What did Exxon executives know about global warming and when did they know it? A report by InsideClimate News published Sunday suggests the company’s own scientists gave warning as far back as the 1970s that carbon dioxide from fossil fuels were putting the planet at risk.

From a 2015 perspective, it appears that Exxon missed a golden opportunity to take a responsible course and gradually steer the world away from a reckless dependence on fossil fuels. Instead, the company spent years publicly denying global climate change and the role humans play by burning fossil fuels.

ExxonMobil spokesman Alan Jeffers responds that it’s unfair to apply today’s standards to what was highly debatable back when Exxon’s internal studies were warning of future problems.

James F. Black, a senior Exxon scientist, warned the company in 1977 that the continued burning of fossil fuels such as gasoline could lead to a doubling of carbon dioxide in the atmosphere. Trapped heat could boost global temperatures by 4 to 5 degrees Fahrenheit—even higher at the poles. Black and other Exxon scientists warned of dire agricultural effects, skewed rainfall patterns and growing desertification—amazing prescience considering today’s rising seas, increasingly violent and costly storms, severe droughts and heavy flooding.

Jeffers said the issue deserves further research. The company has never curtailed its climate-change science, he added, and its internal findings have remained consistent with prevailing scientific thought throughout the past four decades on the effects of fossil fuel usage.

Nevertheless, we can’t shake the image of Exxon’s executives dismissing the damage their primary product creates, but consistently questioning the science that underpins the global-warming argument. It reminds us of the days when Big Tobacco adamantly insisted that science was inconclusive about the cancer-causing effects of cigarettes.

Jeffers rejects that analogy, saying that Big Tobacco fabricated “junk research” that companies knew to be false. Exxon did no such thing. The company’s stand has evolved as research increasingly confirmed the effect humans were having on the environment.

The record is undeniable that former Exxon chief executive Lee Raymond, whose opinions resonated throughout Washington, led the charge against what he portrayed as a global warming boogeyman. A full decade after Black’s first scientific results were issued, Raymond called global warming “an illusion.” He derided the need for an international pact aimed at reducing dependence on fossil fuels.

Sadly, Exxon had the opportunity to lead the world toward a measured, manageable approach toward a solution. With profits to protect, Exxon provided climate-change doubters a bully pulpit they didn’t deserve and gave lawmakers the political cover to delay global action until long after the environmental damage had reached severe levels. That’s the inconvenient truth as we see it.