Tree-planting has been hailed as a solution to climate change. But how much can trees really do to tackle global warming? See our research here: https://econ.st/32HXvXY Click here to subscribe to The Economist on YouTube: https://econ.st/2xvTKdy Summer 2019 - More than 38,000 fires raged across the Amazon. Fires that were man-made. Over the past 50 years almost 17% of the world’s largest rainforest has been cleared. And globally deforestation has almost doubled in just five years. Since the start of human civilisation it’s estimated that the number of trees around the world has fallen by almost half. Clearing forests increases carbon-dioxide levels but planting them could store away some of the carbon already in the atmosphere. This woman runs safaris in England. Guests are not only here to see wild animals - they’re here to see wild trees. Almost 20 years ago Isabella Tree—yes that is her real name-handed 1,400 hectares of Sussex farmland back to nature, by doing, well nothing. She thinks this is the best way to use the land to help tackle climate change. To stabilise the climate global carbon emissions need to drop to net zero by 2050. Simon Lewis is a professor of global change science. And there’s never been more global ambition to plant trees. In 2014, 51 countries pledged to plant over 3.5m square kilometres of forest by 2030 - an area slightly larger than India. The 2030 target looks likely to be met. But there’s a catch… Monoculture tree plantations like eucalyptus grow quickly but the trees are harvested every ten or so years releasing much of the carbon stored in the tree back into the atmosphere - which means that, according to some studies they’ll store only around one-fortieth of the carbon natural forests do over the long term. In fact, those pledges to plant millions of trees actually promise to store 26bn tonnes less carbon than they could. Sometimes the motives for planting forests are less green than they might appear. By 2020 Ireland ought to have cut greenhouse-gas emissions by 20% below 2005 levels. But at current rates it will have reduced them by only 5%. Planting forests might help Ireland avoid massive penalties for missing EU targets because the potential carbon these forests could store in the future can be counted as a carbon credit today. In the 1920s Ireland had the lowest forest cover in Europe at around 1%. That’s now risen to 11% and the government has set a target to cover 18% of the land with forest by 2046. And now local community groups are protesting against these monoculture tree plantations. They say they’re doing more harm than good. Tree-planting programmes invariably have an impact on the people living nearby. In east Africa one project is demonstrating what can be achieved when there’s genuine buy-in from the local communities. Green Ethiopia is a mixed-tree planting charity. The land is communally owned and co-operatives of local women receive benefits for planting trees which are protected from being harvested. Here conserving is just as important as planting. Green Ethiopia assesses whether the condition of the land is good enough to regenerate by itself. When it is—on about a third of the area the charity runs they leave it alone. Just like Isabella Tree, back in England. Monoculture plantations are often preferred because they make money. So some experts are looking to a future where carbon payments could create financial incentives for natural forests. Ultimately though, the trouble with trees tackling climate change is space For more from Economist Films visit: http://films.economist.com/ Check out The Economist’s full video catalogue: http://econ.st/20IehQk Like The Economist on Facebook: https://www.facebook.com/TheEconomist/ Follow The Economist on Twitter: https://twitter.com/theeconomist Follow us on Instagram: https://www.instagram.com/theeconomist/ Follow us on Medium: https://medium.com/@the_economist