Dangerous danger

An editorial in Nature says:

Carbon sequestration is the only credible option that would allow the continued use of fossil energy without the threat of dangerously altering Earth's climate system. Speeding up its deployment must therefore become a priority on the global energy agenda.

The editorial does not explain what "dangerous" means in this context. So the conclusion that "deployment must therefore become a priority" does not follow. Deployment would be a priority only if its costs were less than the benefits of postponing climate change. In an accompanying news report Jon Gibbins states that the costs of sequestration from power plants are "trifles" and Robert Socolow does some amusing number crunching and estimates that they would result in a 20% increase in the electricity bill for consumers. Add grains of salt according to taste.