Changes in future greenhouse gas emission levels are highly uncertain, and a wide range of quantitative emission projections have been produced. Rogner "et al." (2007) assessed these projections. Some of these projections aggregate anthropogenic emissions into a single figure as a "carbon dioxide equivalent" (-eq). By 2030, baseline scenarios projected an increase in greenhouse emissions (the F-gases, nitrous oxide, methane, and , measured in -eq) of between 25% and 90%, relative to the 2000 level. For only, two-thirds to three-quarters of the increase in emissions was projected to come from developing countries, although the average per capita emissions in developing country regions were projected to remain substantially lower than those in developed country regions.