One way to keep carbon dioxide out of the atmosphere is to put it back in the ground. In the first
of two News Features on carbon sequestration, Quirin Schiermeier asked when the world's coal-fired power plants will start storing away their carbon. In the second, Emma Marris joins the enthusiasts who think that enriching Earth's soils with charcoal can help avert global warming, reduce the need for fertilizers, and greatly increase the size of turnips.
In 1879, the explorer Herbert Smith regaled the readers of Scribner's Monthly
with tales of the Amazon, covering everything from the tastiness of tapirs to the extraordinary fecundity of the sugar plantations. "The cane-field itself," he wrote of one rum-making operation, "is a splendid sight; the stalks ten feet high in many places, and as big as one's wrist." The secret, he went on, was "the rich terra preta
, 'black land', the best on the Amazons. It is a fine, dark loam, a foot, and often two feet thick."
Last month, the heirs to Smith's enthusiasm met in a hotel room in Philadelphia, Pennsylvania, during the World Congress of Soil Science. Their agenda was to take terra preta from the annals of history and the backwaters of the Amazon into the twenty-first century world of carbon sequestration and biofuels.
They want to follow what the green revolution did for the developing world's plants with a black revolution for the world's soils. They are aware that this is a tough sell, not least because hardly anyone outside the room has heard of their product. But that does not dissuade them: more than one eye in the room had a distinctly evangelical gleam.