While continuing to fuel the climate emergency over the past decade, oil and gas majors relied on misleading messages rather than actually taking action to transition to clean energy, according to research released Wednesday.

The peer-reviewed study, published in the journal PLOS One, focused on two American companies, Chevron and ExxonMobil, as well as two European ones, BP and Shell—the four majors also at the center of an ongoing investigation by a U.S. House panel.

Three researchers at a pair of Japanese universities reviewed data from 2009 to 2020, examining the firms’ keyword use in annual reports; business strategies; and production, expenditures, and earnings for fossil fuels along with investments in clean energy.

“We found a strong increase in discourse related to ‘climate,’ ‘low-carbon,’ and ‘transition,’ especially by BP and Shell,” the paper states. “Similarly, we observed increasing tendencies toward strategies related to decarbonization and clean energy. But these are dominated by pledges rather than concrete actions.”

“Moreover, the financial analysis reveals a continuing business […]