The urban heat island effectConcrete and asphalt soak up and store heat all day. This is the ‘ urban heat island ’ effect – and it makes cities genuinely hazardous places to be during a heatwave. Urban trees aren’t just decoration – they’re critical climate infrastructure. Ecosia's urban tree planting projectsAside from supporting BaumEntscheid, we've partnered with groups worldwide to bring trees back into cities. And in LA and Chicago, we've partnered with City Plants and Openlands to train local residents to plant, monitor and care for urban trees themselves.