There's more to climate change than CO2... Forests create micro climates; prevent soil erosion; help fixate water and nutrients; produce food for local populations, thus providing them income and reducing need to ship as much food to rural areas; improve yields of agriculture, so you don't need to water as much, or use as much ferilizer... And Ecosia is invested is projects to help with all of this (read their blog).

This single track kindset of climate change fight is why we get so much green washing.