1898

Swedish scientist, Svante Arrherius, puts forward the theory of the greenhouse effect and calculates that doubling of carbon dioxide in the atmosphere will increase temperatures by 5°C to 6°C

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1956

US weapons researcher Gilbert Plass pursues climate research in his free time and analyzes how carbon dioxide traps heat. He announces that climate change could be a severe problem to future generations.

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1959

The physicist Edward Teller tells the American Petroleum Institute (API) a 10% increase in CO2 will be sufficient to melt the icecap and submerge New York. “I think that this chemical contamination is more serious than most people tend to believe.”

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1965

Lyndon Johnson’s President’s Science Advisory Committee states that “pollutants have altered on a global scale the carbon dioxide content of the air”, with effects that “could be deleterious from the point of view of human beings”. Summarising the findings, the head of the API warned the industry: “Time is running out.”

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1970

Shell and BP begin funding scientific research in Britain this decade to examine climate impacts from greenhouse gases.

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1977

A recently filed lawsuit claims Exxon scientists told management in 1977 there was an “overwhelming” consensus that fossil fuels were responsible for atmospheric carbon dioxide increases.

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1979

The First World Climate Conference, sponsored by the World Meteorological Organization, is held in Geneva, Switzerland. Extremeweather events earlier during the decade had focussed public attention on climate.

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1981

An internal Exxon memo warns “it is distinctly possible” that CO2 emissions from the company’s 50-year plan “will later produce effects which will indeed be catastrophic (at least for a substantial fraction of the Earth’s population)”.

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1982

Ice cores from the Greenland ice sheet show dramatic temperature oscillations in a single century from the past, an extremely short period for climate change. Scientists also call 1981 the warmest year on record.

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1988

The Nasa scientist James Hansen testifies to the US Senate that “the greenhouse effect has been detected, and it is changing our climate now”. In the US presidential campaign, George Bush Sr says: “Those who think we are powerless to do anything about the greenhouse effect forget about the White House effect … As president, I intend to do something about it.”

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1988

A confidential report prepared for Shell’s environmental conservation committee finds CO2 could raise temperatures by 1C to 2C over the next 40 years with changes that may be “the greatest in recorded history”. It urges rapid action by the energy industry. “By the time the global warming becomes detectable it could be too late to take effective countermeasures to reduce the effects or even stabilise the situation,” it states.

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1989

US industry groups establish the Global Climate Coalition (GCC), a lobbying group that challenges the science on global warming and delays action to reduce emissions. Exxon, Shell and BP join between 1993-94.

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1990

Exxon funds two researchers, Dr Fred Seitz and Dr Fred Singer, who dispute the mainstream consensus on climate science. Seitz and Singer were previously paid by the tobacco industry and questioned the hazards of smoking. Singer, who has denied being on the payroll of the tobacco or energy industry, has said his financial relationships do not influence his research.

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1991

Shell’s public information film Climate of Concern acknowledges there is a “possibility of change faster than at any time since the end of the ice age, change too fast, perhaps, for life to adapt without severe dislocation”.

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1992

At the Rio Earth summit, countries sign up to the world’s first international agreement to stabilise greenhouse gases and prevent dangerous manmade interference with the climate system. This establishes the UN framework convention on climate change. Bush Sr says: “The US fully intends to be the pre-eminent world leader in protecting the global environment.”

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1997

Two month’s before the Kyoto climate conference, Mobil (later merged with Exxon) takes out an ad in The New York Times titled Reset the Alarm, which says: “Let’s face it: the science of climate change is too uncertain to mandate a plan of action that could plunge economies into turmoil.”  The Kyoto Protocol is negotiated to reduce greenhouse gas emissions 5.2% below 1990 levels by 2012 in the developed countries including the former communist bloc.

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1998

The US refuses to ratify the Kyoto protocol after intense opposition from oil companies and the GCC.

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2005

Kyoto Protocol enters into legal force on Feb 16. The treaty was ratified by more than 140 countries. Concentration of carbon dioxide now stands at 372 parts per million, higher than at any time in at least the past 420,000 years.

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2009

The US senator Jim Inhofe, whose main donors are in the oil and gas industry, leads the “Climategate” misinformation attack on scientists on the opening day of the crucial UN climate conference in Copenhagen, which ends in disarray.

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2013

A study by Richard Heede, published in the journal Climatic Change, reveals 90 companies are responsible for producing two-thirds of the carbon that has entered the atmosphere since the start of the industrial age in the mid-18th century.

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2016

The API removes a claim on its website that the human contribution to climate change is “uncertain”, after an outcry.

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2017

Exxon, Chevron and BP each donate at least $500,000 for the inauguration of Donald Trump as president.

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2019

Mohammed Barkindo, secretary general of Opec, which represents Saudi Arabia, Kuwait, Algeria, Iran and several other oil states, says climate campaigners are the biggest threat to the industry and claims they are misleading the public with unscientific warnings about global warming.