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The Australian Government is meeting the challenge of water scarcity and climate change through significant on-farm infrastructure investment to increase water use efficiency and productivity, and secure longer term water supplies. However, it is likely that on-farm infrastructure investment will alter energy consumption and therefore generate considerable greenhouse gas (GHG) emissions, suggesting potential conflicts in terms of mitigation and adaptation policies. In particular, the introduction of a price on carbon may influence the extent to which new irrigation technologies are adopted. This study evaluated trade-offs between water savings, GHG emissions and economic gain associated with the conversion of a sprinkler (hand shift) irrigation system to a drip (trickle) irrigation system for a lettuce production system in the Lockyer Valley, one of the major vegetable producing regions in Australia. Surprisingly, instead of trade-offs, this study found positive synergies – a win–win situation. The conversion of the old hand-shift sprinkler irrigation system to a drip irrigation system resulted in significant water savings of almost 2 ML/ha, as well as an overall reduction in GHG emissions. Economic modelling, at a carbon price of $ 30/t CO2e, indicated that there was a net benefit of adoption of the drip irrigation system of about $ 4620/ML/year. We suggest priority should be given, in the implementation of on-farm infrastructure investment policy, to replacing older inefficient and energy-intensive sprinkler irrigation systems such as hand shift and roll-line. The findings of the study support the use of an integrated approach to avoid possible conflicts in designing national climate change mitigation and adaptation policies, both of which are being developed in Australia. [Copyright &y& Elsevier]

• We assess the potential inclusion of blue carbon within Australia's Emissions Reduction Fund, emphasizing issues and approaches that have global relevance. • We identify twelve potential management actions then quantify and discuss the five most promising activities, encompassing the protection, restoration and creation of mangroves, tidal marshes and seagrasses. • On a per area basis, mean abatement intensity of organic carbon was highest for the management activity ' (re)introduction of tidal flow' which may result in mean annual abatement of 13 – 15 Mg C org ha−1 yr−1 for mangrove and 6 – 8 Mg C org ha−1 yr−1 for tidal marsh. • Our approach offers a template that uses best available information to identify options for carbon abatement through management of coastal landscapes. There is increasing interest in protecting, restoring and creating 'blue carbon' ecosystems (BCE; mangroves, tidal marshes and seagrasses) to sequester atmospheric CO 2 -C and thereby contribute to climate change mitigation. While a growing number of countries aspire to report greenhouse gas emission and carbon sequestration changes from these ecosystems under voluntary international reporting requirements, few countries have domestic policy frameworks that specifically support the quantification and financing of carbon emission abatement through BCE management. Australia, as home to approximately 5–11% of global blue carbon stocks, has a substantial interest in the development of blue carbon policy. Here we assess the potential inclusion of blue carbon within Australia's Emissions Reduction Fund, emphasizing issues and approaches that have global relevance. We used a participatory workshop of scientific experts and carbon industry stakeholders to identify blue carbon management actions that would meet the requirements of the Fund. In total, twelve actions were assessed for their greenhouse gas emission abatement potential and the ability to measure abatement reliably, using a combination of available data and qualitative and quantitative methods, including expert knowledge. We identify and discuss the five most relevant and promising activities, encompassing the protection, restoration and creation of mangroves, tidal marshes and seagrasses. On a per area basis, mean abatement intensity of organic carbon (C org) was highest for the (re)introduction of tidal flow resulting in establishment of mangrove (13–15 Mg C org ha−1 yr−1) and tidal marsh (6–8 Mg C org ha−1 yr−1), followed by land use planning for sea-level rise for the creation of new mangrove habitat (8 Mg C org ha−1 yr−1). The avoided disturbance of existing mangroves, tidal marshes and seagrasses has the twofold benefit of avoiding remineralisation of existing stocks, plus the future annual abatement associated with the net sequestration of atmospheric CO 2 -C as C org with the continued functioning of these BCE. Our approach offers a template that uses best available information to identify options for carbon abatement through management of coastal landscapes, and details current knowledge gaps and important technical aspects that need to be considered for implementation in carbon crediting schemes. [ABSTRACT FROM AUTHOR]

Policies aiming to preserve vegetated coastal ecosystems (VCE; tidal marshes, mangroves and seagrasses) to mitigate greenhouse gas emissions require national assessments of blue carbon resources. Here, we present organic carbon (C) storage in VCE across Australian climate regions and estimate potential annual CO2 emission benefits of VCE conservation and restoration. Australia contributes 5–11% of the C stored in VCE globally (70–185 Tg C in aboveground biomass, and 1,055–1,540 Tg C in the upper 1 m of soils). Potential CO2 emissions from current VCE losses are estimated at 2.1–3.1 Tg CO2-e yr-1, increasing annual CO2 emissions from land use change in Australia by 12–21%. This assessment, the most comprehensive for any nation to-date, demonstrates the potential of conservation and restoration of VCE to underpin national policy development for reducing greenhouse gas emissions. Policies aiming to preserve vegetated coastal ecosystems (VCE) to mitigate greenhouse gas emissions require national assessments of blue carbon resources. Here the authors assessed organic carbon storage in VCE across Australian and the potential annual CO2 emission benefits of VCE conservation and find that Australia contributes substantially the carbon stored in VCE globally. [ABSTRACT FROM AUTHOR]