Amanda Gläser-Bligh has named her street tree Linda -- a linden, eight years old, growing outside her apartment in Berlin -- and once a week through the hot months, she carries 20 liters of water down to Linda's roots. That particular devotion is not unusual anymore: Berlin's open-source Gieß den Kiez app maps nearly a million street trees by species, age, and thirst, and 12,000 volunteers now show up with watering cans to tend them alongside city maintenance crews. The project's lead, Anna Mehrländer, found herself caught off guard by what she discovered: "I was really surprised at just how deeply people care about trees - for many people it's almost like caring for a pet." What the app understood, perhaps before its designers fully did, is that many people already wanted to help and simply needed permission - as Gläser-Bligh puts it, once you have something "encouraging you, you know it's the right thing to do." At a moment when climate change can feel impossibly large, Berlin found that the distance between despair and action was sometimes just a flight of stairs and a watering can.
