Chemical Elements at High and Low Redshifts

The past few years have seen a steady progress in the determination of element abundances at high redshifts, with new and more accurate measures of metallicities in star-forming galaxies, in QSO absorbers, and in the intergalactic medium. We have also become more aware of the limitations of the tools at our disposal in such endeavours. I summarise these recent developments and—in tune with the theme of this meeting—consider the clues which chemical abundance studies offer to the links between the high redshift galaxy populations and today’s galaxies. The new data are ‘fleshing out’ the overall picture of element abundances at redshifts z = 2 − 3 which has been gradually coming into focus over the last decade. In particular, we can now account for at least 40% of the metals produced by the global star formation activity in the universe from the Big Bang to z = 2.5, and we have strong indications of where the remainder are likely to be found.