I'm Paul Fraser, and I have been working with CSIRO in the greenhouse gas team since 1974.

We were one of the first non-American laboratories to take up that idea of measuring carbon dioxide in the atmosphere, to try and understand where it's coming from. 

[Images of a man removing and replacing metal flasks in a laboratory.]

The CSIRO greenhouse gas network consists of about 10-15 stations around the world. At those stations, air is collected regularly and put into flasks, and they're shipped back to our laboratory here at Aspendale, and that's where we do the analysis of all the greenhouse gases, on those samples. 

[Images of instruments on a cliff top. Images of a man tightening seals around glass pipes in a laboratory.]

The science has evolved significantly at a number of levels. We can measure many, many more greenhouse gases now than we could in the 1970s, and we can measure them much more accurately.

[Images of pipes and taps, a man, and a machine that draws a graph.]

There are a number of versions of carbon dioxide, and they're made up of different carbon - what we call carbon 12, carbon 13 & carbon 14. When we get carbon dioxide coming from fossil fuels, it has no carbon 14 CO2. So by making these measurements of carbon dioxide - not only concentration, but the isotopic composition - we are able to tell whether the carbon comes from the ocean, from the biosphere from plants, or from fossil fuels. And the end result is, we have proved with these records, that the increase in carbon dioxide in the atmosphere is essentially driven by the burning of fossil fuels. 

[Animation of a graph from 1880 to 2015 of CO2 flux from fossil fuels and industry, also from land use change. Land use change rises slightly; fossil fuels and industry rises rapidly from 1950 onward. The label says: CO2 emissions continue to rise and re mainly from fossil fuel burning.]