I got curious and will attempt some math and duckduckgoing.
A forest can remove between 4.5 and 40.7 tons of Carbon Dioxide per year per hectare during the first 20 years of tree growth. Sauce
Humanity is currently generating around 40 billion tons of CO2 per year. Sauce
So now some simple math: it would take between 1 billion and 10 billion hectares of forests, depending on their maturity, to keep up. 100 hectare = 1 km^2^ sauce, so this means 10 to 100 million km^2^ of forests.
Earth's total surface area is 510 million km^2^. sauce.
Of that, here's a quick breakdown:
So 10ish percent of the 510 million km^2^ of land on earth, or around 5.1 million km^2^ is a good candidate for tree planting. That's not enough if we want to sequester all the carbon produced by humanity. Without getting to net zero global warming will continue. The best we can do is slow it down. More disconcertingly, our appetite for energy is only increasing. The good news is that we're really starting to see large scale wind and farm operations ramping up, but there are still a lot of power plants scheduled to come online in the next two decades.