Atomic carbon in starburst galaxies: Missing CI (J=1-0) emission in the centre of M82

CI is an important coolant in the ISM and is an excellent diagnostic of photodissociation regions associated with star formation. We discuss evidence that the CI J = 2 - 1 line is possibly much stronger than the J=1-0 line, indicating a need for high frequency observations of the nuclear regions of starburst galaxies if we wish to understand the thermal processes of the molecular gas in star-bursts.