The Role of Attribution Science in Climate Litigation

Didn’t get to read our third Climate Change Litigation Blog? Check it out here. Adaptation: Who Pays for this Costly Response to Climate Change?

Which country do you think is taking a leading role in examining how climate change can affect the probability and severity (risk) of extreme weather events? The answer is China! Given China is the largest emitter of greenhouse gases, it makes sense that they would, at a minimum, want to better understand the impacts of climate change. According to the London-based non-profit, China Dialogue, Chinese researchers studied the 2016 catastrophic flooding in the city of Wuhan. The researchers found that such a catastrophic flood has become almost ten times more likely over the last 55 years. They also concluded that approximately 60% of the risk (likelihood and severity) of this type of catastrophic flood can be attributed to human-caused climate change. Therefore, this event and the resulting damages can no longer be considered solely an uncontrollable supranational event. The question becomes – who is responsible, and can you attribute legal liability to them?

It is common to give attribution to someone who writes an article or to an artist who produces a work of art. The legal website defines attribution as “the act of regarding a quality or feature as a characteristic or inherent part of someone or something.” In climate litigation, “the act of regarding” typically involves scientific examination and technical research to help participants better understand climate-related causations. The objective is to produce clear evidence to facilitate attributing climate risks, damages, and potential liabilities. This field of study is sometimes called attribution science.

The “characteristic or inherent part” in legal attribution can take on different topics or themes. Columbia University’s Earth Institute has organized its Climate Attribution Database ( into the following four themes. This structure is based on the extensive work conducted by Burger, Wentz and Horton into the law and science of climate change attribution.

  • Climate Change Attribution: Examining how rising concentrations of heat-trapping gases (greenhouse gases or GHGs) in the atmosphere affect other aspects of the global climate system, such as global mean temperature, sea level, and sea ice.
  • Extreme Event Attribution: Examining how changes in the global climate system affect the probability and characteristics of extreme events.
  • Impact Attribution: Examining how changes in the global climate system affect humans and ecosystems.
  • Source Attribution: Identifying the relative contributions of different corporations, sectors, and activities to climate change.

Figure 1 illustrates how the technical output of one type of attribution can inform another type of attribution.

Each type of attribution must be addressed in order to argue who has contributed to climate change and their proportional liability for local damages. As Burger et. al. point out, attribution science can be used to establish key elements in tort litigation, such as foreseeability, causation, and injury. Of these elements, causation is identified as being the most challenging.

To succeed in a tort lawsuit, the authors argue a plaintiff needs to establish several lines of causation, such as the following:

  • Linking a specific change or event to anthropogenic climate change (e.g., sea level rise or a flooding event). Research into the flooding in Wuhan, China is a good example.
  • Linking a specific loss to that change or event (e.g., the cost of adaptation measures or residual losses that were not or could not be avoided through adaptation).
  • Linking the defendant’s conduct (i.e., greenhouse gas emissions) to anthropogenic climate change and identify the defendant’s relative contribution to the harm incurred by the plaintiff.

From a plaintiffs’ perspective this can be simplified to the following:

  • Defendants help cause climate change
  • Climate change caused specific injuries
  • Therefore, defendants caused specific injuries

The defendants will likely focus on creating uncertainty around the technical data, assumptions, and analysis generated by the plaintiffs’ experts. From either perspective, attribution science will play an important role in bringing future clarity to key issues such as causation and other elements of climate litigation.

Download the full blog for citations and additional information.

Phil Ludvigsen, PhD

Senior Associate

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Phil is a senior level business director experienced in climate change and carbon consulting services, including the development of greenhouse gas emission reports, assessment of carbon accounting systems/controls, emission baseline reductions, verification of carbon inventories and offsets, and environmental financing approaches such as green bonds. He has a proven track record of climate program development with a successful history of directing technical and financial aspects of multi-million dollar projects. Notably, Phil helped manage a $25 million strategic investment fund for American Reinsurance (now part of Munich American Reinsurance) focused on strategic environmental, health, and social loss prevention as well as cost control. In addition, he has signed off as lead greenhouse gas verifier on nearly six megatons in carbon emissions reductions under the U.S. EPA Climate Leaders program to ISO 14064-3 standards. He has also verified more than 100 facility inventories and reduction projects throughout U.S. and Canada to ISO 14064 standards, totaling more than 10 megatons of CO2e emissions. With regard to environmental financing, Phil co-developed environmental, social, and governance due diligence work stream frameworks for some of the largest pension funds in North America. Notably, he was also the first Certified Responsible Investment Professional in North America certified via the Responsible Investment Association and recognized by Investment Industry Association of Canada. Phil also sits on the Climate Bond Standards verification work group and has co-authored thought leadership on the area of Green Bonds.