Why planting trees alone won’t solve the climate change problem?

As the world races to stop climate change, Governments, Business Leaders, YouTubers and Celebrities are calling for the planting of millions, billions or even trillion trees to solve climate change.

Planting trees is seen as a straightforward, relatively inexpensive, ready-for-prime time solution to climate change.

But, could massive tree planting actually slow climate change?

Trees and Carbon

Carbon dioxide is the main gas that causes global warming. Through photosynthesis trees and other plants transform carbon dioxide from the atmosphere into carbohydrates, which they use to make their tissues, stems, leaves and roots.
Earth holds, by one estimate as many as 3 trillion trees. And the world oceans and land-based ecosystems, such as forests absorb half of the carbon emission from fossil fuel burning and other industrial activities.

But the ‘Devil is in the Details”

In large scale afforestation, there is a lot of emphasis on the number of seedlings planted, and too little time is spent on how to keep the trees alive in the long term. And there is not enough focus on how different types of forests sequester different amounts of carbon.

Here are some of the ways in which forests themselves can have an effect on climate:
1. Trees are dark, at least compared to other things that blanket the land. As a result, planting more trees typically makes the land darker. Since dark surfaces absorb more heat, a dark tree-covered surface will trap more of the sun’s heat and warm the local climate.

2. Adding trees to snow-covered regions, could increase the absorption of solar radiation leading to warming in subtropics.

3. The other thing trees do is emit volatile chemicals into the air. These chemicals stick together to form tiny floating particles called aerosols, which act as seeds for cloud droplets. This creates more low clouds which scatter sunlight into space.

4. At the moment a lot of trees being planted are a monoculture of fast-growing commercial species like acacia or eucalyptus. These have virtually no biodiversity benefits and may even replace the existing biodiversity.

As a result of a complex interaction between the forests and climate system, there exists a delicate balance between trees’ ability to take carbon dioxide, reducing warming and their tendency to trap additional heat and thus creating warming. Hence, planting trees only helps in stopping climate change in certain places.

Planting trees is certainly a part of the solution to climate change, but it is an unreliable way of permanently sequestering anthropogenic carbon emissions.

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