Afforestation is the establishment of a forest or stand of trees in an area where there was no previous tree cover. Many government and non-governmental organizations directly engage in afforestation programs to create forests and increase carbon capture. Afforestation is an increasingly sought-after method to fight climate concerns, as it is known to increase the soil quality and organic carbon levels into the soil, avoiding desertification.
The rate of net forest loss decreased substantially over the period 1990–2020 due to a reduction in deforestation in some countries, plus increases in forest area in others through afforestation and the natural expansion of forests. A 2019 study of the global potential for tree restoration showed that there is space for at least 9 million km2 of new forests worldwide, which is a 25% increase from current conditions. This forested area could store up to 205 gigatons of carbon or 25% of the atmosphere's current carbon pool by reducing CO2 in the atmosphere and introducing more O2.
Afforestation boasts many climate-related benefits. Several new studies suggest that forests attract rain, which may explain why drought is occurring more frequently in certain parts of the world such as western Africa, where trees are more sparse.
A 2017 study gives the first observational evidence that the southern Amazon rainforest triggers its own rainy season using water vapor from plant leaves, which then forms clouds above it.
These findings help explain why deforestation in this region is linked with reduced rainfall. A 2009 study hypothesizes that forest cover plays a much greater role in determining rainfall than previously recognized. It explains how forested regions generate large-scale flows in atmospheric water vapor and further underscores the benefit of afforestation in currently barren regions of the world.
Afforestation helps to slow down global warming by reducing CO2 in the atmosphere and introducing more O2. Trees are carbon sinks that remove CO2 from the atmosphere via photosynthesis and convert it into biomass.