Australian+Climate

__**Australian Climate**__

Australia is the driest continent in the world and also home to some of the most unique species known to man. It has large varieties of landscape which are directly affected by the tropic of Capricorn's warm air currents. This causes the dry, sinking air of the subtropical high pressure belt which moves north and south with the el Nino and la Nina weather patterns. This causes the rainfall pattern over Australia to be strongly seasonal. Most of Australia's primary production occurs in the temperate regions of the south and east, and relies on winter rainfall. Cold snaps lead to frosts inland, though temperatures about the coast remain mild all year round. Summers over southern Australia are mostly dry and hot. Following a long dry spell, hot, dry winds from the interior can cause bushfires in southern and eastern Australia. The flammability of the Australian bush has adapted to the climate and many plant species even require these fires to reproduce. (bureau of meteorology, 2011).

The large interior portion of Australia is too dry to support freshwater ecosystems, leaving the coastal fringe condensed with majority of freshwater populations (Moll & Moll 2004; Pittock & Finlayson 2011). River flows are impacted upon by variable rain fall patterns and rising temperature (Dunlop, Brown & Australian Greenhouse Office 2008; Kingsford 2011; Michael //et. al//. 2010), with an overall trend of decreased flows, longer periods between floods and extreme flash flooding events (Pittock & Finlayson 2011). Temperature averages have risen by 0.7˚C over the past century (Dunlop, //et.al.// 2008), further contributing to water evaporation and drying of wetlands (Lough & Hobday 2011). Additionally, climate variables of rainfall and temperature appear to follow a decadal pattern, compounding the fluctuations observed in river systems (Lough & Hobday 2011). Prolonged drought periods including extreme rainfall patterns (Kingsford //et. al//. 2011) and variable climate pattern may provide a difficult climate for successful adaptation. In comparison, tropical regions of northern Australia experience a wet summer as the monsoon moves in. During the monsoon, moist north-westerly winds bring humid conditions with showers and thunderstorms. Rainfall amounts may vary markedly from season to season and occasional tropical cyclones can bring large amounts of rainfall to coastal regions and further inland. Once the monsoon has retreats, winter brings mild, dry conditions. Dry land agriculture and pastoralism have adapted to the harsh climate of the inland tropical area vastly due to selective breeding, artificial environment and in some cases, genetically modified crops. As a result of the influence of the high pressure belt, much of Australian rainfall is low and variable. Eighty per cent of the continent has an average annual rainfall less than 600 mm. The vegetation and animals of the dry interior adapt to dry conditions and respond quickly when rainfall is received. (bureau of meteorology, 2011)

Climate in eastern Australia is often determined by whether the southern oscillation index (SOI) is either positive, indicating La Nina climatic conditions or negative, indicating El Nino climate conditions. The SOI is a measure of the variation in air temperature difference between Darwin (Australia) and Tahiti (middle of Pacific Ocean) (Bridgman, H., //et al.//, 2008). Modern literature and SOI graph work targeted at Australian climatic research is adamant that the change in direction of the SOI is strongly correlated with temperature and climate changes on the eastern coast of Australia ( Bureau of Meteorology, 2011). Climate graphs and their descriptions indicate and conclude that many low negative SOI events were associated with lengthened episodes of drought (Appendix 2). A review of Troup J., 1965 points out that data from older periods in time may lack in consistency, and results are less obviously translated. Standardised methods have been introduced since the release of that article to create a more reliable and consistent data set. Data provided in ranges of climate related data is often region central and oceanic or air temperature variation is regularly variable (Bridgman, H., //et al.//, 2008).