Five scientists, working in different parts of the world, bear witness to some of the dramatic changes to our planet that have occurred in their lifetimes, as the global climate warms. Professor Sir John Lawton is an ecologist and Vice President of the RSPB. He has been bird-watching in the UK since he was a boy. He remembers bird populations that have now collapsed and has seen Mediterranean species that were once rare in the UK become commonplace: multiple canaries in the global climate coal-mine, he says. Produced by Anna Buckley for the BBC Radio Science Unit. First broadcast on Tuesday 22 May, 2018.