Greenhouse gas emissions from more than 100 large companies taking part in two prominent international climate initiatives fell by more than one-third between 2015 and 2019, according to a new analysis. The findings suggest that participating companies are on track with action to keep global warming below 2 °C – but need to improve the transparency and rigor with which they report their progress.

“There are things to celebrate, but also a lot to improve,” says study team member Ivan Ruiz Manuel, a graduate student at the Delft University of Technology in the Netherlands.

Voluntary programs to cut greenhouse gas emissions are becoming popular among companies around the world. Studies have suggested that such corporate climate initiatives have the potential to bring about emissions cuts in addition to those set out in national goals. But few studies have evaluated how those initiatives are doing in practice.

In the new study, Ruiz Manuel and Delft University of Technology professor Kornelis Blok gathered publicly available data from 102 of the largest companies participating in the Science-Based Targets initiative (SBTi), which evaluates and gives the stamp of approval to companies’ emissions reduction targets, and RE100, which encourages participating companies to switch to renewable electricity sources. Of the firms included, 26 participated in both programs.

The researchers evaluated the participating companies’ progress in cutting emissions between 2015 and 2019, breaking down the results geographically and by economic sector. The targets for reducing greenhouse gas emissions set by participants in both initiatives are in line with the Paris Agreement, the researchers report in the journal Nature Communications.

“This in itself is quite an achievement: organizing and guiding such a diverse group is no easy task,” Ruiz Manuel says. “We also saw how, as a group, companies have followed up on the targets, even exceeding them in some cases.”

Members of SBTi bested their collective emissions reduction target during the period analyzed in the study. Companies participating in RE100 increased the amount of renewable electricity they used by an average of 31.2% per year. Overall, the participating companies reduced their greenhouse gas emissions by a total of 288.2 megatonnes carbon dioxide over the study period.

On the other hand, a whopping 86% of these reductions came from just eight utility companies and energy-intensive industry firms that were members of SBTi. The result “highlights the importance of decarbonizing our power generation and energy-intensive industries,” Ruiz Manuel says. It also suggests that what kind of members a corporate climate program attracts may be more important than the number of members it has, he says.

Most of the participants in the two programs did not reduce fossil fuel use in their own business operations, but instead achieved emissions cuts by purchasing renewable electricity. That’s an easy first step for corporate climate action and “is something we expected to see,” Ruiz Manuel says.

However, this pattern means that robust verification and transparency about where that renewable electricity is coming from are all the more important to ensure that companies’ actions really result in emissions reductions that wouldn’t have occurred anyway. And that’s where corporate climate initiatives are falling short, according to the analysis.

Three-quarters of data reported by the companies is verified with only low levels of assurance, the researchers found. And more than 70% of the renewable energy purchased by program participants is purchased from undisclosed sources or through methods that don’t have a very strong impact on increasing the total level of renewable power generation. Transparency in renewable energy sourcing actually declined over the course of the study period.

“It is crucial to pay attention to what these initiatives do going forward in terms of data transparency and energy sourcing guidelines,” says Ruiz Manuel. That will not only create accountability to make sure the programs are achieving their intended effects, but also increase public awareness when things are going right.