Planting trees sound like a good idea, but I don’t think we should go around telling other people to plant trees on our behalf.
“It is true that you could store lots of carbon if you planted more trees. But when I engaged with European scientists about why you can’t plant trees in Europe, they say, ‘Well, we are using that land.’ There is a sense that land in Africa is available and can be used to fix global issues.”
Besides, it is far from settled whether planting more trees in Southern Africa’s grasslands would actually have the intended effect. “Several researchers have argued that the grassy biomes targeted for afforestation are better than forests at conserving carbon,” noted a recent paper on this subject in the Trends in Ecology & Evolution journal.
“This is partly because forests, especially plantations of eucalypts and pines, are vulnerable to high-severity fires and will become more so as the world warms. Most of the carbon stored in grasslands is below ground, where it persists through fire.”
There are other problems with indiscriminate afforestation, this paper explains. Digging up the soil to plant the trees may inadvertently release carbon into the atmosphere, because grasslands themselves are hypothesised to be formidable carbon sinks; and trees, with their deep roots, use up lots of water — leaving less for other species, including humans.
This science is not new, nor is it controversial: in fact, South Africa heavily regulates the planting of new forests because of their negative impact on water supply.
— Simon Allison, “The trouble with indiscriminate tree-planting in Africa“
I am surprised that grasses would be better carbon sinks, but it sounds like something that could be investigated.