If we planted trees on every square meter outside of current cities (and let them grow without disturbing them), would that make a dent in carbon sequestration?
Serious question. Planting trees and re-growing ecosystems seems like a simple, straightforward solution, but I feel like it's a red herring.
Afforestation pretty much linearly absorbs carbon based on the size of the area you cover with trees, as a percentage of current forest area.
So if we doubled the size and carbon trapping of all the forests on earth, yes, it would make a big dent (solve the problem entirely, maybe). But that's unrealistic, because forests currently cover 30% of the land area of the planet, so we're practically never going to get to 60% forest coverage. It would involve giving up important things like farming.
It's not entirely a red herring, it will undoubtedly be a big part of climate change mitigation, but the first and most important step is to stop pumping oil out of the ground and burning it, like the article.
There's something you've missed there: forests - not just trees but the forest's understory, the animals living in it, the microbes in the soil etc - sequester carbon constantly. It isn't just "how much does the tree weigh, we've sequestered that much", it is about the ecological processes involved.
To give a fairly obvious example, think about deciduous trees: once a year they shed a large amount of carbon (leaves) which then goes into the soil. The nitrogen content is used for matter for plants, while the carbon is not.
Over time, this deposits more and more carbon in the ground itself. This is a good, safe place for it, and the model above is one of the simplest. Ecosystems are great at this stuff if we stop setting them on fire or otherwise killing everything.
Well, the studies I was summarizing basically take that into account. The raw tree mass itself is both a) not that big and b) renewed, as you say, by decomposition.
Really the purpose of forests is more in terms of soil creation and preservation, as you point out, a lot of the times in the form of shrubs, leaves, or needles and downed wood being infiltrated into substrate.
Serious question. Planting trees and re-growing ecosystems seems like a simple, straightforward solution, but I feel like it's a red herring.