Figure 2: The global mean radiative forcing (Watts per square meter, W m-2) of the climate system for the year 2000, relative to 1750. The International Panel on Climate Change (IPCC) has applied a “level of scientific understanding” (LOSU) index is accorded to each forcing (See Table 2). This represents the Panel’s subjective judgment about the reliability of the forcing estimate, involving factors such as the assumptions necessary to evaluate the forcing, the degree of knowledge of the physical/chemical mechanisms determining the forcing, and the uncertainties surrounding the quantitative estimate of the forcing. Based on [57]