Newstalk is exploring the 20 most influential moments of the past two decades.
Everyday, across the station, we're looking back at an influential moment chosen by listeners.
Today we looked at the growing threat posed by climate change in the last twenty years and the growth of campaigns around the issue - many spurred on by Swedish teenager Greta Thunberg.
Writer and sustainability advocate Emma Gleeson and Geraldine Carton, Co-founder of The Use-less project joined Kieran to discuss how he could be leading a more sustainable life.