"Our support extends to a fairly broad array of organizations," Gardner said in his email today. "Our financial support does not connote any substantive control over or responsibility for the policy recommendations or analyses they produce."
The UCS report also found that ExxonMobil has, through various organizations, funded a number of climate science contrarians. In the conference call, several were singled out, including Dr. Sallie Baliunas of the Harvard-Smithsonian Center for Astrophysics.
Baliunas coauthored a widely criticized 2003 article that suggested natural cycles, not human activity, are causing the planet to warm. The report was widely cited by groups that receive funding from ExxonMobil, according to UCS.
Contacted by ABC News, Baliunas declined to comment on the UCS report because she had not yet seen it.
In October, Sens. Olympia Snowe, R-Maine, and Jay Rockefeller, D-W.Va., wrote a letter to ExxonMobil CEO Rex Tillerson, asking the company to "come clean about its past denial activities."
A month earlier, Britain's scientific academy -- the Royal Society -- criticized ExxonMobil for funding groups that "misrepresented the science of climate change, by outright denial of the evidence that greenhouse gases are driving climate change, or by overstating the amount and significance of uncertainty in knowledge."
The company responded in a statement, saying "we know that carbon emissions are one of the factors that contribute to climate change -- we don't debate or dispute this."
Tillerson also acknowledged the issue of global warming in comments to a group of business executives in November, saying "the potential risks to society could prove to be significant, so despite the areas of uncertainties that do exist, it is prudent to develop and implement strategies that address the potential risks."
The full Union of Concerned Scientists report can be found here.