Over 200 of the world’s largest companies have vowed to get to net-zero emissions by 2040, signaling how seriously they’re taking climate change. But a recent analysis has found that many of those firms aren't doing nearly enough to back up their promises.

Their plans would reduce emissions by an average of only 40%, according to the report by the New Climate Institute, an independent organization that promotes efforts to slow climate change. That’s a significant reduction, but nowhere near the companies’ stated goals.

“We went in naively optimistic about what we might see,” Thomas Day, an analyst at the New Climate Institute and author of the study, said in a statement. “We were disappointed we didn’t find a lot more creativity that we expected to find.”

The report examined the climate plans of 25 large and high-profile companies that have pledged to get to zero carbon emissions in the coming decades, including Amazon, Apple, Google, and Walmart. Many of those companies planned to offset emissions by buying credits from projects that remove carbon dioxide from the atmosphere.

The problem, the researchers said, is that many of those projects are unreliable and overpromise. “At least two thirds of the companies rely on removals from forests and other biological activities, which can easily be reversed by, for example, a forest fire,” the report said.

But companies argued that they are still well ahead of what many major countries are doing to prevent further destruction caused by carbon emissions and climate change. The report, some companies argued, failed to take into account for all of their plans.

GlaxoSmithKline, for example, says it will use a “glidepath” to reach its net-zero goals. Under its plan, the company would cut half of its carbon emissions by 2028 to 2030. So while the pharmaceutical giant may not appear to be on track today—"With its carbon reduction pathway, GSK does not send signals for short-term climate action," the report says—its efforts will speed up considerably over time.

Meanwhile, the report found that Amazon’s carbon-neutral plan was “low integrity”, meaning that it's unlikely to meet its goal. But the company said in a statement that it was still committed to hitting its net zero target by 2040, a decade ahead of the date world leaders had set in the Paris Agreement for their country's to become net zero overall. Amazon plans to power its operations with 100% renewable energy by 2025, deliver half its shipments with net zero carbon by 2030, and deploy 100,000 electric delivery vehicles by 2030, the statement said.

Benjamin Ware, the global head of climate delivery and sustainable sourcing at Nestlé, also said the report didn’t fully examine his company’s plan. “We welcome scrutiny of our actions and commitments on climate change,” he said. “However, the report lacks understanding of our approach and contains significant inaccuracies. Nestlé’s climate roadmap has been validated by the Science-Based Targets Initiative [a corporate sustainability organization]. The work that went into it is rigorous and extensive.”

Still, Day, from the New Climate Institute, says companies are benefiting from the public perception of going green while doing little beyond “business as usual” to back their claims. “We were very disappointed and surprised at how much room for improvement there was. Companies need to be much more transparent about these goals,” he said.

The institute ranked no company's as having "high integrity" in accomplishing its goals, but it did say that one company—shipping giant Maersk—had "reasonable integrity" and transparency.

"Maersk positions itself as a leading actor in the transport sector through its proactive efforts to decarbonize shipping emissions," the report said. "However, the company does not yet provide a clear trajectory to

decarbonize emissions from electricity demand and supply chains, the relative importance of which is likely to grow with the shift to alternative fuels."