Attributable Damage Liability in a Non-Linear Climate

Loss and damage from anthropogenic climate change has been formally realised in the Paris Agreement of 2015 as a third pillar of climate change action next to adaptation and mitigation (Paris_Agreement_text 2018). However, political obstacles have resulted in intergovernmental compensation measures being explicitly excluded as a means of addressing loss and damage (Paris_Agreement_text 2018). Consequently, the prospect of litigation being used as a tool to pursue damages against fossil fuel companies is being examined increasingly within the legal research community (Marjanac et al. 2017).

Alongside these research efforts, the scientific basis for linking the observed impacts of climate-related events to human influences continues to develop rapidly. These scientific developments are considered potentially highly relevant to tort law suits which might deal with financial losses from an extreme weather event which has been exacerbated by human-induced changes to the climate system (Marjanac and Patton 2018).

However, many obstacles currently limit the extent to which this legal pathway can be utilised. First, immense scientific challenges exist in quantifying what monetary losses from a specific weather event can be explicitly linked back to cumulative carbon dioxide emissions from individual fossil fuel producers (Stott et al. 2016; Skeie et al. 2017; Otto et al. 2017). Second, there are numerous other, largely non-scientific, difficulties which exist in being able to quantify the estimated cost of liable damages for an individual fossil fuel company—one example lies in whether a company carries culpability for those emissions which occurred prior to scientific consensus on the role of anthropogenic greenhouse gas emissions modifying the climate system (Thornton and Covington 2016).

Regardless of these still outstanding challenges, several suits have been recently filed aiming to hold specific fossil fuel producers responsible for damages from climatic events. In the absence of specific scientific analyses attributing damages to specific parties, plaintiffs in these examples have applied the ‘market share theory’ (Marjanac and Patton 2018; United Nations Environment Programme 2017), positing that the company’s liable costs are equal to their fractional contribution to cumulative carbon dioxide (CO₂) emissions globally (Heede 2014), multiplied by the added damages due to climate change. Crucially, this theory relies on several testable assumptions, one of which is the inference that attributable climate change impacts increase linearly with cumulative carbon emissions.