In dynastic China, one of the signs that a dynasty had lost the mandate of Heaven was widespread flooding. At one level, flooding can be taken to mean that heaven is turning its face from the dynasty. At another, it meant the dynasty had lost the administrative clout to manage the extensive system of dikes and canals that kept China's rivers in check. Like a lot of things in dynastic China the flooding theory worked. Naturally a failing dynasty would go to great lengths to assail the reports of hydraulic disasters because even failing dynasties prefer to postpone the inevitable if they can.
Paul Krugman writes today:
When archaeologists excavated the cities of ancient Mesopotamia, they were amazed not just by what they found but by where they found it: in the middle of an unpopulated desert. In "Ur of the Chaldees," Leonard Woolley asked: "Why, if Ur was an empire's capital, if Sumer was once a vast granary, has the population dwindled to nothing, the very soil lost its virtue?"
The answer � the reason "the very soil lost its virtue" � is that heavy irrigation in a hot, dry climate leads to a gradual accumulation of salt in the soil. Rising salinity first forced the Sumerians to switch from wheat to barley, which can tolerate more salt; by about 1800 B.C. even barley could no longer be grown in southern Iraq, and Sumerian civilization collapsed. Later "salinity crises" took place further north. In the 19th century, when Europeans began to visit Iraq, it probably had a population less than a tenth the size of the one in the age of Gilgamesh.
Salination is a major problem in Australia.
Approximately 5.7 million hectares of Australia's agricultural and pastoral zone have a high potential for developing dryland salinity through shallow watertables. Predictions based on groundwater trends, field surveys and landscape characteristics indicate that unless effective solutions are implemented, the area could increase to 17 million hectares by 2050 (Table 1, Figure 1). Most is agricultural land (more than 11�million�hectares).
We face the prospect of river collapse in the Murray-Darling Basin. The MDB ministerial council is considering three options in November for restoring environmental flows to the basin's rivers. Restoring 1500 gl to the rivers, the most radical option the council will consider has only moderate chances of ensuring living rivers. The basin holds % of all Australia's croplands.
Ozplogistan is just now suffering one of its periodic convulsions over global warming. I am not a scientist so I will not try and contribute to argument over science beyond noting, as Krugman does, that 'Very few independent experts now dispute that manmade global warming is happening'. Gummo Trostsy has done an excellent appreciation of the Veizer/Shaviv theory. I can comment on the politics and I think it's instructive to look at the public policy being pursued on salination, the Murray-Darling and global warming.
In all three cases, the official solution is to question the science and adopt half-measures which do not meet the crisis.
When a dynasty failed in traditional China the ecological effects did not reach beyond the empire's borders and eventually a new dynasty rebuilt the dikes. It is doubtful the Earth can be restored if global warming is real and our global civilisation takes no action to reduce greenhouse emissions. The science of global warming is close to certain. The risk of ignoring global warming, like the risk of ignoring salination or the Murray-Darling, is unthinkable. The widespread northern hemisphere drought and heat wave has already called almost 2000 people, dozens in Europe and hundreds in India. The numbers will soon exceed 911. Why is this crisis so much less urgent than the War on Terror?