New Zealand Herald: Irrigated by one of the world’s mightiest river systems, the Murray-Darling Basin yields almost half of Australia’s fresh produce. But the basin is ailing and scientists fear that as climate change grips the driest inhabited continent its main food bowl could become a global warming ground zero. The signs are ominous. In the Riverland, one of the nation’s major horticulture areas, dying vines and parched lemon trees attest to critical water shortages. Farmers have had their …