"Now CO2 itself... doesn't really want to pick up any electrons and become reduced to an organic molecule, but if it's in a relatively ic environment where there's s available, it picks up a negative charge. It doesn't want another negative charge. It's going to try and repel that, but if there's a proton around, it picks up the proton. Now it's neutralized the charges... pick up another electron, another proton. So it's much easier to accept electrons in an acidic environment. And this is the structure of these vents and it's the structure of cells, and it's how these earliest, most ancient cells we know about actually do fix CO2. They use the proton channel in the , which effectively locally acidifies an environment and allows this reaction to proceed. So I think that's fundamental, simple... works well, and it's testable in the lab."