Climate Science in Legal Contexts

The document is a comprehensive glossary designed to bridge the communication gap between the scientific and legal communities in the context of climate litigation. It defines key terms across seven thematic areas: foundational scientific concepts, measurement and data methods, climate and environmental science, risk and impact, public health, Indigenous Knowledge, and socioeconomic policy. The guide emphasizes the distinctions between scientific and legal interpretations of terms like 'bias', 'significance', and 'uncertainty', and explains how attribution science and climate modeling can be used to establish causation and responsibility in court.

• Scientific and legal communities often use the same terminology differently, which can lead to courtroom misinterpretations. For example, 'bias' in science refers to 'systematic error that skews results', whereas in law it typically refers to a 'lack of impartiality or conflict of interest'. Similarly, 'significance' in science refers to statistical thresholds (often p < 0.05), while legal significance relates to 'materiality and relevance to the case'.
• Scientific uncertainty is a marker of rigorous research rather than a lack of trustworthiness. It is expressed quantitatively through error bars, confidence intervals, and p-values, or qualitatively through confidence statements. The document warns that powerful actors have used the common understanding of uncertainty to undermine confidence in climate science.
• Attribution science provides a framework for establishing legal causation by linking human activities to specific harms. It comprises four subdisciplines: trend attribution (long-term shifts), event attribution (probability or intensity of specific events), impact attribution (quantifying specific harms), and source attribution (tracing harms to specific actors).
• The 1.5°C target is a policy benchmark from the Paris Agreement rather than a physical tipping point. While crossing it is associated with increased risks and a higher chance of triggering Earth system tipping points, climate impacts escalate along a continuum where 'every fraction of a degree matters'.
• Cumulative emissions are a critical metric for determining historical responsibility and liability because temperature change is driven by the total buildup of greenhouse gases over time, not just annual outputs.
• Indigenous Knowledge systems offer distinct methodologies for understanding environmental change, such as 'Two-Eyed Seeing' (integrating Indigenous and Western science) and 'Relationality' (interconnectedness of all ecosystem components). These systems often rely on longitudinal observations and oral histories that can extend historical baselines beyond instrumental records.
• The document distinguishes between 'disinformation' (deliberately created false information to mislead) and 'misinformation' (false information shared without intent to deceive), noting that this distinction is crucial for determining legal liability and intent.
• Emissions accounting, particularly the Greenhouse Gas Protocol's Scope 1, 2, and 3 categories, is essential for tracking corporate responsibility. For oil and gas companies, Scope 3 emissions (indirect emissions across the value chain) can account for 80–95 percent of total emissions.

APA

Merner, D., Phillips, C. A., Beckett, W. S., Brown, C. A., Byron, R., Chamberlin, J., Frei, A., Frierson, D. M. W., Lavey, W. G., Lindsay, G., Loew, M. H., Mahdavi, P., Martinez, C., Raja, U., Simmons, A., Tonitto, C., Williams, E. L., & Yohe, G. W. (2026). Climate Science in Legal Contexts. Union of Concerned Scientists. https://www.ucs.org/sites/default/files/2026-04/Climate-Science-in-Legal-Contexts-4-8.pdf

Chicago

Merner, Delta, Carly A. Phillips, William S. Beckett, Charles A. Brown, Robert Byron, Johnnie Chamberlin, Allan Frei, et al. Climate Science in Legal Contexts. Union of Concerned Scientists, 2026. https://www.ucs.org/sites/default/files/2026-04/Climate-Science-in-Legal-Contexts-4-8.pdf.

Wikipedia

{{cite report |last1=Merner |first1=Delta |last2=Phillips |first2=Carly A. |last3=Beckett |first3=William S. |last4=Brown |first4=Charles A. |last5=Byron |first5=Robert |last6=Chamberlin |first6=Johnnie |last7=Frei |first7=Allan |last8=Frierson |first8=Dargan M. W. |last9=Lavey |first9=Warren G. |display-authors=etal |title=Climate Science in Legal Contexts |publisher=Union of Concerned Scientists |date=March 2026 |url=https://www.ucs.org/sites/default/files/2026-04/Climate-Science-in-Legal-Contexts-4-8.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{merner2026climate, author = {Merner, Delta and Phillips, Carly A. and Beckett, William S. and Brown, Charles A. and Byron, Robert and Chamberlin, Johnnie and Frei, Allan and Frierson, Dargan M. W. and Lavey, Warren G. and Lindsay, Grace and Loew, Murray H. and Mahdavi, Paasha and Martinez, Carlos and Raja, Urooj and Simmons, Adele and Tonitto, Christina and Williams, Emily L. and Yohe, Gary W.}, title = {{Climate Science in Legal Contexts}}, institution = {Union of Concerned Scientists}, year = {2026}, month = mar, url = {https://www.ucs.org/sites/default/files/2026-04/Climate-Science-in-Legal-Contexts-4-8.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }