Planting trees seems to be one of the most common and economic solution to reduce CO2 and is well-recognized around the globe. It is also one of the “negative-emissions technologies” to help meet Paris Agreement targets – afforestation and reforestation.
However, climate changes are not that simple and global temperature won’t be restored just by planting trees.
Clearly, we have omitted some “negative impacts” of trees since the beginning. More efforts are definitely needed to plant trees more effective.
One of the problems is “albedo effect”. Tree leaves absorb more sunlight than do other types of land cover. Forests can reduce Earth’s surface albedo, meaning that the planet reflects less incoming sunlight back into space, leading to warming. (Nature)
Also, trees themselves are emitting CH4 and N2O, greenhouse gases.
The question, raised on New York Times with Prof. Unger at Yale in 2014, had previously attracted lots of debates.
I think it is more or less similar to companies’ earnings projection. Before launching a new product, earnings projection looks great. But it is often overestimated. Other cost items will appear, leaving the product a thinner margin.
Trees are the same. Simply planting trees probably won’t give us the estimated benefits. While I believe the “net effect” is good, we do need more sophisticated understanding and solutions regarding trees.