Carbon dioxide accumulation in the atmosphere is the most dangerous pollution problem today. This excess of CO₂ will cause an increase in the mean global temperature which should be detectable shortly before the end of this century. This warming is caused by the greenhouse effect. CO₂ allows incoming radiation from the sun to enter the atmosphere. The heat from the earth's surface, which must radiate in the infrared region of the spectrum, is absorbed by CO₂ and water vapor, thereby raising the atmospheric temperature.

The greenhouse water-vapor coupling provides a strong positive feedback mechanism. Fossil-fuel use increases at an exponential rate of 4.3% annually. This should cause a doubling of CO₂ concentrations by between the year 2020 and the year 2075. This doubling of atmospheric CO₂ will cause an increase in the mean global temperature of about 30° to 50° C. Warmer temperatures will cause a shift in atmospheric circulation patterns. This will cause local weather patterns to change.

The results for the United States could be intensive drought, increased tropical storm activity, and a rise in the sea level caused by melting of the polar ice caps. To lessen the severity of the problem, fossil fuel consumption must be curtailed and alternate energy sources developed. Also, a global reforestation program should be undertaken to provide a large biotic  sink for CO₂ in the new few decades.