Glossary of Key Terms

The document defines key scientific terms used in event attribution, such as 'factual' and 'counterfactual' worlds, and outlines legal tests for proving causation, including the 'but for' and 'material contribution' tests, primarily within the context of UK law.

• In the context of climate science, attribution is the process of determining the relative contributions of various causal factors to an event using statistical significance. This involves comparing the 'factual' world, which is the "currently observed world as it exists in the context of climate change", with a 'counterfactual' world, described as a "hypothetical “control” world that has only been impacted by natural forcings and internal variability".
• The document distinguishes between two types of causation: 'necessary causation', where a factor is "always required for Y to occur", and 'sufficient causation', where the presence of a factor alone is enough for an event to occur, even if other causes are possible.
• Legal attribution of greenhouse gas emissions typically refers to assigning emissions to a "particular state, region or company" based on calculations from "fossil fuel production records".
• The document outlines several legal tests for proving causation in the UK and other jurisdictions. The 'but for' test requires showing that loss "would not have occurred but for the defendant’s breach of duty", while the 'material contribution' test allows a plaintiff to prove that negligent actions "materially contributed to the risk of harm" without needing to satisfy the 'but for' requirement.

APA

ClientEarth (n.d.). Glossary of Key Terms. https://www.clientearth.org/media/rdxbj1gq/glossary-of-key-terms-for-climate-science-and-law-seminar-ce-en.pdf

Chicago

ClientEarth. Glossary of Key Terms. n.d. https://www.clientearth.org/media/rdxbj1gq/glossary-of-key-terms-for-climate-science-and-law-seminar-ce-en.pdf.

Wikipedia

{{cite report |author=ClientEarth |title=Glossary of Key Terms |url=https://www.clientearth.org/media/rdxbj1gq/glossary-of-key-terms-for-climate-science-and-law-seminar-ce-en.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{clientearthndglossary, author = {{ClientEarth}}, title = {{Glossary of Key Terms}}, institution = {ClientEarth}, url = {https://www.clientearth.org/media/rdxbj1gq/glossary-of-key-terms-for-climate-science-and-law-seminar-ce-en.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }