Impact of land cover change on regional climate and El Nino in Australia

• Main Authors: Syktus, J., Deo, R. C., McAlpine, C. A., McGowan, H. A., Phinn, S.
• Format: Conference Object
• Language: unknown
• Published: Modelling and Simulation Society of Australia and New Zealand 2007
• Subjects: land cover change; El Niño; droughts; climate impacts; Queensland; Sea ice
• Online Access: https://research.usq.edu.au/item/9zqy5/impact-of-land-cover-change-on-regional-climate-and-el-nino-in-australia; https://research.usq.edu.au/download/fc084ced663a6b9f6070e7936bb6ff087a4db47b8b87dce689ec75add261c67a/689500/Syktus_Deo_McAlpine_McGowan_Phinn_MODSIM07_2007_PV.pdf; https://research.usq.edu.au/download/71ad23a078633b43d0cdd94db55597ace1082b793df20513e7fa3c6aab45076c/61131/Binder1.pdf

Climate impacts of land cover change (LCC) are still a subject of discussion despite growing evidence that LCC affects global and regional climates (Zhao et al. 2001; Timbal and Arblaster 2006; Pielke et al. 2002; Narisma and Pitman 2003). To investigate the climate impacts of LCC, this paper presents results for two sets of 10 member ensemble experiments using CSIRO atmospheric GCM. The CSIRO climate model is a fully coupled atmosphere, land surface, sea ice and ocean model, with a model horizontal resolution of ~1.8o grid increment and 18 vertical levels. In this study, we used the uncoupled version where ocean and sea ice components were represented by observed seasonally varying sea surface temperatures and sea ice data. We quantified changes in land surface parameters and impacts on mean climate from the pre-European (1788) to modern day (1990) land covers and impact of ENSO on the strength of surface temperature anomalies during second half of 20th century. Preclearing land surface parameters were generated by extrapolating modern-day values of remnant native vegetation to the pre-European extents of each land cover class. The extrapolation was performed for Australian continent at 8 km spatial resolution and the fine scale parameters then aggregated using Shuttleworth’s (1991) approach to coarse resolution aggregated for model. The largest differences between pre- European and modern day surface parameters were in eastern Queensland, southwest Western Australia, and New South Wales/Victoria. In eastern Queensland, vegetation fraction and leaf area index during the summer decreased by 14% and 20% respectively. This corresponded to a surface albedo increase of 4%. Stomatal resistance increased by 3% and surface roughness decreased by 54%. In New South Wales/Victoria, similarly large decreases in vegetation fraction (19%) and LAI (23%) caused an albedo increase of 7%, while there was a corresponding 46% reduction in surface roughness. In southwest Western Australia, replacement of native woodlands with ...