Limits on Global Warming


  • A S Dennis U.S. Bureau of Reclamation Denver, CO


Consideration of the earth’s carbon reservoirs and carbon exchanges among them indicates that the concentration of carbon dioxide (CO2) in the atmosphere will increase markedly over the next 100 years and more. A doubling of atmospheric CO2, along with anticipated feedback effects on atmospheric water vapor, will be roughly equivalent in radiative terms to an increase of 5 percent in the intensity of solar radiation at the top of the atmosphere. The laws of physics predict a resultant global warming, which likely will average around 3 to 4°C, unless it is modified by other feedback effects. Concern about global warming is heightened by evidence that the average temperature at the earth’s surface has risen about 0.5°C over the last century. Global warming will be limited in intensity as the atmosphere approaches total opacity in the CO2 radiation bands and will be ended by advection of excess CO2 into the ocean depths, a process which will take several centuries. Possible measures to offset global warming include restrictions on fossil fuel consumption and active measures, such as the introduction of artificial dust clouds into the stratosphere to scatter solar radiation.




Scientific Papers