In December 2017, following the discovery that there are more than three trillion trees on Earth, the planting target was revised to a trillion trees and the Billion Tree Campaign became the Trillion Tree Campaign. It was found that this amount of trees would cancel out the last 10 years of CO2 emissions and sequester 160 billion tons of carbon.
Okay that's actually a useful visualization. There are about 8 billion people on the earth. That's 125 trees for every man, woman and child. "Tree" is a highly variable concept but let's take eucalyptus because it'll grow anywhere, including Australia. You can get a thousand gum trees per acre so every man, woman and child needs to plant about an eighth of an acre of trees where there are no trees any longer.
My house, coincidentally, has 3/8ths of an acre. There's already four trees on it (twelve if we're generous enough to count bushes as trees) and a house so I'm going to need to find somewhere else to put about 300 trees, even presuming I convert all of my property to forest (which I think is actually against code - power lines and the like after all).
Americans use around 50 rolls of toilet paper per capita per year. That's about a quarter a tree.