After eight years of research into historical carbon emissions, Richard Heede, a researcher from the Climate Accountability Institute, has linked 63 percent of worldwide greenhouse gas emissions to just 90 “carbon major” entities. Between 1751 and 2010, about 914 gigatonnes of carbon dioxide was generated by 50 leading investor-owned, 31 state-owned and 9 nation-state producers of oil, natural gas, coal and cement.

“This study is a crucial step forward in our understanding of the evolution of the climate crisis,” former Vice-President Al Gore recently told the Guardian. “The public and private sectors alike must do what is necessary to stop global warming. Those who are historically responsible for polluting our atmosphere have a clear obligation to be part of the solution.”

Last week, the United Nation’s Intergovernmental Panel on Climate Change released its 2014 Synthesis Report, the most exhaustive and detailed report on climate change to date. Penn State’s Distinguished Professor of Meteorology, Dr. Michael Mann, told Planet Experts that that report “concludes with even higher confidence [95 percent] that the warming of the past century, and other associated climate changes, can only be explained by human activity, i.e. the burning of fossil fuels.”

Heede’s analysis, recently published in the journal Climatic Change, states that half of the estimated emissions from the 90 firms studied was released in the past 25 years – past the date when most companies would have been aware that their emissions were affecting the environment.

Speaking about the analysis, Dr. Mann told the Guardian, “What I think could be a game changer here is the potential for clearly fingerprinting the sources of those future emissions. It increases the accountability for fossil fuel burning. You can’t burn fossil fuels without the rest of the world knowing about it.”

According to Heede’s research, just 20 companies produced almost 30 percent of the total emissions since the 18th century. Nearly all of the firms are involved in fossil fuels; the remaining seven are cement manufacturers (producing one ton of cement is roughly equivalent to burning 400 pounds of coal).

Professor Naomi Oreskes, who teaches the history of science at Harvard, pointed out to the Guardian that several of the top companies in Heede’s list have invested in climate denial. “For me one of the most interesting things to think about was the overlap of large scale producers and the funding of disinformation campaigns, and how that has delayed action,” she said.

The continued emissions of greenhouse gases is already having a significant effect on global temperature rise, leading to negative climate impacts around the world. Recent analyses predict global temperatures will rise between 2°C and 6°C by 2100, triggering heat waves, drought, food shortages, sea level rise, floods and threats to human health and national security.