Could the answer to controlling global climate change lie in the ocean? Carbon dioxide, the leading greenhouse gas, is naturally absorbed into the ocean, where it does not affect atmospheric temperatures. Now some scientists and entrepreneurs want to artificially augment that process to increase carbon dioxide absorption and control global warming. In one plan, CO2 generated by power plants would be converted to liquid form and pumped into the depths of the sea. In another, scientists would fertilize the surface of the ocean to cause an algae bloom; the algae would then absorb carbon dioxide and, as the bloom died, sink to the ocean floor, trapping the CO2. But critics caution that excess CO2 could harm deep-sea creatures and have unknown other effects on ocean ecology. Sallie Chisholm, a scientist at MIT, is one of the skeptics: “It’s like saying: ‘What’s so bad to adding carbon dioxide to the atmosphere? There’s already CO2 in the atmosphere.'”