Governors' Wind Energy Coalition

The group examined the climate plans of 25 high-profile corporations, from Amazon to Volkswagen to Walmart, that have vowed to slash their emissions to net zero. The study found that, on average, existing plans would reduce emissions by about 40 percent — significant, but not enough to prevent the worsening effects of a warming planet.

Moreover, eight of the 25 companies excluded the type of emissions created when customers use their products, such as when motorists burn gasoline. Those emissions — known as “scope 3” — typically account for 70 percent or more of corporate emissions, according to MSCI, a financial information firm.

Some of the companies reviewed, however, took issue with the study and complained that the New Climate Institute overlooked key considerations.

Although the study did not bestow its top ranking of “high integrity” on any of the companies, its second-tier ranking went to Maersk, the Danish shipping company, followed by Apple, Sony and Vodafone. But a dozen corporations fell into the lowest level, with “very low integrity” and largely lacking credible plans for getting to net zero in the time frames they have promised.

The Swiss-American pharmaceutical firm Novartis, for instance, earned praise for reporting emissions from its own purchases of goods and services, and for buying renewable energy. But the study said that Novartis will have to opt to offset 65 percent of its emissions with what the New Climate Institute calls “nature-based carbon offsets.”

“Carbon neutrality claims that are based extensively on offsetting have the potential to mislead and their integrity is highly contentious,” the report said.

The study also found that some companies fail to promise significant reductions until close to their self-imposed deadlines.

GlaxoSmithKline, another big pharmaceutical firm, has set a “glidepath” that it argues will bring the company to net zero by 2030, an ambitious target. Under its current plan, more than a third of its emissions will be cut in the final year, and half in the final two years, the company’s public materials show.

Even as national governments face increasing pressure to do more to slow climate change, the corporate world is feeling similar pressures from activists, investors and customers. As a result, the number of new pledges has soared in the past several years, bringing both optimism and scrutiny.

“There has been such a proliferation,” said Jesse Jenkins, assistant professor of mechanical and aerospace engineering specializing in climate change at Princeton University. “It is fair to take a critical look at these commitments and what they mean and what concrete actions they entail.”

The report also praised Google for developing innovative tools to procure high-quality renewable energy. It takes aim, however, at Ikea, the giant furniture retailer that has donated half a billion dollars to join with the Rockefeller Foundation in a high-profile effort to close coal plants.

Ikea has said it would be carbon positive by 2030, meaning that on balance it would be removing carbon from the atmosphere. The retailer says it plans to take used furniture and refurbish it, thus effectively storing carbon dioxide in new chairs, sofas and beds. It is also storing carbon in land and by planting trees. Ikea’s sustainability report says that “through a circular economy, we will ensure that carbon remains stored in our products and materials for longer.”

“Carbon dioxide removals can only be considered a credible neutralization of a company’s emissions if the storage has a high certainty of permanence,” the study said. “IKEA recognizes that by storing carbon in its products, it will delay their release into the atmosphere by on average just 20 years. The release of stored carbon negates any climate impact from the original sequestration.”

Ikea could not be reached for comment.

In addition, all but one of the 25 companies will likely have to rely on offsets of varying quality, the study said. It found that “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.”

“Most companies are going through a three-step process — set the goal, get a plan to meet the goal, and take steps against that plan,” said Sarah Ladislaw, a managing director at RMI, a nonprofit devoted to eliminating carbon emissions from the economy. “The first two are much easier than the third. Many companies are taking on new challenges they genuinely haven’t solved before and that can take some time.”