Dette er en myte. De naturlige utslippene tar del i et kretsløp der utslipp og opptak er i balanse.

De menneskeskapte utslippene kommer i tillegg og forrykker denne balansen: det er ikke totalomsetningen som bestemmer et eventuelt underskudd i en bedrift, det er forskjellen mellom utgifter og inntekter.

De menneskeskapte utslippene av klimagasser er små sammenliknet med naturens egne kretsløp hvor blant annet havets opptak og utgassing av CO2, plantenes fotosyntese og nedbrytning av organisk materiale inngår.

Dette er ikke et argument mot en menneskelig påvirkning av klima. Menneskeskapt CO2 hoper seg opp i atmosfæren, og bidrar til å varme opp kloden på en selvforsterkende måte.

Siden førindustriell tid har luftens innhold av CO2 har økt med mer enn 30 %, mens innholdet av metan har økt med 17 %. Vi må mer enn 650.000 år tilbake for å finne høyere innhold av klimagasser i atmosfæren.

Dette viser at de menneskeskapte utslippene av klimagasser langt overgår naturens evne til å ta opp disse gassene. Disse endringene i klimagasser er 20 ganger raskere enn de observerte naturlige endringene.

Fossil fuels such as gasoline, methane and propane contain mostly carbon. When these fuels are burned, they react with oxygen and produce carbon dioxide.
Because of our heavy use of fossil fuels, the amount of carbon dioxide in the atmosphere has been increasing since the industrial revolution. The destruction of forests which use carbon dioxide also contributes to the increase in carbon dioxide.

Most of the light energy from the sun is emitted in wavelengths shorter than 4,000 nanometers (.000004 meters). The heat energy released from the earth, however, is released in wavelengths longer than 4,000 nanometers. Carbon dioxide doesn't absorb the energy from the sun, but it does absorb some of the heat energy released from the earth. When a molecule of carbon dioxide absorbs heat energy, it goes into an excited unstable state. It can become stable again by releasing the energy it absorbed. Some of the released energy will go back to the earth and some will go out into space.

So in effect, carbon dioxide lets the light energy in, but doesn't let all of the heat energy out, similar to a greenhouse.

Currently, the amount of carbon dioxide in the atmosphere is increasing at the rate of about one part per million per year. If this continues, some meteorologists expect that the average temperature of the earth will increase by about 2.5 degrees Celsius. This doesn't sound like much, but it could be enough to cause glaciers to melt, which would cause coastal flooding.

At night they do. During the day, they give off oxygen.

All normal plants, in the process of photosynthesis, take up carbon dioxide by day and release oxygen. This switches over in the dark, and they then produce carbon dioxide through respiration in the same way as animals. While they are growing, they take up more carbon dioxide overall than they give out, which gets turned into plant tissues (especially cellulose and, in the case of trees, lignin).