It is estimated that 30% of the worlds carbon output can be (sequested) captured through the planting of trees, kelp and grasses.
The worlds annual carbon output is estimated at 30 Billion tonnes. 30 Billion tonnes x 30% = 9 Billion tonnes. 9 Billion tonnes of carbon divided by 7.8 Billion people is 1.2 tonnes per person and at approx 15 trees to capture 1 tonne of carbon per year, it requires 17 trees to equal 1.2 tonnes.
If each person on the planet planted 17 trees a year we could capture 30% of the worlds annual carbon output.