You may have noticed that the map showing our inventory of carbon offsets and Renewable Energy Credits includes several forestry projects. And you may have wondered how much of a difference such projects can make.

Potentially, a lot. That's the conclusion of new research published this month.

A study in Science says we could increase the world's forest land by a third without affecting current urban or agricultural land uses. At maturity, the study says, those extra forests—regrown on land where forests have been cleared—could pull out of the atmosphere two-thirds of the extra carbon that human activity has added since the Industrial Revolution.

Another study, in Science Advances, looks at restoration of tropical forests, which human activity has reduced by more than half. It suggests a method of identifying "those landscapes where implementation is likely to provide the greatest potential benefits and cost-effective outcomes."

"Restoring tropical forests is fundamental to the planet's health, now and for generations to come," said Pedro Brancalion of the University of Sao Paulo, Brazil, lead author of the Science Advances study. He was quoted in a news release.

"For the first time, our study helps governments, investors, and others seeking to restore tropical moist forests to determine precise locations where restoring forests is most viable, enduring, and beneficial. Restoring forests is a must do—and it's doable."

Thomas W. Crowther, one of the authors of the Science study, said, "Our study shows clearly that forest restoration is the best climate change solution available today." Crowther, quoted in a news release, is lead scientist and founder of the Crowther Lab, which studies global ecology at ETH Zurich, a science, technology, engineering, and mathematics university in Zurich, Switzerland.

Forests do act as carbon sinks. Trees average about 50% carbon by dry weight. However, other scientists disagree that reforestation would help as much as the Science study suggests. A Vox article by Umair Irfan lays out some of the arguments that the study has inspired.

Crowther himself acknowledges that reforestation is no silver bullet: "It will take decades for new forests to mature and achieve this potential. It is vitally important that we protect the forests that exist today, pursue other climate solutions, and continue to phase out fossil fuels from our economies in order to avoid dangerous climate change."

Still, said Jean-François Bastin, the study's lead author and a Crowther Lab researcher, "Our study provides a benchmark for a global action plan, showing where new forests can be restored around the globe. Action is urgent, and governments must now factor this into their national strategies to tackle climate change."