Limited Predictability and the Greenhouse Effect – A Scientific Review

The concept of limited predictability is reviewed followed by simple examples illustrating the sensitivity to small changes in the initial state and/or the forcing of a non-linear system. Limited predictability applies to almost all non-linear systems, and the concept is therefore important to geophysical systems governed by non-linear model equations. The limited predictability determines the upper limit to operational weather forecasts, but it will also be demonstrated that it has an impact on the determination of the effect of changes in the forcing of the system. The general strategy applied by researchers to estimate the atmospheric greenhouse effect is reviewed. It will be demonstrated that the adopted strategy, due to prescribed changes in the forcing of the climate system, is also influenced by limited predictability in the sense that predicted changes are much larger than observed changes in the temperatures at the surface of the Earth. It is therefore very unlikely that the predictions are reliable. The inclusion of the sulphur-aerosol effects are also discussed with the conclusion that although these cooling agents reduce the greenhouse warming, they do not behave as expected in the sulphur-rich and sulphur-poor regions.