Study: Global Reforestation Is the #1 Way to Fight Climate Change

Stout Memorial Grove in Jedediah Smith Redwoods State Park, Northern California.
Stout Memorial Grove in Jedediah Smith Redwoods State Park, Northern California. Photo: MChee2.

According to new research published in the journal Science, restoring forest land on a global scale could dramatically reduce the amount of carbon in the atmosphere and thus help to mitigate the impacts of climate change and biodiversity loss. While most of us know the importance of planting trees to fight climate change, this new study has quantified how many trees we need to plant and how much carbon they could absorb.

The scientists used direct measurements of forest cover to create a model of how and where parts of the Earth could be reforested. They used geospatial imaging to determine how much additional tree cover could be grown in areas that are not currently being used for agricultural and urban uses. (They did include current grazing land as areas where we could potentially to regrow forests. As is happening in the Amazon Rainforest, entire forests have been destroyed to allow grazing for livestock.)

The study found that existing natural ecosystems could support an increase of over 25 percent of forested land that included 500 billion new trees. If we plant this many trees, we could reduce atmospheric carbon by 25 percent.

The scientists found there is room for an additional 0.9 billion hectares (about 2.2 billion acres) of tree canopy cover in areas around the Earth that already naturally support woodlands and forests.

Tropical rainforest canopy, near Cairns, Queensland, Australia.
Tropical rainforest canopy, near Cairns, Queensland, Australia. Photo: Willem van Aken, CSIRO.

Planting this many trees in these areas could store over 200 gigatons of carbon. Just for comparison, according to another data set, since 1850 (roughly the start of the Industrial Revolution in the U.S.), we have released about 910 gigatons of carbon into the atmosphere.

Because trees are so effective at absorbing carbon and because they’re relatively inexpensive and easy to grow, according to the study, restoring the Earth’s forests is currently the most effective thing we can do to fight climate change. However, climate change as it’s happening right now is already impacting forests and it will continue to impact new trees that are planted, the report says. Thus, it’s crucial that we change from our current trajectory and reduce our carbon emissions.

Larch forest, Eastern Siberia
Larch forest in Eastern Siberia. Photo: Franz Hafner.

The authors of the report underscored the need for immediate action. In an article by Damian Carrington in the Guardian, the lead researcher on the study, Professor Tom Crowther of the Swiss university ETH Zürich, emphasized that we must reverse current trends in greenhouse gas emissions and drop them to zero as a reforestation project of this magnitude will take 50-100 years to be effective.

One of the blessings of planting trees, said Crowther, is that trees are “a climate change solution that doesn’t require President Trump to immediately start believing in climate change, or scientists to come up with technological solutions to draw carbon dioxide out of the atmosphere. It is available now, it is the cheapest one possible, and every one of us can get involved.”

Planting trees in India.
Planting trees in India. Photo: Shrinivaskulkarni.


Organizations that plant trees:

Nature Conservancy

Friends of the Urban Forest

One Tree Planted

National Forest Foundation

Another idea: Google “native trees” + your geographical area and plant some in your own community with your friends and neighbors. I know I’m going to. :o)

Mexican spotted owl.
Mexican spotted owl. Photo: USDA.

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