Australia. Rivers die from the mouth up. And in South Australia, the Coorong - at the head of the Murray-Darling Basin - is doing just that. The unique salty wetlands (once home to hundreds of thousands of wading birds) are in sharp decline. Water-intensive farming practices upstream have done untold damage to the Basin over the last 40 years, yet now it is a recent government intervention that is most to blame for imminent disaster. Australia's Murray-Darling Basin Plan is a $9b initiative that was conceived to return water to the Basin; but what has been pumped in instead is nutrient-rich farming run-off that has upset the
delicate saline balance of the wetland. The resulting algal blooms are decimating the plant, insect and bird populations and hastening what local scientists believe to be a collapse of the entire system.
New Zealand. A country that is renowned for its pristine natural beauty, New Zealand is in the midst of its own reckoning with plummeting water quality. Two years ago the health of lowland rivers was brought into sharp focus after 5,000 people fell ill because an aquifer had become contaminated with bacteria from sheep faeces. As in Australia, environmental concerns here too have
played second fiddle to the financial imperative of strong primary industries.
India. The Australian example showed how damage wrought by the depletion of natural resources can be exacerbated by politically-negotiated interventions that continue to favour polluters. But sometimes an intervention may not even happen at all. The Narmada river running through India was once fed by seven tributaries. Today it has
been reduced to just one. Excess damming has created a complicated and protracted argument between neighbouring states over extraction rights. Yet while governments bicker the Narmada continues to carry less water with each passing year, and what it does bring downstream is now filled with silt, pollution and minerals.
America. A recent study has shown that nearly every major river system in the United States
is becoming more alkaline. Salinity is rising in the southern rivers due to exposure to limestone from human activity, and also to salt-heavy fertilisers and pollutants. It's a lesson being learned (or rather, NOT being learned) all over the world: what goes into the river is just as damaging as what and how much is taken out of it.
The expansion of agriculture worldwide doesn't just lay claim to ever-greater amounts of fresh water and pollute whats left; it also leads to the destruction of biodiversity. The definitive study of global bird populations released this week, the State of the World's Birds, shows that one in eight bird species is threatened with extinction. Moreover, a staggering 74% of the 1,469 species are
at risk due to farming. One contributor to the survey noted that the world might be able to feed itself and also leave room for the birds if sustainable farming practices were uniformly adopted, and if food waste could be reduced. The latter sentiment was also validated by another study this week which found that
Americans throw out 150,000 tonnes of food each and every day.
Last but not least, any discussion about water pollution wouldn't be complete without touching on the pervasive threat of microplastics filtering through our ecosystem.
One particularly galling story this week described micro-plastics that have been found in ocean-floor sediments 2km below the surface of Australia's most isolated and pristine ecosystems, the Great Australian Bight. Not to be outdone, the most remote stretches of North America's Great Lakes region too were found to be heavily populated with plastics.
Looming behind the water crisis is the larger spectre of climate change. While some positive news surfaced this week (Michael Bloomberg wrote a $4.5m cheque to help
make up the shortfall of America's broken commitment to the Paris Climate agreement) most of it has been grim. This week the early stages of an oceanographical study were released; they seem to confirm one of the most dangerous modelled trends about climate change. As Antartica's ice sheets melt it is diluting the salty sea water around it. This is short-circuiting an ocean current cycle that sees dense, cold, salty water sink below the ice sheets in winter. However, the fresh water is allowing warmer currents from elsewhere on the planet to flow under the ice shelves, thus hastening the melting process.
It's a negative feedback loop that we've just begun to understand the effects of: rising sea levels and super storms.
