Carbon dioxide
Atmospheric CO2 has increased from a pre-industrial concentration of about 280 ppmv to about 367 ppmv year 2000
(ppmv= parts per million by volume).
  1. The increase has accelerated the last 10 years, and the CO2 level now has passed 390 ppmv.
    CO2 concentration data from before 1958 are from ice core measurements taken in Antarctica and from 1958 onwards are from the Mauna Loa measurement site.
    The smooth curve is based on a hundred year running mean.
    It is evident that the rapid increase in CO2 concentrations has been occurring since the onset of industrialization.
    The increase has closely followed the increase in CO2 emissions from fossil fuels.

    Graphic: UNEP/GRID-Arendal: Vital Climate Graphics, 2001

  1. CO2 Background
    Atmospheric carbon dioxide (CO2 ) concentration was 280 ± 10 ppm for several thousand years until approximately 1750, the beginning of the Industrial Revolution, when large scale burning of fossil fuels started, while at the same time large-scale cutting of timber also took place.

    The content of CO2 in the atmosphere has risen continuously since then, reaching 367 ppm in 1999. This is an increase by 31%.

    The present atmospheric CO2 concentration has not been exceeded during the past 420,000 years, and likely not during the past 20 million years. The rate of increase over the past century is unprecedented, at least during the past 20,000 years.

    With "current energy consumption patterns the amount of carbon dioxide added to the atmosphere (as modified by absorption within natural sinks) is rising at a rate of about one half of one per cent per year."
    WMO: Climate into the 21st century.

    The present atmospheric CO2 increase is caused by anthropogenic emissions of CO2.
    About three-quarters of these emissions are due to fossil fuel burning. '
    Fossil fuel burning (plus a small contribution from cement production) released on average 5.4 ± 0.3 PgC/yr during 1980 to 1989, and 6.3 ± 0.4 PgC/yr during 1990 to 1999.
    Land use change is responsible for the rest of the emissions.
  1. ppm=parts per million. ppb= parts per billion.
    This refers to the ratio of the number of greenhouse gas molecules to the total number of molecules of dry air.
    E.g.: 300 ppm = 300 molecules of GHG per million of dry air molecules.
    PgC: Petagram of Carbon. 1 PgC = 1 Gigatonne of Carbon ( 1GtC).

    The Mauna Loa Log. Monthly update. April 2011: 393.1 ppm