Once written off as sci-fi fantasy, geoengineering now looks like the last best hope to avert harmful climate change. (Editorial)

Industrial-scale attempts to capture CO2 from coal-burning power plants or oil refineries and lock it away deep underground are getting an unprecedented boost from the U.S. government's $787 billion stimulus package.

The collapse of the Soviet Union had diverse consequences, not least the abandonment of crop cultivation in many areas. One result has been the vast accumulation of soil organic carbon in the areas affected.

As more and more multibillion-dollar projects for sequestering carbon dioxide (CO2) deep within the Earth seek financial support, human-formed fertile black soils in the Amazon basin suggest a cheaper, lower-tech route toward the same destination.

The addition of iron to high-nutrient, low-chlorophyll regions induces phytoplankton blooms that take up carbon. Carbon export from the surface layer and, in particular, the ability of the ocean and sediments to sequester carbon for many years remains, however, poorly quantified3.

Study casts doubt on iron-induced carbon sequestration.