These scenarios are based on the "The Business-as-Usual" assumption that is not 100% valid. In IPCC 1990 business-as-usual scenario C02 emissions are roughly 45

These scenarios are based on the "The Business-as-Usual" assumption that is not 100% valid. In IPCC 1990 business-as-usual scenario C02 emissions are roughly 45 Gt today, in reality, it's 37 Gt. Probably the most important factor is that coal use has not increased to the levels predicted, because actions have been taken in the last decade or so.