CO2 - the major cause of global warming

Saturday, 20 December 2008 ·


Global warming is caused by the emission of greenhouse gases . 72% of the totally emitted greenhouse gases is carbon dioxide (CO2), 18% Methane and 9% Nitrous oxide (NOx). Carbon dioxide emissions therefore are the most important cause of global warming. CO2 is inevitably created by burning fuels like e.g. oil, natural gas, diesel, organic-diesel, petrol, organic-petrol, ethanol. The emissions of CO2 have been dramatically increased within the last 50 years and are still increasing by almost 3% each year, see graph below:

Word-wide CO2 emission are steadily increasing

Graph 1: CO2-emissions world-wide by year (data from

World-wide CO2 emissions and concentrations
Graph 2: CO2 emissions world-wide by year and CO2 concentration in the atmosphere by year

The carbon dioxide is released to the atmosphere where it remains for 100 to 200 years. This leads to an increasing concentration of carbon dioxide in our atmosphere (see above on the right hand side), which in turn causes the average temperature on Earth to raise (see graph below).

Increase of world temperature

Chart 3: Increase of global average temperature for the last 20 years (source:

Recent investigations have shown that inconceivable catastrophic changes in the environment will take place if the global temperatures increase by more than 2° C (3.6° F). A warming of 2° C (3.6° F) corresponds to a carbon dioxide (CO2) concentration of about 450 ppm (parts per million) in the atmosphere.

As of beginning of 2007, the CO2 concentration is already at 380 ppm and it raises on average 2 - 3 ppm each year, so that the critical value will be reached in approximately 20 to 30 years from now. See here for some graphs about the increasing concentration of greenhouse gases and the greenhouse gas emissions by sector.

Mitigation goals for the main cause of global warming: carbon dioxide emissions

As a result of the above mentioned findings, there seems to be a consensus among the leading developed countries that the temperature increase caused by global warming must not exceed 2° C (3.6° F). For example the European Union (EU) has committed itself to this threshold already in 2005.

To reach this target the annual global CO2 emissions have to be reduced from about 28 Gigatons in 2006 to 20 Gigatons of CO2 by the year 2050 and to 10 Gigatons of CO2 by the year 2100 according to IPCC. At the first glance, this does not look like a major reduction. However one should keep in mind that the world population will grow from 6.4 billion people in 2007 to about 9.5 billion people in 2050. At the same time more and more developing countries will progress their industrialisation and as a result they will want to copy our western life style causing high CO2 emissions.

The world-wide average CO2 emissions by capita was about 4 tons per year in 2005. For North America it was about 20 tons and for Europe about 10 tons per year per capita. By 2050, the world-wide average CO2 emission per capita needs to be reduced to 2 tons per year. In the following years, the emissions will need again to be cut by half. Download and use our Excel calculator to simulate cause and effects of global warming . Based on an average carbon footprint, you can test ways to mitigate global warming yourself. Alternatively, you can have a look at some simulation results how global warming can be stopped below 2 C.

Have a look at the CO2 emissions per capita by country to see how far away from this goal value of 2 tons per year our western life style is.

In a fair world, there is absolutely no justification for the western world to pollute the Earth more than others. So we should aim to reduce our carbon footprint to 2 tons per capita per year until 2050. This means people in industrialised nations will have to cut down their carbon dioxide emissions to values reaching 10% to 20% of the current values.

The above mentioned goal can only be reached if our life style becomes a sustainable one. The first and most efficient measure is a reduction of our energy consumption. In addition, it is inevitable to make thoughts about the true meaning of life and change our personal behaviour accordingly.