Many of the companies promising “net-zero” emissions to protect the climate are relying on vast swaths of forests and what are known as carbon offsets to meet that goal.

On paper, carbon offsets appear to balance out a company’s carbon emissions: The company pays to protect trees, which absorb carbon dioxide from the air. The company can then claim the absorbed carbon dioxide as an offset that reduces its net impact on the climate.

However, our new satellite analysis reveals what researchers have suspected for years: Forest offsets might not actually be doing much for the climate.

When we looked at satellite tracking of carbon levels and logging activity in California forests, we found that carbon isn’t increasing in the state’s 37 offset project sites any more than in other areas, and timber companies aren’t logging less than they did before.

The findings send a pretty grim message about efforts to control climate change, and they add to a growing list of concerns about forest offsets.