From Gas to Stone: The Incredible Discovery About Fig Trees in Kenya

The Discovery That Changed Everything

Imagine a tree that doesn’t just absorb carbon dioxide but turns it into rock. In 2024, scientists in Kenya announced a stunning finding: certain fig trees can convert atmospheric CO₂ into tiny crystals of calcium carbonate, the mineral that forms limestone, marble, and even the White Cliffs of Dover.

Unlike most trees, which store carbon temporarily in their wood and leaves, these fig trees lock it away for millennia. When ordinary trees die, their stored carbon is usually released back into the air. These figs, however, transform carbon into a stable mineral that can persist long after the tree itself is gone.

And because they are fruit trees, they can also feed people while helping cool the planet.

The Team Behind the Discovery

The research was a collaboration among scientists from Kenya, Switzerland, Austria, and the United States, including teams from the University of Zurich, Nairobi Technical University, UC Davis, Lawrence Berkeley National Laboratory, and the University of Neuchatel.

Their results were presented at the Goldschmidt Conference in Prague in August 2024, one of the world’s leading gatherings for geochemists. That is where the world learned that some trees do not just store carbon, they mineralize it.

How the Trees Turn Air Into Stone

The process, known as the oxalate–carbonate pathway, is both elegant and surprising.

1. Absorbing CO₂: Like all plants, the trees pull carbon dioxide from the air during photosynthesis.

2. Forming calcium oxalate: Inside the tree, some of that carbon becomes calcium oxalate, a common plant compound.

3. Transformation: Microbes and chemical reactions then convert the calcium oxalate into calcium carbonate (CaCO₃), the same mineral found in limestone and seashells.

4. Crystal storage: These calcium carbonate crystals form within the wood, bark, and even the surrounding soil, effectively trapping carbon in rock form.

Most trees are like temporary carbon lockers. These fig trees are vaults, turning gas into stone that stays locked away for thousands of years.

How Scientists Proved It

To confirm what was happening, researchers used one of science’s most advanced tools: a synchrotron, a stadium-sized machine that generates ultra-bright X-rays capable of detecting chemical structures at the microscopic level.

At Stanford University’s synchrotron facility, the team found calcium carbonate crystals not just on the trees’ surfaces but deep inside their trunks and roots. That proved the mineralization was happening from within, not from environmental contamination like dust or rain.

The Star Performer: Ficus wakefieldii

Among the species studied, Ficus wakefieldii, native to East Africa, showed exceptional ability to produce calcium carbonate.

Since there are more than 800 species of fig trees worldwide, identifying the ones best at carbon mineralization could guide future reforestation and agroforestry efforts. Researchers are now testing whether other fruit trees might share this remarkable ability.

Why It Matters

This discovery could change how we think about natural climate solutions:

• Permanent carbon storage: Mineralized carbon stays locked away for thousands or even millions of years.

• Dual-purpose farming: These fruit trees can provide both food and climate benefits.

• Tropical suitability: Fig trees thrive in many of the world’s most climate-vulnerable regions.

• Agroforestry potential: Integrating them into farms could enhance soil health, crop yields, and long-term carbon sequestration.

• Nature-based innovation: Instead of relying only on technology, we can amplify what nature already does best.

A Hidden Partnership

The oxalate–carbonate pathway relies on a quiet collaboration between trees and microorganisms. Bacteria and fungi living in and around the roots help trigger the conversion from calcium oxalate to calcium carbonate. It is a powerful example of how life works together to maintain balance, and how much we still have to learn from it.

What Comes Next

Scientists are now focused on key questions:

• How much carbon can these trees lock away over their lifetime?

• Which other species share this ability?

• Can soil conditions or genetics enhance the process?

• How can we scale up planting efforts globally?

If scaled properly, fig trees could become vital allies in long-term carbon removal, natural partners to technological solutions like carbon capture.

Nature’s Hidden Genius

Perhaps the most inspiring part of this story is that these trees have been quietly turning air into stone for centuries, unnoticed. It is a reminder that nature still holds powerful, elegant solutions, and that we have only begun to uncover them.

This discovery began with curiosity, not intention. The scientists were not searching for trees that make rocks. They stumbled upon one of nature’s most astonishing climate tricks, hidden in plain sight.

What You Can Do

• Share the story. Awareness drives support for nature-based climate research.

• Support reforestation. Tree-planting initiatives, especially in tropical regions, help expand natural carbon sinks.

• Value natural solutions. Climate action is not just about machines, it is about ecosystems.

• Stay curious. Big discoveries often begin with small questions.

The Bottom Line

The discovery that fig trees can turn CO₂ into stone reframes how we think about forests and climate action. Instead of planting any trees, we can plant the right trees, the ones that make carbon storage truly permanent.

Sometimes the answers to our biggest challenges are not inventions waiting to be built. They are living all around us, growing quietly, turning air into stone, molecule by molecule.

Sources:

1. Goldschmidt Conference 2024, Prague, Presentation on calcium carbonate biomineralization in Kenyan fig trees

2. University of Zurich, Nairobi Technical University, UC Davis, Lawrence Berkeley National Laboratory, University of Neuchatel, Austrian research teams

3. Stanford Synchrotron Radiation Lightsource facility analysis

4. Studies on the oxalate–carbonate pathway and Ficus wakefieldii in East Africa