A Scoping Study on Impact and Adaptation Strategies for Climate Change in Victoria A Working Paper produced as part of a three-year research program on: Assessment of climate change, impacts and possible adaptation strategies relevant to Victoria Undertaken for the Greenhouse Unit of the Victorian Department of Sustainability and Environment by the Climate Impact Group, CSIRO Atmospheric Research Authors: R.N. Jones and K.L. McInnes April 2004 Address for correspondence Dr Roger Jones CSIRO Atmospheric Research PMB No 1, Aspendale, Victoria 3195 Telephone (03) 9239 4555 FAX: (03) 9239 4444 E-mail: [email protected] ACKNOWLEDGMENTS The Victorian Department of Sustainability and Environment Greenhouse Unit organised the workshops. All the people who gave their time and attended are gratefully thanked. Those who presented and assisted at the workshops are Paul Holper, Janice Bathols, Bob Cechet, Kevin Hennessy, Mark Howden, Ian Mansergh, Cher Page, Ramasamy Suppiah, Kevin Walsh and Penny Whetton. This work was produced by CAR under contract to the Victorian Department of Sustainability and Environment. This work also contributes to CSIRO’s Climate Change Research Program. 2 Executive Summary This document is a working paper compiled by CSIRO to outline the first steps in developing an impact and adaptation assessment program for the Government of Victoria. Its role is twofold: 1. To describe methods being developed by CSIRO and international collaborators to carry out risk assessments of vulnerability to climate change and develop strategies for adaptation to climate change in Victoria, and 2. To describe the results of a series of workshops on catchments and water, agriculture, biodiversity and coasts held in May–June 2001. Key climatic variables Key climate variables were identified to distinguish the main drivers of change and climate hazards. This exercise demonstrated the importance of moisture, particularly rainfall and secondary variables derived from rainfall such as runoff and floods. Rainfall and its variability drive a large number of processes. For example, while extreme rainfall is likely to increase the magnitude of changes to annual mean rainfall are highly uncertain. Seasonal changes in rainfall indicate possible increases in summer– autumn and probable decreases in winter–spring, which could lead to an uneven seasonal distribution of increasing daily extreme rainfall. Temperature changes are less important but the magnitude of warming expected over the coming century poses significant risks. These findings from the four workshops will be used to guide the development of coping ranges that will be used to assess risk under a changing climate. Sectoral findings Water and catchments The recent CSIRO (2001a) climate projections and summary of impacts (CSIRO, 2001b) indicate that reductions in water supply are likely for Victoria. The adaptive capacity of water management to interannual climate variability (e.g. the El Niño – Southern Oscillation) is high, but the risks of longer- term, sustained reductions of water supply remain unknown. Climate change needs to be factored into ongoing water reform processes including market development, planning for water quality, river health and environmental flows. Possible interactions between climate change and salinity, including how they may influence salinity management options, is a key long term issue for catchment management. Agriculture The agricultural sector is generally well adapted to climate variability. The relationships between climate and performance criteria, such as crop yield and quality, are known for most agricultural activities. Increases in atmospheric carbon dioxide will increase plant productivity, which is likely to counterbalance the impacts of lowered available moisture, as long as temperature effects remain tolerable. Further work on how climate change may affect production systems will be needed to maximise agricultural performance under such conditions, particularly at higher temperatures. Adaptation will be required for longer-lived crops near the boundaries of their current climatic limits. The impact of agriculture on land systems at the catchment scale, the risks of long-term water supply to irrigated agriculture and the long-term threats of dryland salinity under climate change require further research. Biodiversity The relationships between biota and climate change are poorly known at the species level and largely unknown at the community level. The resilience of ecosystems to natural climate change is high if they are allowed time and space to respond. However, in a landscape where many systems are fragmented and subject to weed and pest invasion, ecosystems will be much more vulnerable. The 3 impacts of increased CO2 on ecosystem functions of natural communities and on species distribution is largely unknown. In order to develop options for planned adaptation, research needs include a better understanding of the dynamics between climate and biodiversity and processes of autonomous adaptation within the modern landscape. Fragmentation issues, and pests and weeds will need to be actively managed because the latter’s invasive potential will be enhanced by higher CO2, nutrient changes and increased ecosystem turnover. Coasts New IPCC (2001a) projections of sea-level rise are slightly lower than previous estimates, being 9–88 cm by 2100. The regional rate of risk remains unknown. Sea-level rise is also expected to rise for centuries after stabilisation of greenhouse gases, so emissions over the next century will contribute to long-term risks. The impacts of sea level rise will be felt through storms and related surge events, with mean sea level rise adding to their severity. Storm patterns may not change greatly, but may become slightly less frequent but slightly more intense. The most vulnerable coasts are those that are low-lying with very little setback to allow for adaptation. Estuarine processes under climate change are poorly understood. Natural estuarine systems are biologically very important, so setback strategies will be needed rather than hard barriers such as sea walls, but will be limited where prior development has occurred. Some areas of coast may be subsiding due to tectonic or other processes; low-lying sections of these coasts will be the most vulnerable. Integration needs The workshop results consistently showed that criteria that demonstrate the success or failure of an activity are driven by both climate and socio-economic influences. Risk is a combination of the degree of harm measured by given criteria, and how often it may occur. The decision as to which criteria can be used in an assessment are ideally jointly made by stakeholders and researchers and may be couched in both monetary and non-monetary terms. It is the researchers’ task to take this information and quantify relationships within an analytic framework. The assessment of risk is a joint exercise made by stakeholders guided by expert advice. The integration of biophysical and socio-economic drivers of change within the risk assessment framework shows that climate assessments cannot be considered in isolation but that they should be considered with the other major drivers of change. This is consistent with the idea of “sustainability science” where different drivers of change are integrated to develop a holistic approach to risk management. This suggests that adaptations to climate change will need to be part of a larger scale effort to implement sustainable development. The integration with other sectors was raised in each of the workshops. Links from agriculture and biodiversity to catchment management, of water to agriculture, of agriculture to biodiversity and of catchments to coasts emphasises the importance of cross-sectoral interactions. Due to the large uncertainties and complexities involved, it is not possible to simulate these interactions in a predictive way but also lacking are the tools to explore these interactions. DSE needs to develop capacity in this area, perhaps building wider relationships between the relevant research institutes but also in collaboration with other organisations such as CSIRO, CRCs and universities. Ongoing work Several projects are ongoing, including: Agriculture Development of an expert-based Geographical Information System for assessing change in agricultural activities. A scoping study for South Gippsland has been completed and a larger multi- year study is planned for 2003 onwards. 4 Hydrology Initial modelling has been undertaken for Ryan’s Creek in north central Victoria (Chapter 2) and a larger scoping study is being planned. Funds have been sought for a major collaborative study in the Goulburn-Broken catchment. The current drought has been the catalyst for discussion on longer term changes. Biodiversity A collaborative study between the Arthur Rylah Institute and CSIRO is ongoing, investigating the bioclimatic envelope of twenty plant species representing important vegetation communities. A workshop was held at Arthur Rylah Institute in June 2002. Coasts A coastal workshop for stakeholders was held by the Victorian Coastal Council in November 2002. Gippsland Coastal Board has a project planned to study sea-level change and coastal subsidence and their implications for the Gippsland coast. Alpine Environments Studies currently completing work on projected snow cover for the ski industry. Further work is looking at the impacts of reduced snow cover on alpine biota. This is co-funded by the Australian Greenhouse