The irrigated farming in the Murray Darling Basin in Australia, for example, accounts for around 40% Australia's total value of agricultural production, and two-thirds of Australia's total irrigated land and over 50% of national water withdrawals (Australian Bureau of Statistics, 2008). Globally average rainfall increased by about 2% over the period 1900 to 1998 (Huntington, 2006). But regional variations in rainfall are highly significant rising over this period, by 7-12% between 30°N-85°N, compared with a 2% increase for 0°S-55°S, but with substantial reductions in some regions.