A half-dozen academic journals are investigating allegations that aerospace engineer Willie Wei-Hock Soon, a prominent skeptic of the idea that humans are contributing to global warming, failed to disclose financial ties to a fossil fuel company in papers they published. And the Proceedings of the National Academy of Sciences (PNAS) is examining fresh allegations—made in a report released today by the advocacy group Climate Investigations Center (CIC)—that Soon failed to follow disclosure rules in submitting a letter to that journal. The group has also raised questions about whether Soon followed disclosure policies in publishing recent papers in several other journals, including Nature Geoscience.

Today’s CIC report is a follow-on to documents released this past February by the Alexandria, Virginia–based nonprofit and the environmental group Greenpeace that attracted widespread media attention. The groups used a federal law that promotes transparency to obtain the documents from Soon’s employer, the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Massachusetts, which detailed some of his funding sources. They include the Southern Co., a large energy concern that has opposed government action on climate change. The documents also showed that Soon had characterized a number of his technical publications as “deliverables” to Southern under a funding agreement with the company. In a statement at the time, Soon said he violated no rules, but the documents prompted the CfA and the Smithsonian Institution to open investigations into the matter.

CIC and Greenpeace also wrote letters to eight science journals and one law journal, noting that those papers did not disclose Soon’s financial ties to Southern. In each case, the groups asked whether the journal had policies requiring disclosure of potential conflicts of interest.

Today’s report describes how the journals have responded—and raises new questions about papers that Soon has published since 2012.

Six of the eight science journals told CIC they have conflict-of-interest policies; the remaining journals appear to have no policies, CIC says, or did not have policies at the time of Soon’s submissions. The Ecology Law Quarterly, published by the University of California School of Law, said the episode has prompted it to consider creating a conflicts disclosure policy for all of its journals.

Thierry Forveille, editor-in-chief of the journal Astronomy & Astrophysics, wrote to CIC that the journal has no disclosure requirement “since astronomy is sufficiently removed from any monetary consequences that we have never found that necessary.” Forveille also noted that Soon’s paper examined the behavior of stars and “makes no claim whatsoever of any relevance to climate.” Still, Forveille wrote that he was surprised to learn that Soon had identified the “totally irrelevant” paper as a deliverable for Southern. That act “certainly does not reflect very well on [Soon’s] ethical standards, but this is an issue that I don't think the journal has standing to act on,” Forveille wrote.

Publisher Elsevier, which owns four journals that published six of the questioned papers, told CIC it is investigating the matter.

The American Meteorological Society’s Journal of Climate has added a publisher’s note to a 2009 paper authored by Soon that acknowledges he received support from Southern.

In letters sent yesterday to PNAS and Nature Geoscience, CIC raises questions about two of Soon’s more recent publications. Daniel Salsbury, PNAS’s deputy executive editor, responded at once, telling CIC in an e-mail that it is looking into a May 2014 letter by Soon challenging a study of how melting sea ice affected Earth’s ability to reflect sunlight. “We have contacted Dr. Soon to determine whether any additional disclosures need to be made to our readers,” Salsbury wrote in a 9 June e-mail.

Soon had not responded to a request for comment as this story went to press.