No they won't. If they started tomorrow planting 100,000 trees a day, and never took a single day off, they would finish up in 2052. What kind of nursery can even grow 100,000 saplings of conifer a day?

https://podcasts.apple.com/us/podcast/the-climate-deniers-pl...

Using seedballs, you could conceivably plant 1B trees in just a couple months by dropping the seedballs from airplanes.

https://www.youtube.com/watch?v=bBbU4MQftc8

It would take a couple of years at the scale Finnish forest industry is operating.

Large parts of Europe are basically forests that have been temporarily cut down. If you let the land be, the forest will often grow back with minimal effort.

Saplings? Wouldn't it be easier to seed? Or you could plant a few more mature trees sparsely and rely on them to seed?