Very simple, plant and nurture one trillion tree's around the World. Deforestation coincides with the industrial revolution. Our planet has lost about one trillion trees in the last 500 years.
Form teams in every country and those teams could form and direct sub-teams to plant whatever types of trees grow best in their country and climates.
This could include bushes and grasses, after all; trees are just highly modified grass.
Simple, direct, low impact, and natural.
Many types of trees have multiple uses and many can regenerate after cutting.
There are fruit trees, citrus, nut, lumber, furniture, fire wood, thatch, paper, animal feed and shelter, thousands of uses for trees and grasses.Besides their huge Co2 conversion and carbon storage.
Trees give off water and Oxygen in the daytime, Pine cambium can be eaten, made into flour, the leaves of some trees can be used for human food. In sunlight a plastic bag can be put over a bunch of leaves with one corner down, to collect emergency drinking water. etc.