TREE planting doesn’t usually feature in US presidents’ speeches, UK general election battles or the business pitches of oil companies. Yet in the past year, pledges to embark on reforestation efforts have become a popular way to show you are committed to fighting climate change. There are several initiatives to plant or protect a trillion trees, to add to the 3 trillion we have today.

So how did we get here, with humble tree planting taking centre stage among the tools to stave off extreme warming? Can we really plant the numbers needed to lock up …