How much does it cost to plant millions of trees?

Global reforestation projects are increasingly driven by anxiety about climate change.
Young activists are being motivated to take part in the global business of tree planting due to increasing worries about the effects of climate change. They're also being inspired by a growing number of social media campaigns like #TeamTrees, #HugATree and #TreesForLife. 

The BBC's Fergus Nicoll has been exploring the global tree-planting phenomenon - to learn more about its scale and potential.

(Image: A tree being planted. Credit: Getty Images.)