Delegates at the 2015 Paris climate talks agree that cutting back on fossil fuel use is crucial to stopping global warming. But they also urge world leaders to take another step to slash the greenhouse gases responsible for climate change: planting trees.

The world’s forests are one of our biggest allies in preventing climate change. When they’re burned (by fires or for development), they release huge quantities of carbon dioxide, or CO2, a major greenhouse gas. But planting new forests fights climate change by filtering CO2 out of the air and storing it in the trees and soil.

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Leaders at the Paris conference say replanting forests and restoring good soil could absorb up to a quarter of current industrial gases, according to the Associated Press. The place they want to start reforesting first? Africa.

"Carbon will come back to earth in trees, bushes, crops and soils, where it will bring life and prosperity," Andrew Steer, CEO of the World Resources Institute, told reporters.

Backed by the World Bank and other agencies, the World Resources Institute seeks to line up $2 billion a year to restore 100 million hectares of Africa — an area three times the size of Germany — by 2030.

Reforestation is also crucial in places such as Brazil, where 20 percent of the Amazon rainforest has disappeared since 1970, according to the Worldwatch Institute.

And it’s not just other countries: Although the United States has more trees than it did 100 years ago, our canopy — or forest cover — is shrinking. The pressure on forests in the U.S. South (the "wood basket" of the country) from climate change, development and even logging for bioenergy projects could threaten more than 1,000 species of animals and plants there in coming decades, according to a Futures Project report.

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So what can you do to help with tree-planting efforts at home and abroad?

Plant trees on city sidewalks for free. Many cities, including Chicago, New York and Sacramento, have free tree-planting programs for sidewalks and sometimes even yards. Go to your city website to see if you and your neighbors are eligible for free trees.

Volunteer with the Arbor Day Foundation, which helps organize tree-planting campaigns across the United States. Besides planting trees, you can volunteer to be a tree monitor, do tree inventories or help record and publicize tree-planting events.

Contribute to global tree-planting programs. The Nature Conservancy, for example, has a Plant a Billion Trees campaign, focusing on Brazil, the United States and China. The goal is to plant a billion trees by 2025. And check out The Canopy Project, part of Earth Day Network, which vows to plant 10 million trees in impoverished areas of the world over the next five years.

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Diana is an award-winning writer and editor with more than 20 years' experience in magazine, video, book and digital journalism, with a specialty in health coverage. She was a longtime writer and news editor at the Center for Investigative Reporting; has written for publications from the Washington Post to the Times of London syndicate; and has served as a senior and/or consulting editor at Time Inc. Health, Hippocrates, HealthDay News Service and Reporting on Health. She was also editor in chief of Consumer Health Interactive, a national health and medical web site, and has reported on finance for Blueshift Research and PBS Frontline. Before joining SafeBee, she was editor of Bioenergy Connection, a national magazine about bioenergy at UC Berkeley. Her favorite safety tip: Wear a bike helmet.