In recent decades the number of these aquatic black spots has risen steadily. At the latest count there were 479 such sites, distributed along the most populous coastlines of Europe, Asia, the Americas and even Australia. Together they cover an area somewhat larger than Victoria, Australia.
The cause of Dead Zones is well understood: they are driven by the avalanche of nutrients which humanity dumps in the oceans – from agriculture, sewage, leaky landfills, urban stormwater, soil erosion, industrial and vehicle emissions. This rich nutrient soup provides the food source for vast blooms of algae – and as these die off they sink to the sea floor and decompose causing blooms of bacteria which strip the essential oxygen from the water column, often resulting in fish kills – their most visible impact.
The biggest contributors of all are the 110 million tonnes of nitrogen, 9 million tonnes of phosphorus and other nutrients which we unleash into the planetary ecosystem every year as we try to feed ourselves. That is off-the-scale compared with what the pre-human Earth circulated naturally.
- Excerpted from the article, March of the Dead Zones.
What we need is more robust recycling, but also a dwindling population, which could be facilitated by the global institutionalization of human rights for women.