Government officials estimate that dryland salinity resulting from land clearing is now threatening an area of land about half the size of the entire Australian state of Victoria—and in turn, the farming and ranching that is the underpinning of the national economy. In the words of a country song popular in the outback during the mid-1980s: “Stock won’t graze on pastures turned to salt.”

“We can’t afford to let the situation get any worse,” Murray River farmer Graham Winter recently told a TV audience. “We are on a knife edge. This is just a disaster.”

Added stockman David Clarke, “We are growing more salt than wool.”

A SALTY SURPRISE

The disaster began almost two centuries ago when the British ended their primary use of the island as a penal settlement, and colonists began arriving in large numbers. They sought to recreate the English countryside in this vast, rugged land, complete with farms.

But the clearing of millions of acres (hectares) of forests to make room for crops had an unintended consequence. Large areas of land in Australia contain shallow layers of salt. Just beneath them lie shallow aquifers. With thirsty trees no longer available to siphon it off, the water rose to the surface—bringing the salt with it.

The damage has been massive. About 10 percent of the wheat belt in Western Australia—about 4.5 million acres (1.8 million hectares)—has been salted, along with about 1.75 million acres (710,000 hectares) in southern and eastern Australia. Costs are estimated at AUS $130 million annually in lost agricultural production, AUS $100 million in infrastructure damage, and AUS $40 million in lost environmental assets.

Evidently the worst is not over. Scientists estimate that up to 30.9 million acres (12.5 million hectares), including some of the country’s most productive land, will be gripped by dryland salinity. In the Murray-Darling Basin alone—Australia’s most important agricultural production region—an estimated 7.4 to 12.4 million acres (3 to 5 million hectares) are likely to be affected.

The infusion of salt also threatens drinking water supplies in cities. Diversions of water by cities and for irrigation, along with evaporation, have reduced the flow at the mouth of the Murray River south of Adelaide to a trickle.

LAND CLEARING CONTINUES

Despite abundant evidence of its harmful effects, land clearing continues at a brisk pace in some areas of the country. The state of Queensland is stripping vegetation at a rate of more than 741,300 acres (300,000 hectares) a year—about 40 percent of it in the Murray-Darling Basin.

“This is clearly not sustainable land use,” says Australian Environment and Heritage Minister Robert Hill. “It poses severe threats to endangered ecological communities and animal species, it has major consequences for our efforts to reduce greenhouse gas emissions, and it is an open invitation to the ravages of salinity…. It defies the logic we supposedly had learned from the mistakes in other parts of Australia.”

Hill blames the continued land clearing in Queensland on a lack of leadership from the state government. Every other state on the mainland has introduced controls.

The willful refusal of Queensland leaders to restrict land-clearing is strenuously criticized by the country’s vigorous environmental movement. Among the most strident activists are those who live in the forests and blockade roads or set up platforms in trees to protect them from logging. Subsisting on donations and social security checks, they are referred to by other Australians as “ferals”—for the country’s abundant supply of domestic cats that have gone wild.

In a less radical and longer-term attempt to address the salinity problem, some farmers have organized voluntary efforts to bring native vegetation back to cleared lands by replanting.

Environment Minister Hill recently declared that dryland salinity is a result of one of the “mistakes we have made in the past in how we managed our natural resource base.” Many of these, he said, “date back to the time of settlement, when we believed we could simply import European-style farming practices to an ancient and fragile continent, far different from the European environment. Only now are we beginning to understand the full consequences.”

Eye in the Sky is a weekly series that brings you the story behind the headlines using satellite imagery, remote sensing, aerial photography, and maps. This feature is developed by National Geographic News with the sponsorship of the National Imagery and Mapping Agency (NIMA) and Earth-Info. Check out maps and imagery at http://www.earth-info.org.