Royal Dutch Shell, one the world’s biggest oil companies, recognized that burning fossil fuels was raising global temperatures as early as the 1980s, but continued to produce and sell oil, gas and petroleum products, according to documents obtained and released by a European news site.

Shell, which has its North American headquarters in Houston and employs about 12,000 here, joins Exxon Mobil as a target of intensifying questions about what oil companies knew about the role of fossil fuels in climate change and when they knew it. Exxon, headquartered in Irving, has received the brunt of the scrutiny in recent years, also facing accusations — which the company denies — that it knew about the climate repercussions of its business in the 1980s, but hid the evidence.

Exxon is the subject of investigations by New York and Massachusetts that it misled the public and investors about climate change and the impact on its business. On Friday, Massachusetts’ highest court ruled that Exxon had to hand over documents related to the probe to investigators.

Shell, meanwhile, was sued this month by a Dutch group, Friends of the Earth Netherlands, which alleged that the Anglo-Dutch company’s business is contributing to the destruction of the planet.

Shell did not deny that allegations that it had early knowledge of the effects of fossil fuels on global warming or the authenticity of the documents released by the European news site, De Correspondent. But in a statement, the company contended that its position on climate change has been a matter of public record for decades

“We strongly support the need for society to transition to a lower carbon future, while also extending the economic and social benefits of energy to everyone,” Shell 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.”

Climate change has become a growing concern as global temperatures rise, seas warm and destructive storms, such as Hurricane Harvey, increase. Scientists blame fossil fuels for accelerating climate change because burning oil, natural gas and coal produces carbon dioxide, which traps heat in the earth’s atmosphere, a phenomenon known as the greenhouse effect.

The documents released by De Correspondent included a confidential, internal report prepared by Shell researchers in 1988. The report, entitled “The Greenhouse Effect,” described fossil fuel combustion as the leading cause of rising carbon dioxide levels and warned that oil companies would need to take action.

The report specifically mentioned the potential for significant increases in temperatures and sea levels, which could lead to the abandonment of low-lying cities. It also calculated that Shell was responsible for 4 percent of global carbon emissions from fossil fuels.

“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 report said. “The potential implications for the world are, however, so large, that policy options need to be considered much earlier. And the energy industry needs to consider how it should play its part.”

Victor Flatt, director of the Environment, Energy and Natural Resources Center at the University of Houston Law Center, said the internal Shell documents aren’t surprising, but they underscore that there was solid scientific knowledge of global warming by the late 1980s, even if the full implications weren’t clear.

The legal question for Shell and Exxon Mobil, Flatt said, is whether they misled the public and their own shareholders regarding the potential financial impact on their businesses from global warming and polices aimed at addressing it.

Climate change and efforts by governments around the world to combat it pose an existential threat to the oil industry, which in recent years has acknowledged the threat and taken steps to adjust to low-carbon environment, including increasing investments in cleaner burning natural gas and alternative energy technologies. In the 1980s and ‘90s, however, many oil companies and executives responded to global warming concerns with skepticism.

Until about a decade ago, for example,. Exxon Mobil donated money to conservative think tanks such as the Heartland Institute that dispute the scientific consensus on climate science.

“In a way, we’re actually asking (oil companies) not to sell their product and go out of business,” said Flatt, “and we’re surprised when they don’t do that.”

Exxon Mobil is now doing more to reduce emissions of methane, a potent greenhouse gas, and invest in alternative energy. Shell has made a larger public show of promoting the Paris climate accord and the company’s plan to dramatically reduce its dependence on crude oil for corporate profits.

Shell aims to cut its carbon footprint in half by 2050 — and by 20 percent by 2035. Shell also supports a potential “Sky scenario” that envisions the world achieving net-zero carbon emissions by 2070 to keep global temperatures from rising above 2 degrees Celsius, the target set by the Paris accords

At a Houston energy conference in March, Shell Chief Executive Ben van Beurden emphasized that Shell is spending more on natural gas, offshore wind farms, biofuels, carbon capture projects and the planting of trees and forests, which absorb carbon dioxide. Shell also is rolling out a program in Europe to charge about 1 or 2 cents more for gasoline to fund tree-planting projects worldwide.

"There's no other issue with the potential to disrupt our industry on such a deep and fundamental level," van Beurden said of climate change.

But Shell, in a sustainability report released this week, admitted that its greenhouse-gas emissions rose last year as the energy sector rebounded with rising oil prices and Shell added new refineries. In a separate report, the company explained how it would reduce — but not eliminate — its oil production.

jordan.blum@chron.com

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