A Dutch journalist has uncovered a pile of Royal Dutch Shell documents as old as 1988 that showed the company understood the gravity of climate change, the company's large contribution to it and how hard it would be to stop it.

The oil giant commissioned a 1988 report titled The Greenhouse Effect that calculated that the Shell group alone was contributing 4 per cent of global carbon dioxide emissions through its oil, natural gas and coal products. And the report warned that "by the time global warming becomes detectable it could be too late to take effective countermeasures to reduce the effects or even to stabilize the situation."

The 1988 report said that scientists believed that the effects would become detectable late in the 20th or early 21st century.

The report was written by members of Shell's Greenhouse Effect Working Group and was based on a 1986 study, though the document reveals that Shell had commissioned "greenhouse effect" reports as early as 1981.

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The documents were found by Jelmer Mommers, a reporter with De Correspondent. They were posted on the Climate Files web site, which is sponsored by the Climate Investigations Center, an environmental activist group.

MARK THOMPSON/GETTY Documents as old as 1988 showed Shell understood the gravity of climate change.

Shell's working group knew three decades ago that the change was real and formidable, warning that it would affect living standards and food supplies and have social, economic and political consequences. It also warned that rising sea levels could impair offshore installations, coastal facilities, harbors, refineries and depots.

The documents contrast with Shell's former public stance on climate change, at least for a period of time in the 1990s. The company was a member of the Global Climate Coalition, an industry group that raised doubts about the science of climate change and opposed the Kyoto Protocol.

However, Shell withdrew from the group in 1998, with its then-president Mark Moody-Stewart saying, "We recently met them and it was concluded our differences of opinion were irreconcilable. We will not renew our subscription," according to a contemporary press report.

MARK SCHIEFELBEIN/AP The 1988 report said scientists believed the effects would become detectable late in the 20th or early 21st century.

The 1988 report estimated that in 1981, 44 per cent of carbon dioxide emissions came from oil, 38 per cent from coal and 17 per cent from natural gas.

"With fossil fuel combustion being a major source of CO2 in the atmosphere, a forward looking approach by the energy industry is clearly desirable, seeking to play its part with governments and others in the development of appropriate measures to tackle the problem," the report said.

At the same time, however, the report said that "the likely time scale of possible change does not necessitate immediate remedial action."

AIJAZ RAHI/AP The global fleet of coal-fired power plants is projected to begin shrinking by 2022.

On Thursday, Shell issued a statement about the newly released report.

"The Shell Group's position on climate change has been a matter of public record for decades. We strongly support the Paris Agreement and the need for society to transition to a lower carbon future, while also extending the economic and social benefits of energy to everyone," the company said.

"Successfully navigating this dual challenge requires sound government policy and cultural change to drive low-carbon choices for businesses and consumers. It requires cooperation between all segments of society."