CO2 and Global Temperature Change

The graph below depicts what we know. The global temperature is rising corresponding to a rise in CO2 in the atmosphere. Carbon, unlike some other pollutants such as nitrogen dioxide does not break down or disappear, it is only stored in other forms. The major carbon sinks as they are called are the reservoirs of fossil fuel which we are rapidly releasing, and to a lesser extent, forests which we are cutting and burning, and the ocean.

Anthropogenic Sources of atmospheric CO2: forest fires are included, for comparison, and because a significant increase in forest fire activity is caused by clearing of tropical forest for agriculture.

Sources: Carbon Dioxide Information Analysis Center

CO2 from 1832 to 1978 from Law Dome Ice Core DEO8.
CO2 from 1979 to 1998 from Mauna Loa
Temperatures - smoothed data from annual global averages Global Temperature Anomalies
Projected growth in CO2: Without restraint the level of CO2 will grow at an increasing rate because of the rapid industrialization of less developed countries especially china, and the expanding population. Energy Outlook 2000 published by the U.S Department of Energy estimates carbon U.S. emissions will grow by 1.3% per year through 2020.
U.S Carbon Emissions By Primary Fuel (million metric tonnes)




 % increase/Y




 Natural Gas















Source: U.S. Energy Information Administration, DOE

Stabilization of atmospheric CO2 at a level roughly twice the 1970 level is an optimistic, but achievable goal and will require the reduction of C emissions to about 2 gigatonns/year from the current level of close to 8GtC/year. In order to stabilize CO2 at lower levels either requires an immediate reduction of emissions, or achieving a negative level of emissions in the future. Given the rapid increase in CO2 levels in the past decade despite the Kyoto Protocols and numerous other international conferences, a tripling seems more likely. Below is one of the possible profiles leading to a stabilization of CO2 prepared by the Intergovernmental Panel on Climate Change.
How much is 8 gigatonnes? To put the problem in an biological perspective, to compensate for the annual addition of 8 Gigatonnes of C would require planting a forest 4 times the area of the entire United States and never letting the trees die and decay.

Source: Technical Paper III Stabilization of Atmospheric Greenhouse Gasses: Physical, Biological and Socio-economic Implications

Note: to insure objectivity IPCC papers are subjected to peer review by 93 scientists in 27 countries before publication.
Consequences of CO2 levels of 650ppm:
1. Temperature rise of at least 1.5 degrees C. over the next 100 years. Because heating would be uneven, an average temperature rise of 2° C would result in a rise of 4° to 5° C in some areas.
2. Sea level rise of 2 feet or more over the next 100 years.
3. More erratic weather patterns, storms droughts, floods, temperature extremes.
4. Slowing of ocean currents and possible disruption of present patterns.
These estimates are approximate because other greenhouse gasses such as methane could have a significant influence on the ultimate outcome depending on how they are managed in the future.
We are only beginning to understand the human and environmental consequences of such changes and cannot yet make accurate predictions of the level environmental disruption, species extinction or human suffering. Past climactic change such as warming after an ice age occurred at a much slower rate giving plants and animals time to adapt and move. The IPCC report estimates the cost of climate change at 1.5-2% of Gross Domestic Product per year. In current $ that is $300 to $400 billion/year, but the effects are likely to be more severe in some locations than others.
Source: IPCC Technical Paper III
Note: The lines represent different levels of stabilization, and different paths to achieve that level. The graphs also show that temperature and sea level continue to rise for some time after the carbon emissions are reduced.
Further Reading:
Carbon Dioxide Analysis Center
National Energy Information Center,
EPA site for global warming - impacts -
A selective list of resources for global climate change
A good summary of the greenhouse effect from the Encyclopedia Britannica.
Another interesting site with good graphics and possible mitigation techniques:
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