A Mexican model for offsetting carbon

What are carbon offset credits?

Walking through a pine forest in Mexico’s Sierra Norte mountains, I see peaks through a blanket of clouds. It’s breathtaking. At the top of the mountain, about 60 people dip freshly handmade tortillas into a rich, spicy pork soup as we watch paper hot air-balloons lofted into the sky, a physical manifestation of our hopes — deseos — for the future.

I’m representing Duke University at this annual ceremony for the carbon offset credits generated by the forest management practices of 12 indigenous communities in Oaxaca, Mexico. The ceremony is in Santa Maria Tlahuitoltepec (‘Tlahui’ for short), where a decision to plant pine saplings on the mountainside 18 years ago yielded results for the world to model as we work to combat climate change.


In December, a few weeks after I returned from Oaxaca, world leaders met in Poland for the 24th Conference of Parties (COP24) to discuss a global strategy to address climate change. Unlike past COPs, this conference explored the role of Carbon Dioxide Removal technologies (CDRs). CDR includes both biological efforts to store carbon through trees, wetlands and agriculture as well as technological solutions like direct-air carbon capture. Carbon offsets, a market tool that will incentivize CDRs, are critical, but few people know what carbon offsets are or how they function.

I’ve spent the last 10 years working exclusively in carbon offsets, first as the lead for the Tomorrow’s Climate Solutions consulting group and currently as the strategic coordinator for Duke University’s Carbon Offsets Initiative. I have created training materials and project protocols, as well as developed and marketed offset projects throughout the U.S., and established research connections to these projects. This project in Oaxaca is a shining example of what a carbon offset can look like if done right.

Eighteen years ago, the community of Tlahui decided to reforest an area of land that was difficult to farm because it lacked reliable water. This was not a simple decision, but the community decided, in an act of foresight, to delay any financial return and plant pine saplings.

Here’s how that decision is paying dividends now. The forest that has grown from those saplings has created positions for 20 salaried workers, communal revenue through the sale of carbon offsets, future sustainable timber production and a reliable water source thanks to the forest cover that increases and stabilizes water availability.

Now the diameter of light posts, these trees pull carbon dioxide — the primary greenhouse gas causing climate change — out of the air and turn it into wood. This reduces the levels of greenhouse gases in our atmosphere, combating climate change. Duke and businesses with emissions-reduction goals want to incentivize and reward this activity, but they need to know the trees are actually growing and storing the carbon as the project claims. Third-party assessors verify the growth in the forest and based upon measurements of tree growth can calculate how much carbon has been stored in the wood. Each ton of verified carbon dioxide removed from the air is accepted as a tradable good — called a “carbon offset,” which folks like me are interested in buying, on behalf of our institutions, toward fulfilling emissions-reduction goals.

We use these carbon offsets to counter the carbon dioxide that results from heating buildings with natural gas or flying on airplanes to attend conferences — because the trees grown in Tlahui have actually pulled the equivalent amount of carbon dioxide out of the atmosphere that we are releasing into it by flying. We buy the captured carbon and expend a one-ton credit to make a flight carbon-free, while Tlahui democratically elects to use the money received to improve its town square or public sanitation.

My hope is the leaders who met in Poland will use this project as a model. This community-focused effort in Oaxaca is a project worth replicating all over the world.

Baltimore native Tani Colbert-Sangree ( is the strategic coordinator for the Carbon Offsets Initiative at Duke University.