California’s carbon offset program might be pumping millions of tons CO2 into the air, new study says

California has set an ambitious goal to be carbon neutral by 2045. One tool the state plans to use is a process called forest carbon offsets. It works by giving credits to landowners who vow to preserve forest on their properties. They can then sell those credits to polluters in the state for the right to emit more carbon.

It turns out that carbon offsets could be making the climate crisis worse by adding millions of tons of CO2 into the atmosphere. A new study says there’s a big flaw in how the state calculates the actual amount of carbon some forests can hold.

It comes down to a discrepancy in what types of trees are projected to have been used in initial calculations than what trees are actually planted, says Lisa Song, an environment, energy, and climate change reporter with ProPublica.

“You end up exaggerating the difference in the carbon stored, and that exaggeration creates a number of credits that aren't actually representing real carbon savings,” Song says.

In total, at least 20 to 39 million more tons of CO2 are being emitted under the program. In comparison, the annual emissions from 8.5 million cars emits approximately 39 million tons of CO2.

Song says the program’s regulator, the California Air Resources Board, has pushed back on the study’s findings, stating they don’t see anything wrong with the land and carbon calculations.