Alam-Pedja Nature Reserve in Tartu County, Estonia (© Sven Zacek/Nature Picture Library)

Earth Day didn't knock gently. It kicked the door wide open. In 1970, oilsoaked beaches, burning rivers and toxic air mobilised millions into street protests. When looking away was no longer an option, conservation was forced onto political agendas, sparking landmark environmental laws and flipping planetcare from fringe concern to global priority. Every 22 April, over 190 countries pause, reflect and reassess.