Anthropogenic Forcing of the Climate System

Human activity, through industry, agriculture, energy generation and transportation, has released significant amounts of greenhouse gases into the atmosphere since the beginning of the industrial era that began in the first half of the 19th century. Today, there is concern that this may be inadvertently modifying the global climate through an enhancement of the natural greenhouse effect. According to the IPCC (2001), global mean temperatures could increase by 1.5 to 5.8°C by the end of the 21st century in response to the enhancement of radiative forcing in the atmosphere. While this may appear to be a minor amount of warming when compared to diurnal or seasonal amplitudes of the temperature cycle, it should be emphasized that the projected global-mean temperature rise is unprecedented in the last 10,000 years. It is not only the amplitude of change but also the rate of warming that is generating concern in the scientific community, especially in terms of the vulnerability and response of environmental and socioeconomic systems to climatic change.