In 1963, Esso (now Exxon Mobil) patented a design for a "novel and highly efficient electrode" for use in fuel cells -- a possible means of decreasing carbon emissions and producing cleaner-burning vehicles.

Research into this innovative technology, the company said at the time, "has been greatly accelerated."

But, as Carroll Muffett, president of the Center for International Environmental Law, likes to say, "Did you start driving a Prius in 1968?"

Muffett's point, which he supports with dozens more documents his group released Thursday, is that American oil companies were well aware of the risks their industry posed to the environment by the 1960s. And they could have taken actions to significantly reduce carbon emissions.

The new documents, Muffett said, show that oil companies "clearly preferred to invest in research to explain away the climate risks," instead of on technologies to reduce emissions.

Kim Steele via Getty Images "Burn off" oil fume flames are seen on an offshore oil platform.

The Center for International Environmental Law last month published documents showing the oil industry was aware of the potential role of fossil fuels in carbon dioxide emissions and the associated climate risks as early as 1957 -- decades earlier than had previously been documented -- and covered them up.

This second trove of documents, Muffett said, doesn't contain a "smoking gun" like the first set, but does highlight how the U.S. oil industry studied, understood and chose not to act on climate change.

"Here's still more evidence that this industry both understood climate issues [and] had the capacity to cut pollution," Muffett said. "What really emerges from our research is which side of the coin the oil companies decided to pursue."

For example, a 1980 Exxon corporate document released last month by the DeSmog Blog Project refers to existing technology that could remove carbon dioxide from power plant emissions.

"It is assumed that the major contributors of CO2 are the burning of fossil fuels," the document reads. "There is no doubt that increases in fossil fuel usage and decreases of forest cover are aggravating the potential problem of increased CO2 in the atmosphere. Technology exists to remove CO2 from stack gases but removal of only 50% of the CO2 would double the cost of power generation."

"They could have deployed it very rapidly," Muffett said of the technologies, "But they decided it was too expensive."

The American Petroleum Institute, an industry trade group, didn't immediately respond to a request for comment after business hours.

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The new documents also show that during the same period, oil companies funded research into other pollutants that may offset climate warming; carbon sinks that would reduce the need to control emissions; and alternative theories on the cause of climate change, some of which are still being tossed around by climate change deniers today.

Between the 1950s and 1970s, the industry also financed studies into how petroleum products could be used to control the climate. The research included burning oil to clear areas of fog and smog, and constructing massive "artificial heat mountains" out of asphalt to increase rainfall. As early as the 1980s, oil companies were beginning to invest in taller oil rigs that could withstand rising sea levels.

Bigger drilling rigs, Muffett said, are "an example of the profound distinction of how these companies were protecting their own interests" and not the public's.

This week, the National Oceanic and Atmospheric Administration announced that April 2016 was the 12th consecutive month to set a global temperature record.

Tom Sanzillo, finance director at the Cleveland-based Institute for Energy Economics and Financial Analysis, told Vice there is a clear potential, perhaps even likelihood, that these documents will result in litigation against oil companies.

"This looks like it's pretty serious, and it just seems to get worse," Sanzillo said.

The Center for International Environmental Law plans to release additional documents in the near future. For now, the group's new searchable database allows users to identify connections between companies, research institutes and individuals.

Check out SmokeAndFumes.org and decide what you think about the industry.