The idea was floated by scientists and President Donald Trump’s government alike: Planting an astronomical amount of trees — a trillion, some estimates suggest — may help pull us out of the deep trouble carbon dioxide emissions are causing.
The prevailing consensus among researchers is that planting trees can make strides toward lowering emissions. Trees sequester carbon dioxide, so having more of them does help to soak up the planet-warming gas.
But when it comes to planting all those trees, where you plant them may matter as much as the planting itself.
It turns out the key is planting trees in existing forests that aren’t as tree-filled as they could be, researchers argue in a study published Monday in the journal Proceedings of the National Academy of Sciences.
By thickening up forests that are currently under-stocked with trees, humans could increase their carbon sequestering capacity by 20 percent, the study finds.
To arrive at that estimate, researchers looked at data for 130,000 forests in the United States. That covers nearly 1.4 million trees in US forests mitigating carbon pollution.
The researchers compared future possibilities with current estimates: Right now, forests can offset around 14 percent of carbon dioxide emissions every year.
But events like wildfires have wiped out many of the carbon-storing trees on those plots of land. By restoring forests and allowing them to re-grow, the carbon intake could also increase. Fully restocking all of the under-stocked forests in the country, the researchers find, could increase uptake of carbon by around 20 percent, eliminating more than 187 metric tons of carbon dioxide each year.