Lithium in globular clusters

I review recent progress in mapping out and understanding the behaviour of stellar surface abundances of lithium as evidenced by spectroscopic studies of nearby globular clusters (GCs). It will become clear that these observations necessitate revisions to the canonical picture of stellar and globular-cluster evolution: stars evolve with additional non-convective mixing processes and GCs are not simple stellar populations. In spite of these complications, GCs are excellent test beds for chemical-abundance studies. Spectroscopic observations of GC stars of different evolutionary stages reveal systematic trends of surface abundances likely caused by atomic diffusion and mixing. Correcting for their combined effect on surface lithium, a stellar solution to the cosmological lithium discrepancy is likely, if not probable. However, a definitive answer can only be given once we know the effective temperatures of warm subdwarfs and subgiants to high accuracy and understand the processes which give rise to the mixing needed to moderate atomic diffusion.