Vital Climate Graphics : Potential Impacts of Climate Change
Next: Projected Changes in Global Temperature

20. Projected anthropogenic CO₂ emissions from fossil fuel use, deforestation and cement production are shown for some of the IPCC emission scenarios. The highest emission scenario - IS92e - assumes moderate population growth, high economic growth, high fossil fuel availability, and a phase out of nuclear power; and the lowest emission scenario - IS92c - assumes low population growth, low economic growth, and severe constraints on fossil fuel supplies.

Understanding how CO₂ concentrations in the atmosphere will change in the future requires carbon cycle models which model the relationship between emissions and atmospheric concentrations. The estimated CO₂ concentration in the atmosphere for each emission scenario (calculated using the Bern model) is shown in the second figure. All scenarioes show increased concentrations that are well above pre-industrial levels by 2100 (75 to 220% higher).

Climate induced environmental changes cannot be reversed quickly. Even if the anthropogenic emissions of CO₂ are stabilized or reduced, the CO₂ content in the atmosphere will still increase for some time.