Climate change and carbon management in the Monsoonal North

[摘要] This report is provided as part of a study of the impacts of climate change on the Monsoonal North Natural Resource Management Region of Australia. It focusses on carbon sequestration and emissions abatement using the Carbon Farming Initiative’s savanna fire methodology in the context of fire management. It was originally intended that the latest results from climate change simulations would be used to parameterise a vegetation dynamics model to examine scenarios for future carbon stocks and the consequences for fire management. However the simulations were not available in time to conduct vegetation modelling and even if they had been available would not have been suitable due to a lack of sensitivity in the critical area of rainfall seasonality. Therefore, following discussions, it was agreed that we should provide a review of the drivers of carbon dynamics in the Monsoonal North in the context of the savanna fire methodology and apply models based on a number of possible rainfall scenarios. The savanna fire methodology presents default parameters to calculate the emissions abatement that is deemed to occur as a result of changing the fire regime in defined project areas. Although these climate change may cause the value of these parameters to alter in the future, they will remain as the default values until a revised or new methodology is produced. Consequently the main issue of concern for land managers is climatic factors affecting fire regimes. Climate change is likely to lead to more severe fire weather in the late dry season due to higher temperatures and lower humidities. However, during the early dry season, there will remain opportunities to burn landscapes with relatively benign, patchy low intensity fires. The savanna fire methodology is based on the use of such early dry season fires to reduce overall fire frequency and reduce fuel consumption and thereby emissions of methane and nitrous oxide. Although the window of opportunity may alter under climate change, we have no ability to predict that with current knowledge. We do know that it is variable presently. We conclude that the approach of using early fires will remain valid under likely climate change scenarios. For the monsoonal north, changes in rainfall seasonality are potentially of great significance, but these are difficult to predict using current knowledge. Australia generally has highly variable rainfall but there is evidence of increasing dry season length in North Queensland and decreasing length in the south Kimberley region of Western Australia. We have good evidence that length of the dry and wet seasons rather than the amount of rainfall per se is the main factor affecting tree stocks and therefor carbon stocks in the landscape. Unfortunately current climate models do not have a robust ability to model robustly the isolated storm events that determine the transitions between the dry and wet seasons. Therefore we produced a range of scenarios of possible changes in seasonality and modelled their effects of vegetation and carbon stocks. Increasing the length of the dry season could have a marked impact on vegetative carbon stocks. This would be greatest if this occurred in the Charters Towers region of Queensland, which currently has the greatest likelihood of winter rainfall across the Monsoonal North. Such changes would alter the tree-grass balance and thus the makeup and amount of the fuel for savanna fires. IF it could be demonstrated that such changes were permanent, then future versions of the savanna fire methodology would need to be reparametrized

[发布日期] 2015-09-21 [发布机构] CSIRO

[学科分类] 地球科学(综合)