BURYING crop waste deep in the ocean could be an effective way to rein in global warming.
The stalks and leaves left in fields across the world each year after harvesting contain a whopping 2 billion tonnes of carbon. Untouched, they decay and release carbon dioxide.
One solution could be to drop the waste into the deep ocean. Up to 30 per cent of the leaves and stalks left in fields after harvesting can be removed without damaging soil fertility, say in Seattle and . Sinking it could cut the annual rate of CO2 build-up in the atmosphere by 14 per cent, they say (Environmental Science and Technology, ).
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When it comes to places to bury CO2, oceans are high on the list. While forests can also mop up CO2, trees release the gas when they burn or die. Carbon sunk in the deep ocean, however, will stay there for thousands of years.
The method would cost about $95 per tonne of CO2, which is likely to be competitive with other methods, such as siphoning off CO2 from power stations and storing it in empty aquifers, says in California.