Climate change in the Asia Pacific Region

Multiple factors indicate that the Asia/Pacific region possess a high degree of vulnerability to climate changes. Many nations within the region already struggle to cope with the current climate variability to which they are exposed including tropical cyclones, rainfall extremes, frequent droughts, and extreme tides. A review of 186 different regional and national estimates of the potential impacts of future climate change to various sectors within the Asia/Pacific region confirms that there is little room for optimism

Climatic background to past and future floods in Australia

Rainfall variability in Australia is generally among the highest in the world, largely due to the dominant influence of the El Nin˜o–Southern Oscillation. Australian climate has been characterized by wet and dry periods with sometimes sudden transitions from one mode to the other. Synoptic explanations and teleconnections are discussed, with an emphasis on the Murray–Darling Basin (MDB). Floods in Australia are generally of two types: local ‘‘flash floods’’ and widespread basin flooding. The latter often start in the upper reaches of the MDB due to tropical low‐pressure systems, and slowly move downstream. Floods in smaller subcatchments can be rapid and intense due to heavy thunderstorms or other instability exacerbated by topography. Global warming due to human activities is occurring. Observed rainfall trends may be partly natural but partly of human origin. Possible changes to rain‐bearing systems associated with tropical and midlatitude systems will be discussed, along with land cover change and possible effects on runoff, erosion, and sediment loading. The general picture for the MDB, despite significant uncertainties, is that the frequency of small catchment flash flooding is likely to increase, especially in autumn and winter and in summer over the northern and southern (but not central) areas of the MDB. Large catchment floods may increase in magnitude in summer in the northern parts of the Basin, but are less likely to do so in the south, where average rainfall is likely to decrease. Increased fire risk and decreased ground cover may lead to greater sediment loading and erosion during floods, although reforestation could slow runoff and decrease magnitudes of floods, especially in the upper catchments

Simulated and projected summer rainfall in tropical Australia: links to atmospheric circulation using the CSIRO-Mk3.6 climate model

Simulations of mean climate characteristics and atmospheric circulation patterns in the tropical region of Australia during the austral summer (December to February) are assessed by comparing against observations. An examination of the observed climatologies of mean sea level pressure, winds at lower and upper levels and rainfall with simulated climatologies show that the model captures the spatial structures of observed patterns fairly well. However, there are some discrepancies in the magnitudes between observed and modelled parameters. The model can reasonably reproduce the observed link between tropical Australian rainfall variability and the atmospheric circulation patterns. Changes in circulation patterns and rainfall are investigated for Representative Concentration Pathways (RCPs) 4.5 and 8.5. Spatial patterns of changes in circulation parameters and rainfall are very similar for both RCP 4.5 and RCP 8.5, but the magnitudes are larger for the RCP 8.5. Under anthropogenic climate change conditions, the CSIRO-Mk3.6 climate model simulates an atmospheric circulation pattern reflecting weaker monsoon conditions in the Australian region, and hence, reduced rainfall over tropical Australia. A slightly increased pressure over northwest Australia and slightly decreased pressure over north Asia is simulated. Winds at lower and upper tropospheric levels indicate opposing anomalies and reduced rainfall over a broader region that encompasses northern Australia, parts of Indonesia and around the Philippines. However, an increase in rainfall is simulated for the region east of Papua New Guinea

The CSIRO-Mk3.6.0 Atmosphere-Ocean GCM: Participation in CMIP5 and data publication

The participation of the CSIRO-Mk3.6.0 Atmosphere Ocean Global Climate Model (AOGCM) in the Coupled Model Intercomparison Project Phase 5 (CMIP5) is a joint initiative between the Queensland Climate Change Centre of Excellence and the Commonwealth Scientific and Industrial Research Organisation (CSIRO). It now has approximately 10 research and support scientists working on this project which first began in 2009. This on-going project consists of the following four main components:• A model design and testing period to ensure that the model had acceptable configuration for participation in CMIP5, in particular, exhibiting a realistic present-day climate and a stable preindustrial climate;• A model integration phase where CMIP5 experiments were performed. These were to include the so-called "core" experiments plus a number of "tier1" and "tier2" experiments, which will constitute a significant submission to CMIP5 and to address local climate modelling needs and applications;• Post-processing of the raw CSIRO-Mk3.6.0 model output into internationally recognised and standardized CMIP5 form; and • Quality control and publication phase of the CSIRO-Mk3.6.0 data to ensure entry into the Earth System Grid (ESG) Federation, allowing it to be disseminated to the CMIP5 international community. In this paper the four phases of this climate modelling project will be discussed in detail. The main emphasis is to make potentially interested researchers aware of the CSIRO-Mk3.6.0 climate model submission and to elucidate the range and features of the datasets that are now available. The CMIP5 datasets are being hosted on the ESG which consists of international data nodes and gateways, including Australia's own node hosted by the National Computing Infrastructure (NCI) National Facility in Canberra. A key outcome of our efforts is the generation of over 150, mostly high priority, uniquely defined parameters from the list of requested model output to understand climate processes and also produce new climate change projection data for impact assessment. Some preliminary results of the CSIRO-Mk3.6.0 model are presented to illustrate the usefulness of this dataset in this research area