Variations and correlations among climatic and environmental variables in Australia using GIS and remote sensing

Abstract: This study was performed because of the potential vulnerability to climate change of the Australian continent. For example, global warming may increase the frequency and severity of drought [McAlpine, C.A., Syktus, J., Ryan, J.G., Deo, R.C., McKeon, G.M., McGowan, H.A. & Phinn, S.R., 2009: A continent under stress: interactions, feedbacks and risks associated with impact of modified land cover on Australia’s climate. Global Change Biology 15, 2206-2223]. The aim of this study is therefore to investigate spatial and temporal patterns in temperature, rainfall, and solar radiation and how native vegetation (represented by NDVI) and land-use correlate with these climatic parameters. The correlations are investigated during the 1982-2006 period across the Australian continent. To meet this general aim, three objectives are implemented: (1) to identify how these variables vary spatially and temporally; (2) to investigate whether spatial variations in these variables correlate; (3) to investigate whether temporal variations in these variables correlate. Using GIS software, maps are produced that show how the selected parameters vary over the study period across the Australian continent. During winter there is a trend of increasing temperature, solar radiation, and vegetation density and spatial distribution during 1982-2006. It is likely that the climatic variation over the 1982-2006 period is forcing the observed change in winter vegetation. The systematic variations of the trend indicate that winter is the key season over the 1982-2006 study period. Decreased winter rainfall over 1982-2006 across all of Western Australia, along with a trend of increasing summer rainfall displayed over the same period, indicate a negative outcome for this part of the continent. This is because there is more water runoff to streams and soils in the winter, because of low evapotranspiration and cool temperatures. The strongest correlation between spatial variations in vegetation distribution and climatic parameters during winter seasons 1982-2006 occurs between vegetation and temperature. During summer seasons over the same period, the strongest correlation occurs between vegetation and solar radiation. Correlations between expansion of selected land-use areas and spatial variations in climate during 1992-2005 show ambiguous patterns and could possibly be random. These findings are also unreliable because the land-use data has some significant errors, e.g. in estimated agriculture areas. During 1982-2006, the strongest correlation between temporal variations in vegetation density-distribution and climatic parameters occurs in the summer vegetation-temperature relationship (mean R² = -0.53). Vegetation density displays over 1982-2006 negative correlations with temperature and solar radiation, and positive with rainfall. Relationships between temporal variations in climate and selected landuse areas over the 1992-2005 period indicate a specific pattern. Areas of water, conservation, and production from relatively natural environments show, in general, higher mean values in all climatic parameters (except for winter rainfall) than other land-use areas. Because these land-use areas are mainly distributed in hot and arid Australian climate zones, the climate is unsuitable for agriculture, which might explain their higher mean values in the climatic parameters than, for example, croplands. The findings of variations (trends) and correlations in the present study, together with previous predictions, indicate that the future for Australia might be challenging because of increasing frequency of droughts and forest fires. Therefore, the potential vulnerability to future climate change of the Australian continent is of great concern.