The bait-and-switch of the carbon offsets market

Soil carbon sequestration findings are often oversold, writes Mark Hulbert.

CHAPEL HILL, N.C. (Callaway Climate Insights) — If we want to have less carbon dioxide in the atmosphere, then we need to release less of it.

That’s because the carbon dioxide we release today will remain in our atmosphere for a very long time — as much as 300 to 1,000 years, according to some estimates. Not only will we have to live with the consequences for the rest of our lives, but so will many generations to follow.

If we nevertheless want to continue producing carbon dioxide emissions, therefore, we need to capture the carbon and store it. This alternative approach has great appeal, since it gives us the hope of being carbon neutral while still continuing to do what we were doing before.

But is it realistic?

The carbon offset market

I’m referring, of course, to the so-called carbon offset market, where companies can go to contract with various ventures that promise to capture and store a certain amount of carbon. This market is large and growing. According to an article at, “estimates of the size of the global carbon compliance offset market range between $40 billion and $120 billion.”

Here’s an illustration at the individual level of how this market works: Many airlines and travel sites allow you to purchase carbon offsets when buying an airline ticket. Imagine that you are flying one-way from New York to LA; which, according to, would release 0.66 of a ton of CO2 into the atmosphere. This website allows you, for $20, to “offset your emissions in carbon offset projects in developing and newly industrializing countries.”

A similar transaction, though on a vastly different scale, occurs when large publicly traded companies attempt to offset their carbon emissions. Google (GOOGL), for example, claims that it has been carbon neutral since 2007, by virtue of its partnering “with more than 40 carbon offset projects to offset more than 19 million metric tons of carbon dioxide emissions.”

Despite Google’s efforts, however, there can be no denying that the company’s operations led to 19 million metric tons of CO2 emissions. The only way those emissions will be completely offset is if (a) the offsets the company contracted with successfully capture that many tons of CO2, and (b) store it for the 100+ years that it will take for Google’s emissions to work their way out of the atmosphere. We won’t know that for sure until the next century.

Early indications are not encouraging, according to a study last year from ProPublica. “In case after case,” the author, Lisa Song, wrote, “I found that carbon credits hadn’t offset the amount of pollution they were supposed to, or they had brought gains that were quickly reversed or that couldn’t be accurately measured to begin with. Ultimately, the polluters got a guilt-free pass to keep emitting CO₂, but the forest preservation that was supposed to balance the ledger either never came or didn’t last.”

Similarly, a 2016 European Union study estimated, of the carbon emissions reduction projects that were surveyed, 85% overestimated the amount of actual carbon reduction.

I’m not picking on Google in particular. They’ve been better environmental stewards than some other large multinational companies. The broader, more important point is that carbon offset projects need third-party verification and auditing over very long periods.

Soil carbon sequestration

This provides a good segue into a discussion of soil carbon sequestration (SCS) strategies, which some companies are embracing as a way to offset their carbon emissions. The core idea is that, through regenerative agricultural practices, an increasing amount of atmospheric carbon can be captured through photosynthesis and stored more or less indefinitely in the soil.

As with reforestation and other previous carbon offset strategies, the key phrase is “more or less indefinitely.” There is no guarantee that the carbon that gets stored in the soil will stay there for the many decades necessary to offset the emissions of those using SCS to reduce their carbon footprint.

Part of the reason there is no guarantee is that we don’t know enough about how carbon moves through soil over time, according to Joshua Haslun, a senior analyst at Lux Research, a research and advanced analytics firm. He and Sara Olson, director of research at Lux Research, recently co-authored a study titled Messaging and Reality are Misaligned for Soil Carbon Sequestration.

In an interview, Haslun told me that, to be successful, SCS strategies need measurement, reporting and verification systems to track over time the amount of carbon that is stored in the soil, “backed by robust regional models” that account for regional differences in soil type, properties and climate. Absent such systems, he said, “you can’t guarantee that you’re not losing lots of carbon” into the atmosphere.

The other reason there is no guarantee SCS strategies will be successful in permanently reducing atmospheric carbon is that there’s no assurance that the land that adopts regenerative agricultural techniques today will continue to employ those practices into the indefinite future. You can easily imagine scenarios in which a farm changes hands a few decades from now and its new owner employs different farming methods that release into the atmosphere much or all of the carbon that the earlier owner had so carefully captured and stored over the years.

To be sure, regenerative agriculture practices have many other benefits besides carbon capture. Those benefits include increased soil health, reduced soil erosion, and increased resilience to drought. The problem, according to Haslun, comes when SCS strategies are oversold as a solution to the climate crisis. And it certainly appears that it sometimes has been oversold. One regenerative agriculture website goes so far as to say “the solution to global warming and the climate crisis (as well as poverty and deteriorating public health) lies right under our feet.”

Haslun worries that overpromising SCS could end up being counterproductive, as it might lead many to give up on SCS strategies before they have the chance to promote good long-term agricultural management practices.

Above, the Orbiting Carbon Observatory-3 (OCO-3), aka ‘The Shaker,’ is designed to measure CO2 in Earth's atmosphere. It’s now on board the International Space Station. Photo: NASA/JPL-Caltech.