In 2003, the science journal Nature published an article by Oxford University scientist Myles Allen titled ‘Liability for climate change’. Allen wondered aloud how to solve “the attribution problem” to demonstrate precisely how much burning fossil fuels were responsible for worsening climate-linked developments. If one could do that, he surmised, it would be possible to sue fossil fuel companies for damages.
This question gave birth to attribution science, which correlates greenhouse gas emissions with climate change. A year after posing the question in Nature, Allen and his colleagues Dáithí Stone, Peter Stott and Mark Hawkins published the first ‘extreme event attribution’ study. Using computer models, they compared human-caused, post-Industrial Revolution emissions with scenarios lacking such emissions. They concluded that man-made greenhouse gas emissions had more than doubled the likelihood of the deadly European heat wave of 2003, which killed 27 000 people.
In 2015, Fredi Otto, acting director at the Environmental Change Institute at Oxford University, and Heidi Cullen, a climate scientist who is now at the Monterey Bay Aquarium Research Institute, formed the World Weather Attribution group with the goal of providing “rapid response” analysis of climate-fuelled disasters. They wanted to show just how much human emissions had worsened those events or made them likelier to occur.
These forerunners of attribution science were subject to much scepticism when they got started, but that has largely fallen away as their models have continued to be proven. Scientists have now analysed all the carbon emissions from the Industrial Revolution until today, and can calculate just how much can be attributed to individual fossil fuel companies.
This is largely thanks to the work of Norway-born academic Richard Heede. He spent a decade researching how many greenhouse gases the world’s fossil fuel companies, cement-makers and other industrial giants had pumped into the atmosphere since the Industrial Revolution. Poring over annual company and shareholder reports, he painstakingly traced mergers and acquisitions as companies morphed and amalgamated, and a decade later reached a surprising conclusion: Just 90 companies had contributed nearly two-thirds of the world’s industrial emissions. He could even pinpoint the responsibility for the share of those emissions from companies existing today.
Attribution science is now being placed in the limelight, with a high profile lawsuit using it as the basis for litigation against an energy company. The New York attorney general is not only using attribution science in his arguments in the lawsuit against Exxon Mobil for securities fraud, but is using Heede’s data to prove that Exxon used a different internal estimate for the cost that carbon-reduction policies would have on its business than the amount it gave investors.
There are currently 13 state and local governments in the US that have filed lawsuits against oil and gas companies like Exxon Mobil, BP and ConocoPhillips, using attribution science to seek damages. These include the cities of New York, Baltimore, Oakland, San Francisco and Richmond; Imperial Beach and Santa Cruz, California; the counties of Marin, San Mateo and Santa Cruz, California; King, Washington; Boulder, Colorado; and the state of Rhode Island. Another lawsuit by Pacific Coast fishermen against Chevron also seeks climate damages.
Experts believe that the cases have a very small chance of succeeding, as the legal arguments and the science are largely untested in this arena. If the plaintiffs win, however, their argument that blame for climate change can be attributed to corporations or governments could lead to far-reaching changes in how these organisations operate.