Reducing emissions of greenhouse gases, mainly carbon dioxide, is a crucial task. Current measures include using technology to improve energy efficiency, planting forests to store carbon and promoting nutrient recycling so that carbon can be used to enrich the soil. The first two techniques are far more costly than nutrient recycling.

Forests that today soak up a quarter of carbon pollution spewed into the atmosphere could soon become a net source of CO2 if Earth

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In an ambitious proposal to counter global warming, an upstart power developer wants to build a coal-fired electric plant on the outskirts of New York City that would capture its emissions of carbon dioxide and pump the pollutant 70 miles offshore. The gas would be injected into sandstone a mile beneath the ocean floor in the hope that it would stay there for eons.