State of the Climate - 2012
Sources of Carbon Dioxide
CO2 levels are rising in the atmosphere and ocean.
About 50 per cent of the amount of CO2 emitted from fossil fuels, industry, and changes in land-use stays in the atmosphere. The remainder is taken up by the ocean and land vegetation, in roughly equal parts.
The extra carbon dioxide absorbed by the oceans is estimated to have caused about a 30 per cent increase in the level of ocean acidity since pre-industrial times.
The sources of the CO2 increase in the atmosphere can be identified from studies of the isotopic composition of atmospheric CO2 and from oxygen (O2) concentration trends in the atmosphere. The observed trends in the isotopic (13C, 14C) composition of CO2 in the atmosphere and the decrease in the concentration of atmospheric O2 confirm that the dominant cause of the observed CO2 increase is the combustion of fossil fuels.
Measurements from Cape Grim, Tasmania, showing: increasing monthly mean background concentrations of CO2 (parts per million, top) showing that the CO2 growth rate has increased above the linear trend (dashed line) through the measurement period; the decreasing ratio of 13CO2/12CO2 in the atmosphere (expressed as δ13CO2 in units of per mille, centre); and decreasing concentration of oxygen in the atmosphere (expressed as the ratio of oxygen to nitrogen, bottom), including measurements at Cape Grim from both CSIRO (light green) and Scripps Institution of Oceanography (dark green).
The Bureau has been observing, reporting and researching Australia’s
weather since 1908. CSIRO has been undertaking atmospheric and
marine research for more than 60 years. Together our scientists
continue to build the body of knowledge that allows people to
understand the changes in our climate that we are observing and
prepare for any future changes.