern Ocean biogeochemical processes showed carbon dioxide uptake correlates dramatically with phytoplankton stocks.
Report on performance information
Tables 50, 51, 52, 53, 54 and 55 report performance results against the indicators in the 2003-04 portfolio budget statements.
| Performance information(a) | Result |
|---|---|
| 'Quantify the role of sea ice communities in Southern Ocean biogeochemical processes and contribute to the development of biogeochemical models of the Southern Ocean.' | Ongoing work contributed to the development of biogeochemical models of the Southern Ocean through data from a French-Australian collaboration. |
| 'Elucidate the roles of grazing and viral infection on the vertical flux of carbon.' | A new French-Australian collaboration showed a dramatic correlation between carbon dioxide uptake in the Southern Ocean and phytoplankton stocks. These data contributed significantly to Southern Ocean modelling. |
| 'Establish the role of marine micro-organisms in the cycling and sequestration of iron in the Southern Ocean.' | Investigations showed that a complex sugar produced by bacteria at low temperatures is linked to the level of iron in seawater, and hence the productivity of phytoplankton. |
| 'Establish the role of marine micro-organisms in the net flux of reduced sulphur compounds to the atmosphere, including identification of the key organisms responsible for synthesis and utilisation of these compounds and the impact of ultraviolet light, grazing and viral destruction of these organisms.' 'Monitor concentrations of reduced sulphur compounds in the atmosphere and waters of the Southern Ocean.' |
The Department supported ongoing studies into the factors that affect how Antarctic marine micro-organisms produce large quantities of a gas called dimethyl sulphide, which affects Antarctic cloud formation and hence the climate. |
(a) The performance information from the portfolio budget statements is paraphrased in some cases to reduce length, and not always quoted verbatim as in the similar tables for Outcome 1.
| Performance information | Result |
|---|---|
| 'Produce high-resolution isotopic, sedimentological and palaeontological Plio-Pleistocene records from samples collected from glacial deposits in Antarctica and sub-Antarctic islands in order to understand the natural climate cycles of the past.' | Geological records of past climate change obtained by Australian participation in the Ocean Drilling Programme in Prydz Bay were published. Results from a joint survey with the Italian programme of the George V Land continental margin were published. Analysis of long sediment cores from the Wilkes Land margin, from lakes on Loewe Massif, and from lakes in the Vestfold Hills is continuing. |
| Performance information(a) | Result |
|---|---|
| 'Monitor and detect change in Antarctic and Southern Ocean climatic parameters.' | Ongoing field work conducted annually contributes to databases. |
| 'Improve meso-scale sea ice models of the Mertz Glacier Polynya and validate against field data.' | Sea ice models have been refined following polynya field work. |
| 'Assess links between Antarctic sea ice variability and Southern Hemisphere weather.' | Data were collected and passed to the Commonwealth Scientific Industrial Research Organisation (CSIRO) and Bureau of Meteorology for inclusion in weather models. |
| 'Establish relationship between past changes in the Law Dome ice cap and ice core inferred palaeoclimate parameters.' 'Extend the high resolution (seasonal) Law Dome climate record to about 2,000 years before present.' |
Analysis of ice cores taken from Law Dome has provided very high resolution data able to resolve sub-annual and inter-annual variations in past climate through most of the Holocene (the past 20 000 years). It offers new evidence of a solar-climate link. |
| 'Assess the impact of the Mertz Glacier Polynya on Adelie Bottom Water production.' | The true role of the Mertz Glacier Polynya on deep bottom water is still being assessed, as is its role in global ocean circulation. |
| 'Assess the relative mass of ice in different sectors of East Antarctica.' | Ongoing work is showing little change to the mass of ice covering East Antarctica. |
| 'Assess dynamics and ice mass budget of the Amery Ice Shelf-Lambert Glacier system.' | Analysis of salinity and temperature measurements in the ocean cavity beneath the Amery Ice Shelf show a strong seasonal cycle indicative of the interactive feedback that occurs between the ice shelf and ocean. |
| 'Update climatology of inter-seasonal variability in landfast sea-ice extent and thickness.' 'Monitor and analyse fluctuations in the physical characteristics of the ice sheet, ice shelves and glaciers.' |
Scientists working for the Department have analysed changes in thickness and duration - between the 1950s and present - of the seasonal cover of ice on the coastal ocean near Davis and Mawson stations. There is a trend at both stations for the date at which the ice reaches its maximum thickness to be delayed by four to five days per decade. These changes are related to weather patterns rather than ocean changes. Scientists also observed and investigated rifts in the front of the Amery Ice Shelf, while research in the summer of 2003-04 found Brown Glacier on Heard Island had retreated 50 metres. |
(a) The performance information from the portfolio budget statements is paraphrased in some cases to reduce length, and not always quoted verbatim as in the similar tables for Outcome 1.
| Performance information | Result |
|---|---|
| 'Continue development of a Global Climate System Model (GCSM) with nested regional model for climate simulation purposes to cover the Antarctic and Southern Ocean region.' | Work on a global climate system model is now an ongoing research goal being performed by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) Centre for Atmospheric Research as part of its contribution to the Antarctic Climate and Ecosystems Cooperative Research Centre. |
| 'Determine associations between past levels of atmospheric constituents, as determined from ice cores, to the corresponding broad meteorological situations that existed at those times.' | Ice core analysis continues to provide data for collaborative research conducted through the Antarctic Climate and ecosystems Cooperative Research Centre. |
| 'Participate actively in the Surface Ocean Lower Atmosphere Study (SOLAS).' | The Department actively participated in the Surface Ocean Lower Atmosphere Study. |
| 'Validate climate models by simulating Antarctic climate changes over various time-scales in the past and investigate possible future changes.' | Models are being developed from knowledge of past climate change derived from ice core analysis. |
| 'Deploy additional long-term automatic weather stations.' | The long-term automatic weather station programme continued, with data available at www.antcrc.utas.edu.au/argos/awswebsite/datapage.html. |
| 'Explain how the El Nino-Southern Oscillation phenomenon influences and is influenced by processes occurring in Antarctica.' 'Carry out comprehensive analysis of weather systems in the Antarctic region.' 'Investigate how the Antarctic and southern Australian regions might influence each other's weather and climate via synoptic-scale meteorological processes.' |
Considerable progress was made in investigating how the Antarctic and southern Australian regions might influence each other's weather and climate via synoptic-scale meteorological processes. |
| Performance information | Result |
|---|---|
| 'Continue to map the change in water properties between 1960 and 1990.' | This is an ongoing activity which advanced during the year. |
| 'Collect water property data along track between Hobart and Dumont D'Urville.' | Four return research transects were conducted from Hobart to Dumont D'Urville. |
| 'Recover and redeploy automated sediment trap moorings to determine carbon transport and inter-annual variability.' | The recovery and redeployment of automated sediment trap moorings continued with mixed success. Analysis of previous sample collections from the automated moored sediment traps and from shipboard incubation experiments were successful and led to eight publications in refereed international journals in 2003-04. |
| 'Estimate the transport of the Kerguelen Western Boundary Current.' | Conductivity, temperature and depth/hydrographic observations were completed as part of work to estimate the transport of the Kerguelen Western Boundary Current. |
| 'Estimate factors controlling the biological productivity of the Southern Ocean and the export of carbon to the deep ocean.' | Studies into photosynthesis, ultraviolet light and iron availability continued to improve understanding of carbon transport. |
| 'Continue ocean and coupled ocean-atmosphere cryosphere models for the prediction of climate variability and change.' | Modelling of the ocean-atmosphere cryosphere continued. |
(a) The oceanography programme is undertaken almost entirely by staff of the Commonwealth Scientific Industrial Research Organisation (CSIRO) using Australian Antarctic Division resources. Their products feed into the work of the Antarctic Climate and Ecosystems Cooperative Research Centre whose reports set out the results of oceanographic research (see www.antcrc.utas.edu.au).
| Performance information | Result |
|---|---|
| 'Operate Light Detecting and Ranging (LIDAR) equipment at Davis that together with optical spectrophotometers and radars will measure stratospheric and mesospheric properties to quantify temperature, wind, aerosol concentration and abundance of trace gases to determine their role in the middle atmosphere climate.' | Light detecting and ranging, radar and spectrophotometer observations continued at Davis station, providing atmospheric wind and temperature characterisations through the stratosphere and mesosphere (10 to 90 kilometre altitudes). Observations of the stratosphere and mesosphere allowed atmospheric physicists to successfully predict a large ozone hole. The abnormally cold winter stratosphere in 2003 resulted in more ozone layer depletion than normal. |
|
'Measure vertical extent and frequency of very high altitude clouds to understand the atmospheric processes occurring at high altitudes.' 'Describe vertical air mixing between lower and middle atmosphere above Davis.' 'Describe a climatology of planetary waves and tides above Davis.' |
The Davis 55 megaherz radar system made the first observations of polar mesosphere summer echoes from the Antarctic continent. Collaboration on radar observations with Japanese and British scientists at Syowa and Rothera stations yielded new information about the upper mesosphere and lower thermosphere (60 to 100 kilometres), which is challenging current theories and will improve understanding of atmospheric tides. |
| Appropriation | Estimated price | Revised price | Actual expenses |
|---|---|---|---|
| Understanding global climate system - Output 2.3 (departmental) | $20.747 million | $22.031 million | $21.832 million |
(a) See also the summary resource tables at the end of this 'Review of performance'.
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