Chapter Editor: John Turner
Authors: Robert Bindschadler, Pete Convey, Guido di Prisco, Eberhard Fahrbach, Dominic Hodgson, Paul Mayewski, Colin Summerhayes and John Turner
Great advances have been made in recent years into our understanding of Antarctic climate and environmental change. We now know that the climate system of the high southern latitudes is very complex and that there is variability on a range of time scales, with consequent effects on the terrestrial and marine biota. We also know that changes in the atmospheric and oceanic circulation around Antarctica, and the volume of the ice sheets, interact and influence climate at a global scale. Although a great deal of data are now available with which to investigate change – both in the past and over the next century, there are still major gaps in our knowledge and many areas where we require additional instrumental data gathering and model development.
The recommendations drawn together here summarise the conclusions we have reached in The instrumental period and The next 100 years, which if treated separately would have led to some duplication. Other recommendations can be found in Future developments in Antarctic observation, on specific observing system requirements, and in Concluding remarks on the pre-instrumental period, on research needed to improve the record of past climate change on geological time scales. In addition, scattered throughout the text there are many statements about additional research requirements.
- Collection of more in-situ data over the interior of the continent. AWSs are providing extremely valuable observations, but greater continuity in the observing programmes is needed and the maintenance of systems at selected sites for long periods. In addition to programmes describing Antarctic climatic variables at the macro-scale, there is an urgent need for the establishment of longer-term monitoring of biologically relevant microclimatic variables (as currently happens only during short-term biological studies), and the subsequent modelling effort to integrate patterns at the macro- and micro-scales.
- More traverses are required and more records extending back to at least 2000 years are needed at sites selected using information gained from ITASE efforts. Coastal ice core records not easily accessible by traverse need to be sampled, and there needs to be further international collaboration to ensure that coverage over the continent is as complete as possible.
- Continuity of space-based measurements is absolutely essential, since these are the sole major source of data for the whole of the continent and its surrounding ocean, where measurements on the ground or on the sea are difficult, dangerous, and not normally made year-round. We must not go blind to ice sheets at the very moment when their behaviour has started to become highly significant in relation to changes in sea level. Recommendations for satellite observations of the cryosphere are given in the Cryosphere Theme document produced for the Integrated Global Observing Strategy (IGOS) Partnership (http://www.eohandbook.com/igosp/cryosphere.htm).
- Improved satellite systems are required to help estimate the mass balance of the Antarctic as we are at the limit of the present technology.
- More observations of temperature, salinity, biochemical properties, such as oxygen and flow in the Southern Ocean are required. It is essential for observing instruments to be developed and deployed in greater numbers throughout the year and for long periods as part of a Southern Ocean Observing System (SOOS) so that long time series of key oceanographic parameters can be obtained with sufficient spatial coverage. Ship borne observations have to be complemented by those from autonomous systems.
- Intensified use of highly sophisticated marine equipment such as ROVs, AUVs, crawlers, gliders, landers, and remote underwater laboratories would contribute to a significant enhancement in understanding Antarctic ecosystem functioning, and, consequently, provide the basis for improved predictions of the marine ecosystem response to climate and other environmental changes. AUVs and sustained underwater measurements are also key to understanding ocean-ice interaction, which has emerged as a primary driver of recent (and therefore likely future) large ice mass losses.
- The markedly different behaviour of Antarctic sea ice in comparison to that found in the Arctic requires special efforts to obtain in-situ observations of Southern Ocean sea ice properties.
- The Southern Ocean continues to be under sampled with respect to carbon cycle related properties. The international CO2 community recommends for this region the construction of a CO2 ocean data observing system and delivery of CO2 ocean data products. Such data sets will provide valuable observational evidence for understanding historical climate change, and providing valuable insights into how the Southern Ocean may respond to further change. Such initiatives should be an integral component of the Southern Ocean Observing System required for monitoring and forecasting the ocean’s role in Antarctic climate change.
- In terms of simulating the Southern Ocean response to historical climate change, some of the largest uncertainties in our results lie in the hydrological cycle (especially precipitation), the most poorly observed of all the forcing fields. To better understand and quantify the changes due to historical and future climate change, better estimates of the freshwater budget will be required.
- Although there are many observational programmes concerned with change in the Antarctic ice sheet, we still have little data on permafrost and the active layer. The lack of long-term monitoring data precludes drawing any definitive conclusions on the impact of climate change on permafrost in Antarctica and this situation needs to be remedied through new observational initiatives.
- The last few years have also seen great advances in our understanding of terrestrial and marine ecosystems, and studies are now starting to address their resistance, resilience and adaptation to recent climate change. However, fundamentally important baseline biodiversity and biogeographic survey data are still lacking across most of the continent and parts of the surrounding Southern Ocean – those data and systematic and robust monitoring programmes across a network of representative locations are required to allow anything other than the current ad hoc and serendipitous approach to identifying biological responses to any aspect of environmental change in Antarctica. We also still require much more information on the links between the high latitude biota and broad-scale climatic factors, such as changes in the tropical atmosphere/ocean system (e.g. ENSO) and the modes of mid- and high latitude climate variability (e.g. the SAM).
- We recommend that the international community implement and monitor progress in the establishment of internationally recommended observing systems such as (a) CryOS (the Cryosphere observing system recommended for the IGOS Partners and adopted by the Group on Earth Observations), and (b) the Global Climate Observing System (GCOS).
- The Protocol on Environmental Protection to the Antarctic Treaty provides strict guidelines for the protection of the Antarctic environment and underscores its value to scientific research. Although rigorous application of the Protocol will help minimize the local impacts of both the tourism industry and national operators, constant vigilance is essential. Conservation measures should focus on achieving a better knowledge of the structure and functioning of Antarctic ecosystems and of the long-term effects of persistent contaminants in Antarctic organisms and food chains, and in developing continental-scale monitoring programmes based upon a network of carefully selected flagship sites.
- Higher horizontal and vertical resolution is needed in climate models to realistically represent many high latitude processes and their effects. Models must take into account in far greater detail than at present the complex orography in the coastal region, the behaviour of the atmospheric boundary layer, eddies in the ocean, and the effects of and sea ice. Sub-grid scale processes e.g. sea ice properties affecting atmosphere-ice-ocean interaction require improved parameterisations. Model outputs are also required at smaller physical scales relevant to the Antarctic habitats and communities, including the establishment and expansion of links between macro and microclimatic processes and trends.
- Climate model formulations need to be modified to recognise that parameters based on the behaviour of the atmosphere at low latitudes do not necessarily reflect processes operating in the Polar Regions, where the atmospheric boundary layer is commonly very stable. These models must include more sophisticated representation of the formation and melting of sea ice and its effects. In addition, the models need to be interactively coupled to ice shelf models so that the impact of changes in ocean circulation and water mass delivery below the shelf can be correctly simulated. This will lead to better predictions of sea level changes that might arise from interactions of the waters of the Southern Ocean with the periphery of the Antarctic Ice Sheet.
- Improved atmospheric chemistry needs to be included so that the models can better represent the effects of the ‘ozone hole’, including the important polar stratospheric clouds. Greater spatial and temporal resolution are also imperative if biological processes, particularly on land, are to be integrated into future generations of climate models, and to permit objective tests of predictions of biological relevance. Advanced integrative and spatially explicit ecosystem modelling is needed to predict the future of the marine ecosystem. Such an approach demands widespread samples of ecological key species that are representative for ecological sub-systems, such as plankton, benthos or apex predators and long-term measurements of ecological key processes such as the response to acidification, warming and changes in ice cover and food regime.
- Realistic models are urgently required of the mechanical behaviour of the ice sheet and ice shelves in response to forcing by climate change, to underpin forecasts of likely sea-level rise and of the rates of change of ice sheet decay. To achieve this the next generation of ice sheet models must be able to account for rapid dynamical changes to the flow of glaciers and ice streams.
- Modelling efforts are also required to more fully understand the implications of Antarctic and Southern Ocean climate change throughout the Southern Hemisphere and globally, and vice versa.
- More observations are needed of permafrost, along with model predictions of permafrost change. It is import to expand the Circum-Polar Active Layer Monitoring (South) (CALM-S) network. To improve understanding of the development and evolution of permafrost under changing conditions in the Antarctic there needs to be an expanded Global Terrestrial Network for Permafrost sites (GTN-P) in Antarctica.
- A central location should be established for management of Antarctic permafrost, active-layer, and ground ice data.
- The PERMAMODEL should be applied to predict changes in permafrost distribution under different climate change scenarios, particularly along the Antarctic Peninsula and in maritime East Antarctica.
- Continued long-term and large-scale observations of functional and structural changes in ecosystems are essential to assess the sensitivity of ecological key species and to ground-truth predictive models. The establishment of a series of core long-term biological monitoring sites would be extremely beneficial both in documenting biological responses and trends, and allowing explicit tests of predictive hypotheses.
- More data on the marine biota are required for especially poorly studied areas like the Amundsen Sea, as the basis for the simulation of the impact of a warming ocean on marine biodiversity.
- Physiological and genomic studies currently interpreted as indicating vulnerability of certain Antarctic marine biota need placing in more ecologically realistic (longer term) timescales.
- Individual and species level responses (including resilience/resistance) to environmental variability and change require integration across communities, trophic webs and ecosystems.
- Biological colonisation routes and processes require identification and quantification in both terrestrial and marine environments, as does the relative importance of natural and human-mediated contributions to this process.
- Without a baseline biodiversity survey across much of the continent and Southern Ocean, objective documentation of future biological change and assessment of impacts will be impossible.
- Evidence should be sought for the possible effects of ocean acidification in Southern Ocean organisms.
- Comparisons should be made between southern and northern polar processes to shed light on evolutionary pressures and provide insight into gene selection.
- Many of the above recommendations will benefit from continued integration of cross-disciplinary expertise and approaches.
- Considerable improvement is needed in both the quantification of changes in precipitation (requiring an intense field programme), and the parameterization of the processes that drive precipitation. In due course, especially in the Antarctic Peninsula, biologists need to know what proportion of the precipitation is likely to fall as rain, since rain is immediately available to terrestrial biota.
- A better understanding of ecological driving forces within Antarctic ecosystems (terrestrial and marine) must serve as the basis for developing predictive models of the response of the Antarctic biota to climate change.