Indeed, most climate scientists now suspect that the accumulation of these gases in the lower atmosphere has contributed to the strong recent uptrend in world average temperature. In its Third Assessment Report, published in 2001, the Intergovernmental Panel on Climate Change (IPCC) stated: “There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities” (3). During the twentieth century, world average surface temperature increased by approximately °C (Figure ). There were, of course, natural influences on world climate during this time. These include an increase in volcanic activity between 1960 and 1991 (when Mount Pinatubo erupted) which induced.
