ABSTRACT

Critics of this viewpoint suggest that the predictions made may be over-estimated due to a misrepresentation of basic atmospheric feedback mechanisms (e.g. Lindzen, 1994, 1997; Pearce, 1997), that mechanisms of cooling have been missed (Hansen et al., 1997) or simply that there is little evidence to support the case from instrumental records (e.g. Michaels et al., 1998). On the other hand, rates of change may be too small to be noticeable against background noise (Hansen et al., 1998). Hansen et al. (2000) also suggest that rates of forcing in the twenty-first century may also slow due to the reduction of non-CO2 greenhouse gas emissions.