Published scenarios of carbon emissions vary over a 40:1 range, and vary greatly even when the possible effects of future climate change policies are ignored. Differences in assumptions about how social and economic policies will affect the rates of economic growth throughout the world, population growth, international trade and investment, the rate of improvement in energy efficiency, and innovations and developments in non-carbon technologies are among the main reasons for such huge differences - alongside the considerable uncertainties that remain about the structural forms and parameters of the economic models used for making projections. The following analysis shows that a low carbon emissions scenario is fully consistent with developing countries achieving economic prosperity and the rich countries increasing theirs. It would depend on the emergence of non-carbon options, such as renewable energy, and this is indeed more likely to happen with favourable conditions for economic growth and innovation.