Many of the world's biggest companies are failing to meet their own targets on tackling climate change, according to a study of 25 corporations.
They also routinely exaggerate or misreport their progress, the New Climate Institute report says.
Google, Amazon, Ikea, Apple and Nestle are among those failing to change quickly enough, the study alleges.
Corporations are under pressure to cut their environmental impact as more consumers want green products.
Some of the companies told BBC News they disagreed with some of the methods used in the report and said they were committed to taking action to curb climate change.
The firms analysed account for 5% of global greenhouse-gas emissions, the report says - which means that, although they have a huge carbon footprint, they have enormous potential to lead in the effort to limit climate change.
"The rapid acceleration of corporate climate pledges, combined with the fragmentation of approaches, means that it is more difficult than ever to distinguish between real climate leadership and unsubstantiated," the report says.
Study author Thomas Day told BBC News his team originally wanted to discover good practices in the corporate world, but they were "frankly surprised and disappointed at the overall integrity of the companies' claims".
Amazon said: "We set these ambitious targets because we know that climate change is a serious problem, and action is needed now more than ever. As part of our goal to reach net-zero carbon by 2040, Amazon is on a path to powering our operations with 100% renewable energy by 2025."
And Nestle commented: "We welcome scrutiny of our actions and commitments on climate change. However, the New Climate Institute's corporate climate responsibility monitor report lacks understanding of our approach and contains significant inaccuracies."
FTSE 100
Meanwhile, the FTSE 100 index started the day at 7,555.67, up 0.52%, while the March contract for Brent crude was ahead 0.27% at $93.09per barrel.
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