WEATHERING THE STORM OF GLOBAL CLIMATE
LITIGATION: ENABLING JUDGES TO MAKE SENSEOF SCIENCESANDRA NICHOLS THIAM,* JARRYD C. PAGE,† JOHN M. DOHERTY,‡ AND
TIM NAU§
ABSTRACT
Across the world, judges are increasingly being asked to make decisions on litigation related to climate change. As climate impacts increase in severity overthe coming decades, more cases are certain to follow. These cases sometimes
require judges to understand both the basic, well-established principles of climate science in addition to cutting-edge techniques in climate change attribution—a rapidly growing scientific field that seeks to identify the link, if any,
between greenhouse gas emissions of a given source and the occurrence or
impacts of a particular weather event. Here, we introduce the general concepts
of climate science and climate change attribution and discuss the relevance of
these scientific topics to select high-profile cases that have been brought before
various national and international judicial bodies.
Moreover, judicial education plays a critical role in preparing judges for
emerging issues relevant to their dockets. The growing number of climate cases
suggests climate science is one such issue. To help judges make sense of climate
science and its relevance, the Environmental Law Institute’s Climate Judiciary
Project is taking steps to bridge the divide between scientists and judges throughspecialized educational programming on several climate science topics. These* Sandra Nichols Thiam, JD (University of Virginia), is Vice President of Research and Policy
and Director of Judicial Education at the Environmental Law Institute. Thiam works to promote
rule of law and good governance, advising governments on comparative best practices, andC 2024,designing and implementing training programs for a broad spectrum of stakeholders. V
Sandra Nichols Thiam, Jarryd C. Page, John M. Doherty, and Tim Nau.
†
Jarryd C. Page, JD (The George Washington University Law School), works at theintersection of climate change, policy research, and education. He is a Staff Attorney at theEnvironmental Law Institute with experience in both U.S. and international environmental law
and policy issues.
‡
Dr. John M. Doherty is a geoscientist working at the intersection of climate science, law, andjudicial education. He is the Science Fellow at the Environmental Law Institute’s Climate
Judiciary Project. Dr. Doherty holds a Ph.D. in Earth Sciences, an M.S. in Environmental Science,
and a B.A. in Political Theory.
§
Tim Nau, M. Iur. (University of Münster), LL.M. (The George Washington University Law
School) was a Visiting Researcher and Law Clerk at the Environmental Law Institute and iscurrently a Legal Research Assistant with the Chair for US Law, Professor Dr. Kirk W. Junker, at
the University of Cologne, Germany.

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efforts provide judges with the information and tools that they need to makeinformed decisions on the storm of litigation coming to their courtrooms, wherever they may be.
I. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
II. A REVIEW OF CLIMATE SCIENCE AND WHAT HAPPENS WHEN
IT MEETS THE LAW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A. Climate Science and Climate Change Attribution . . . . . . . . .
B. How Climate Science and the Law Collide . . . . . . . . . . . . . .
III. CLIMATE SCIENCE IN COURT CASES . . . . . . . . . . . . . . . . . . . . . .
A. Upcoming Opportunities to Grapple with Climate Science in
Tribunals with International Jurisdiction . . . . . . . . . . . . . .
1. Advisory Opinions . . . . . . . . . . . . . . . . . . . . . . . . .
2. Climate Science Informs International Criminal
Court Communication . . . . . . . . . . . . . . . . . . . . .
B. Climate Cases Already Involve Climate Science . . . . . . . . . .
1. United States . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2. The Netherlands . . . . . . . . . . . . . . . . . . . . . . . . . .
3. Germany . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IV. PREPARING THE COURTS: CLIMATE SCIENCE EDUCATION FORJUDGES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
V. CONCLUSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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I. INTRODUCTION
Recent years have seen a growing number of court cases involving
material issues of law, fact, or policy related to climate change.1
Although most cases are filed in U.S. courts, they are also increasingly
being brought before national jurisdictions of other countries andinternational tribunals.2 While international tribunals have not yet
1. See generally Jacqueline Peel & Hari M. Osofsky, Climate Change Litigation, 16 ANN. REV. L. &SOC. SCI. 21 (2020) (reviewing literature involving climate litigation); JOANA SETZER & CATHERINEHIGHAM, GLOBAL TRENDS IN CLIMATE LITIGATION: 2023 SNAPSHOT (2023) (providing overview of
key trends); MICHAEL BURGER & MARIA ANTONIA TIGRE, GLOBAL CLIMATE LITIGATION REPORT:
2023 STATUS REVIEW (2023); Sabrina McCormick et al., Science in Litigation: The Third Branch of
U.S. Climate Policy, 357 SCI. 979 (2017).
2. As of June 2023, the Sabin Center for Climate Change Law reported more than 1,600 casesin the U.S. Climate Change Litigation database and more than 735 cases in the Global Climate
Change Litigation database. These numbers reflect the database’s definition of climate litigation,
which is limited to cases brought before judicial bodies and where climate change law, policy, orscience, is a material issue of law or fact. According to the website, the “database is not exhaustive.
Key limitations include language barriers, levels of media coverage, and public availability ofcourt documents. . . Similarly, the fact that no climate litigation has yet been identified in a given

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seen a significant number of climate cases, the cases that have beenbrought are potentially of high consequence.
The technical details of climate science underpin the legal arguments in several climate cases. Climate science is a diverse field that,among other topics, investigates Earth’s climate system, how it is changing, how these physical changes are impacting human and natural systems, and how much of the change and its consequent impacts can be
attributed to a specific source, sector, or activity. As such, judiciaries
across the world are likely to encounter a growing number of disputesthat require familiarity with the findings and methodologies of climate
science. As with other emerging issues, a prepared judiciary can be a capable judiciary.3 In a survey of judiciaries across the EU, respondents
from Estonia, Spain, Bulgaria, Serbia, and Portugal, emphasized that
more training and specialization related to climate litigation is needed.4
This Article presents some of the challenges and opportunities for thegrowing intersection between science and law in climate litigation andhighlights examples of how climate science has already arisen in climate
litigation.5
II. A REVIEW OF CLIMATE SCIENCE AND WHAT HAPPENS WHEN
IT MEETS THE LAW
Many high-profile climate cases involve scientific evidence that identifies the causes of climate change, its impacts, and its attribution to an
actor, sector, or activity. In this part, we introduce concepts from the science of climate change attribution and compare methods of fact-findingin science and law, highlighting some of the challenges in bridging thetwo disciplines.

jurisdiction should not be taken as a certain indication that no such litigation has been filed or
decided.” About, CLIMATE CHANGE LITIG. DATABASES: SABIN CTR. CLIMATE CHANGE L., http://
climatecasechart.com/about/(last visited July 7, 2023).
3. Joe S. Cecil, Science Education for Federal Judges, AM. BAR ASSOC. (Nov. 1, 2017), https://www.
americanbar.org/groups/judicial/publications/judges_journal/2017/fall/science-educatifederaljudges/(reporting on the importance of Federal Judicial Center science education programming“to ensure that judges are prepared to meet the challenges of a complex and rapidly evolving
culture.”).
4. JOANA SETZER ET AL., CLIMATE LITIGATION IN EUROPE: A SUMMARY REPORT FOR THE EUROPEAN
UNION FORUM OF JUDGES FOR THE ENVIRONMENT 19 (2022), https://www.lse.ac.uk/granthaminstitute/
wp-content/uploads/2022/12/Climate-litigation-in-Europe_A-summary-report-for-the-EU-Forum-ofJudges-for-the-Environment.pdf.
5. The survey of cases presented here is not intended to be comprehensive, but rather toillustrate some of the ways in which climate science has come to bear on the law.

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A. Climate Science and Climate Change Attribution
Progress in climate science has enabled litigation related to mitigation and adaptation around the world. In these climate cases, theIntergovernmental Panel on Climate Change (IPCC) is a common
source of scientific information. Created in 1988, the IPCC assesses thestate of scientific knowledge about climate change and “provide[s] governments at all levels with scientific information that they can use to develop climate policies.”6 As of 2024, the IPCC has representation from
195 member countries. The result of this effort is a regularly published,comprehensive, and authoritative assessment report.7 Because climate
science is an inherently multidisciplinary enterprise, these reports are
written by hundreds of leading climate scientists from around theworld, with different domains of expertise, including geology, atmospheric physics, oceanography, agricultural science, health science, andecology, among others.8 The IPCC separates assessment reports into
three sections, termed “working groups,” that review the full breadth ofscientific evidence around the physical basis of climate change, its
impacts, and possible solutions to the challenges it poses.9 On occasion,
the IPCC also releases “special reports” that investigate specific areas ofinterest, such as the Special Report on Global Warming of 1.5˚C.10
This global and comprehensive assessment of all aspects of the science related to climate change has made the IPCC the world’s leading
authority on climate science. In its 1990 First Assessment Report (FAR),

6. About the IPCC, INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE [IPCC], https://www.ipcc.
ch/about/(last visited June 30, 2023); see also G.A. Res. 43/53, ¶ 5 (Dec. 6, 1988) (writing with“concern[] that certain human activities could change global climate patterns, threatening
present and future generations with potentially severe economic . . . consequences” and “endors[ing] the action of the World Meteorological Organization and the United Nations Environment
Programme in jointly establishing an Intergovernmental Panel on Climate Change to provide
internationally coordinated scientific assessments of the magnitude, timing and potential
environmental and socio-economic impact of climate change and realistic response strategies”).
7. Since publication of the First Assessment Report in 1990, there have been five more. The
latest, the Sixth Assessment Report (“AR6”), was released in 2021 and 2022, with the AR6Synthesis report released in 2023. See IPCC, AR6 SYNTHESIS REPORT: CLIMATE CHANGE 2023 (2023)[hereinafter AR6 SYNTHESIS REPORT], https://www.ipcc.ch/report/ar6/syr/downloads/report/
IPCC_AR6_SYR_FullVolume.pdf.
8. For the information of the authors, see Author, IPCC, https://apps.ipcc.ch/report/
authors/(last accessed Nov. 6, 2023).
9. See About the IPCC, supra note 6.
10. See IPCC, GLOBAL WARMING OF 1.5˚C (2018), https://www.ipcc.ch/site/assets/uploads/
sites/2/2022/06/SR15_Full_Report_HR.pdf; see also IPCC, SPECIAL REPORT ON THE OCEAN AND
CRYOSPHERE IN A CHANGING CLIMATE (2019), https://www.ipcc.ch/site/assets/uploads/sites/3/
2022/03/SROCC_FullReport_FINAL.pdf.

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the IPCC noted that human emissions of heat-trapping greenhouse gasses (GHGs), such as carbon dioxide (CO2), would cause global warming,11 a finding well-supported by individual scientists for the past
several decades.12 Over 30 years later, the IPCC’s Sixth Assessment
Report (AR6) found that “[i]t is unequivocal that human influence has
warmed the atmosphere, ocean and land.”13 The 2021 report continued, “[h]uman-induced climate change is already affecting many
weather and climate extremes in every region across the globe.”14 The
field of attribution science—a field that is also featured in climate litigation—makes such conclusions possible.
As in the law, the attribution of effects to causes is a central issue inclimate science. Attribution science is a multistep exercise in determining the causality that first links emissions to climate change, then links
climate change to climate impacts, such as certain extreme weather
events.15 A scientific consensus has found that global average surface
temperature has risen by about 1.1˚C above pre-industrial levels as of2021 due to human activity, notably from emissions of GHGs associatedwith burning fossil fuels for energy, agriculture, and land-use change.16
This conclusion is based on decades of direct observations of the planet’s
climate system—its lands, waters, ice, atmosphere, and biosphere—andclimate models.17
Climate models are mathematical descriptions of the physical processes that govern the Earth’s climate.18 The late climate scientist andNational Aeronautics and Space Administration (NASA) astronaut
Dr. Piers Sellers said that “[c]limate models are made out of theory . . .

11. IPCC, CLIMATE CHANGE: THE IPCC SCIENTIFIC ASSESSMENT (1990), https://archive.ipcc.
ch/ipccreports/far/wg_I/ipcc_far_wg_I_full_report.pdf.
12. See Spencer Weart, The Discovery of Global Warming [Excerpt], SCI. AM. (Aug. 17, 2012),
https://www.scientificamerican.com/article/discovery-of-global-warming/(excerpting a portionof SPENCER WEART, THE DISCOVERY OF GLOBAL WARMING (Harvard Univ. Press, 2008)).
13. RICHARD P. ALLEN ET AL., SUMMARY FOR POLICYMAKERS 4 (2021), https://report.ipcc.ch/ar6/wg1/IPCC_AR6_WGI_FullReport.pdf.
14. Id. at 8.
15. See Michael Burger et al., The Law and Science of Climate Change Attribution, 45 COLUM. J.
ENV’T L. 57, 66 (2020).
16. AR6 SYNTHESIS REPORT, supra note 7, at 4-5, 42.
17. See generally id., (and accompanying text).
18. See Robert McSweeney & Zeke Hausfather, Q&A: How Do Climate Models Work?, CARBONBRIEF(Jan. 15, 2018), https://www.carbonbrief.org/qa-how-do-climate-models-work/#:�:text¼At%
20their%20most%20basic%20level,covered%20regions%20of%20the%20planet; see also PAUL
HANLE & MICHAEL MASTRANDREA, ENV’T L. INST., CLIMATE SCIENCE AND LAW FOR JUDGES: HOW
CLIMATE SCIENCE WORKS (2023).

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turned into computer code[.]”19 That is, they translate the wellestablished laws of physics into computer code, enabling a skillful
simulation of the state of the climate at a given point in time based onchanges in certain climate variables such as solar output, aerosols, and
GHG emissions, among others.20 Climate models are useful because,
unlike scientists in other disciplines, climate scientists do not have physical replicates of the planet on which to perform experiments.
Modeling allows scientists to run simulated experiments on the world
as-is and on a counterfactual world without human activity, which lets
them answer questions such as, “Did human activity play a role in postindustrial global warming?”21 Based on the simulations from over 100
climate models run by independent research groups that contributed
to the latest IPCC report, the answer to that question is an unequivocal“yes.”22 In fact, the observed warming trend would not be possible but
for the existence of human activity, as natural factors alone would cause
the planet to cool instead of warm.23
Models also allow scientists to interrogate climate-induced changes
in both the severity and probability of certain extreme weather events,
such as coastal flooding, by comparing the world with climate change(as-is) and counterfactual simulations of the world without climatechange.24 By simulating these events under future levels of potential climate change, models can be used to anticipate future climate risks
given various GHG emissions scenarios. The ability to anticipate climate-induced risk raises legal and policy issues, such as questions ofwhat impacts from certain natural disasters are foreseeable in a warmer
world.
In some instances, scientists can take a more granular attribution
approach, linking individual weather events to climate change. This
area of research is termed “event attribution,” which includes extreme
19. Piers Sellers, Space, Climate Change, and the Real Meaning of Theory, NEW YORKER (Aug. 17,2016), https://www.newyorker.com/tech/annals-of-technology/space-climate-change-and-thereal-meaning-of-theory.
20. See Zeke Hausfather et al., Evaluating the Performance of Past Climate Model Projections, 47
GEOPHYSICAL RSCH. LETTERS 1, 1 (2019); see also McSweeney & Hausfather, supra note 18.
21. McSweeney & Hausfather, supra note 18.
22. See AR6 SYNTHESIS REPORT, supra note 7, at v (“confirm[ing] that unsustainable andunequal energy and land use as well as more than a century of burning fossil fuels haveunequivocally caused global warming[.]”) (emphasis added).
23. See Zeke Hausfather, Analysis: Why Scientists Think 100% of Global Warming is Due to Humans,
CARBON BRIEF (Dec. 13, 2017, 4:59 PM), https://www.carbonbrief.org/analysis-why-scientiststhink-100-of-global-warming-is-due-to-humans/#:�:text¼Carbon%20Brief%27s%20analysis%20finds%20that,warming%20than%20has%20actually%20occurred.
24. See Burger et al., supra note 15, at 71.

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event attribution, or the attribution of extreme weather events such as
heatwaves and floods.25 However, individual extreme event attribution
studies might take years to complete, delaying potentially key pieces ofevidence that judges might otherwise rely on to make informed decisions.
To help resolve this timing issue,26 the World Weather Attribution initiative developed a peer-reviewed methodology for more rapid attribution
analyses in the immediate aftermath of, or even during, extreme weather
events.27
Understanding the influence of climate change on extreme weather
events is an important component for assessing the impacts of climatechange on human and natural systems, but it is not the only component. An event attribution study might indicate that a deadly heat wave
was made more likely by climate change, but non-climate variables,such as access to cooling and underlying health conditions, may contribute to the number of deaths caused by that heatwave.28 Such studies
may end up playing critical roles in lawsuits alleging damages related toheatwaves.29 The type of research known as “impact attribution” aims
to isolate the influence of climate change from other factors on theimpact of these events,30 and thus, the research is similarly likely to playa major role in lawsuits that allege damages caused by climate change.
The question of responsibility for climate change and its impacts, as
the final step in the causal chain, is certain to continue to arise in climate litigation. “Source attribution” aims to link the emissions from a

25. Id. at 67 (“discuss[ing] extreme event attribution as a separate category of attribution
research. This is because extreme events do not fit neatly into the ‘climate change attribution’ or‘impact attribution’ categories.”) (emphasis in original).
26. See Lois Parshley, When Disaster Strikes, Is Climate Change to Blame?, SCI. AM. (June 1, 2023),
https://www.scientificamerican.com/article/when-disaster-strikes-is-climate-change-to-blame/(notingthat the World Weather Attribution’s new methodology was primarily meant to address the lag
between a weather event and the results of an attribution study).
27. See Geert Jan van Oldenborgh et al., Pathways and Pitfalls in Extreme Event Attribution, 166
CLIMATIC CHANGE 1, 1 (2021); see also Sjoukje Philip et al., A Protocol for Probabilistic Extreme Event
Attribution Analyses, 6 NATURE ADVANCES STAT. CLIMATOLOGY, METEOROLOGY & OCEANOGRAPHY
177 (2020); WORLD WEATHER ATTRIBUTION, https://www.worldweatherattribution.org/(lastvisited July 14, 2023); see also Parshley, supra note 26 (noting that the work of the World Weather
Attribution was a factor in at least one court decision in Australia).
28. See generally Burger et al., supra note 15, at 88-110 (discussing extreme event attribution,
including extreme heat, drought, heavy precipitation, and tropical and extratropical cyclones).
29. See, e.g., Compl., County of Multnomah v. Exxon Mobil Corp. 4 (Or. Cir. Ct. June 22, 2023)(citing Philip Y. Sjoukje et al., Rapid Attribution Analysis of the Extraordinary Heat Wave on the Pacific
Coast of the US and Canada in June 2021, 13 EARTH SYS. DYNAMICS 1689-1713 (2022)).
30. See Burger et al., supra note 15, at 111-16.

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particular source of GHG emissions to climate change and its impacts.31
A source could be an actor, such as a country or company, a sector,
such as agriculture, or an activity, such as an international flight.32 In
lawsuits against governments and private companies, plaintiffs argue(with varying degrees of success) that these sources should be held accountable for climate-related damages, as discussed below.33 Because
GHGs are well-mixed in the atmosphere, one reasonable method forassessing a source’s contribution to climate change is to calculate thatsource’s proportional emissions relative to total human emissions. Thisapproach will be seen in most of the cases outlined in Part III below.
B. How Climate Science and the Law Collide
Judges and scientists alike weigh evidence and use reason to come totheir conclusions. However, while the law seeks to arrive at a decision
with some degree of finality, those decisions are limited to a certain factual context, while science is an open-ended process that aims to understand the objective reality of the natural world with better precision
over time and, importantly, is unconstrained by court deadlines.34
Judges consider scientific evidence when available and appropriate,but time constraints and a host of other factors make it impossible, andindeed not desirable, for judges to fully investigate the natural world
through the scientific method. As U.S. Supreme Court Justice Stephen
Breyer put it, “[t]he search is not a search for scientific precision. We
cannot hope to investigate all the subtleties that characterize good scientific work.”35 He recognized, though, that “[t]he law must seek decisions
that fall within the boundaries of scientifically sound knowledge.”36
Such an objective is distinct from the scientific one of acquiring knowledge for knowledge’s sake.

31. See, e.g., Richard Heede, Tracing Anthropogenic Carbon Dioxide and Methane Emissions to Fossil
Fuel and Cement Producers, 1854-2010, 122 CLIMATIC CHANGE 229 (2014); Brenda Ekwurzel et al.,The Rise in Global Atmospheric CO2, Surface Temperature, and Sea Level from Emissions Traced to Major
Carbon Producers, 144 CLIMATIC CHANGE 579 (2017); RACHEL LICKER ET AL., UNION OF CONCERNEDSCIENTISTS, TRACING FOSSIL FUEL COMPANIES’ CONTRIBUTION TO CLIMATE CHANGE AND OCEANACIDIFICATION: FACT SHEET (2019), https://www.ucsusa.org/sites/default/files/2019-12/
UCS_acidification_FS_191210a_low-res.pdf.
32. See Burger et al., supra note 15, at 128.
33. See infra Part III.
34. See HANLE & MASTRANDREA, supra note 18, at 2-4.
35. Stephen Breyer, Introduction, in FED. JUDICIAL CTR. & NAT’L RSCH. COUNCIL, REFERENCE
MANUAL ON SCIENTIFIC EVIDENCE 1, 4 (3d ed. 2011).
36. Id.

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Climate scientists and judges also often speak different languages. By
definition, climate is the average of weather over time. As such, findings
in climate science are often discussed in the language of statistics andprobability, which sometimes uses words differently than they are
understood in a non-scientific context.37 For example, the word “uncertainty” in science does not mean “we do not know.” Rather, it is a wordthat describes a full range of possible outcomes that are likely to occur
within a quantifiable upper and lower bound.38
The IPCC has translated the language of statistics into a set of calibrated
likelihood statements that encompass different levels of certainty.39 The
phrase “virtually certain” in IPCC reports indicates that an outcome has a
99-100% probability of being true, and the phrase “extremely likely” indicates a 95-100% probability range.40 To contextualize, the AR6 Synthesis
Report (AR6 SYR), which summarizes the main findings of the three working groups and other IPCC literature, notes, “[i]t is virtually certain that the
global upper ocean (0-700m) has warmed since the 1970s and extremely
likely that human influence is the main driver.”41
IPCC reports are also replete with parenthetical qualitative statements
about the degree of confidence in their findings.42 In general, confidence is said to be highest when there are multiple, independent linesof high-quality evidence that all point in the same direction.43 For example, it was found in the IPCC’s AR6 SYR that “[h]uman-caused climatechange is already affecting many weather and climate extremes in every
region across the globe.”44 Quantitative likelihood statements and qualitative confidence statements together can help judges assess the reliability of claims made about climate change and its impacts. However, these

37. See Astrid Kause et al., Communications about Uncertainty in Scientific Climate-Related Findings:
A Qualitative Systematic Review, 16 ENV’T RSCH. LETTERS 1, 1 (2021) (noting how many of the usersof scientific climate-related findings may lack formal training in climate science or related
disciplines).
38. See generally MICHAEL D. MASTRANDREA ET AL., IPCC, GUIDANCE NOTE FOR LEAD AUTHORS OF
THE IPCC FIFTH ASSESSMENT REPORT ON CONSISTENT TREATMENT OF UNCERTAINTIES (July 6, 2010),
https://www.ipcc.ch/site/assets/uploads/2017/08/AR5_Uncertainty_Guidance_Note.pdf.
39. Id. at 3.
40. Id.
41. AR6 SYNTHESIS REPORT, supra note 7, at 46.
42. See, e.g., MASTRANDREA ET AL., supra note 38, at 1 (noting that “the AR5 will rely on two
metrics for communicating the degree of certainty[,]” and that “[c]onfidence is expressed
qualitatively.”).
43. See id. at 2-3.
44. AR6 SYNTHESIS REPORT, supra note 7, at 42. The report found with high confidence that “[t]his has led to widespread adverse impacts on food and water security, human health and on
economies and society and related losses and damages to nature and people.” Id.

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phrases do not always map comfortably onto legal standards, creating
potential challenges when judges use climate science evidence.45
Judges are also familiar with uncertainty, although that terminology is
not necessarily used in the same way it is in the scientific community.
Various legal standards of proof are, however, framed in terms of certainty. For example, in the United States, the well-known standards forcriminal convictions (“beyond a reasonable doubt”) and most civil cases(“preponderance of the evidence”) demonstrate that the same level ofcertainty is not always required for each dispute, and in fact, it varies
depending on the type of case.46 Although these standards have beenfurther articulated over time,47 absent from them are statements of confidence. For climate science evidence in climate cases, however, issuesof admissibility and reliability have been more relevant. As the cases
described below show, the reliability of consensus climate science has been
repeatedly reinforced by courts, and climate science evidence has been regularly admitted into climate cases.
III. CLIMATE SCIENCE IN COURT CASES
Climate change litigation has accelerated since the early 2000s.48
This part examines the role of science in climate litigation. In tribunals
with international jurisdiction, we focus on one prominent criminal
accusation and several requests for advisory opinions. In addition, thispart outlines some of the most well-known and influential cases fromcourts in the United States, the Netherlands, and Germany.
A. Upcoming Opportunities to Grapple with Climate Science in Tribunals with
International Jurisdiction
Climate cases in courts with international jurisdiction are scarce but
growing. These cases involve attempts at criminal prosecution of government officials and efforts to seek clarity through advisory opinions
on the obligations of states.49 Based on the questions the International

45. See Charles Weiss, Expressing Scientific Uncertainty, 2 L., PROBABILITY & RISK 25, 41 (2003)(comparing various approaches to uncertainty, including legal and IPCC scales).
46. See id. at 31-32 (noting that “several levels of certainty fall within the substantial gap thatlies between the ‘criminal’ and the ‘civil’ standards of proof.”).
47. See id. at 30-32 (describing the narrative language that accompanies each legal standard).
48. SETZER & HIGHAM, supra note 1, at 11 (showing chart with U.S. and non-U.S. cases).
49. The proposal to adopt “ecocide” as a fifth core crime in the Rome Statute has gained
traction lately but is beyond the scope of this paper. See, e.g., Darryl Robinson, Ecocide—Puzzles andPossibilities, 20 J. INT’L CRIM. JUST. 313 (2022) (surveying issues in defining ecocide); see Sabin Ctr.
for Climate Change L., Advisory Opinions on Climate Change: An Overview of a Quartet of Simultaneous

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Court of Justice (ICJ) is currently considering,50 some opinions may
define obligations for states to take climate action under internationallaw and are likely to deal directly with climate science.51 Requested advisory opinions from international tribunals, regardless of their legal
focus, will confront technical evidence that underlies the internationally-recognized scientific consensus on the human-driven causes of climate change and its impacts.52
1.

Advisory Opinions

In late 2022, the Commission of Small Island States on Climate
Change and International Law (COSIS) submitted a request for an advisory opinion to the International Tribunal of the Law of the Sea(ITLOS), in which it asked for clarification of the obligations of stateparties to the United Nations Convention on the Law of the Sea(UNCLOS) with respect to preserving and protecting the marine environment from climate change impacts.53 The provision authorizing the
COSIS to seek an advisory opinion, under the ITLOS’ jurisdiction, explicitly states that climate change is adversely affecting the ocean andimpacting Small Island states.54 Additionally, the COSIS attached to theRequests, YOUTUBE (May 3, 2023), https://www.youtube.com/watch?v¼Fza7UAPsXLI (discussing
advisory opinions from the International Tribunal of the Law of the Sea, the Inter-American
Court of Human Rights, the International Court of Justice, and the African Court of Human andPeoples’ Rights).
50. Obligations of States in Respect of Climate Change, Order, 2023 I.C.J. No. 187, at 2 (Apr.
20), https://www.icj-cij.org/sites/default/files/case-related/187/187-20230420-ORD-01-00-EN.
pdf.
51. See Tiffany Challe-Campiz, Taking Climate Change to the International Court of Justice: Legal andProcedural Issues, COLUM. L. SCH.: CLIMATE L. (Sept. 29, 2021), https://blogs.law.columbia.edu/
climatechange/2021/09/29/taking-climate-change-to-the-international-court-of-justice-legal-andprocedural-issues/(remarking that “[w]e could see an authoritative judicial determination of thevalidity of the science that has been summarized by the IPCC.”).
52. See Sabin Ctr. for Climate Change L., supra note 49.
53. See Request for Advisory Opinion to the International Tribunal for the Law of the Sea [ITLOS]
by Antigua and Barbuda and Tuvalu (Dec. 12, 2022), https://www.itlos.org/fileadmin/itlos/
documents/cases/31/Request_for_Advisory_Opinion_COSIS_12.12.22.pdf [hereinafter Request for
Advisory Opinion to ITLOS by Antigua and Barbuda and Tuvalu]. For overviews and discussions, see
Donald R. Rothwell, Climate Change, Small Island States, and the Law of the Sea: The ITLOS Advisory
Opinion Request, 27 AM. SOC’Y INT’L L. INSIGHTS 1 (May 12, 2023), https://www.asil.org/sites/default/
files/ASIL_Insights_2023_V27_I5.pdf; Maria José Alarcon & Maria Antonia Tigre, Navigating theIntersection of Climate Change and the Law of the Sea: Exploring the ITLOS Advisory Opinion’s Substantive
Content, COLUM. L. SCH.: CLIMATE L. (Apr. 24, 2023), https://blogs.law.columbia.edu/climatechange/
2023/04/24/navigating-the-intersection-of-climate-change-and-the-law-of-the-sea-exploring-the-itlosadvisory-opinions-substantive-content/.
54. Agreement for the Establishment of the Commission of Small Island States on Climate
Change and International Law art. 2(2), Oct. 31, 2021, U.N. Reg. 56940.

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request a dossier of IPCC reports and official statements by COSIS
member states.55
Because the UNCLOS is a technical convention, the ITLOS has experience navigating scientific evidence.56 Due to its familiarity with scientific processes, the ITLOS seems particularly well equipped to assess thescientific evidence that underlies the advisory opinion requested.57 It
could therefore serve as a model for interpreting international law obligations against the scientific background of climate change, and it is,thus, an important finding for other courts to rely upon.58
In early 2023, Chile and Colombia requested an advisory opinion
from the Inter-American Court of Human Rights (IACHR).59 The
55. Dossier Submitted by the Commission of Small Island States on Climate Change and International Law,
ITLOS (Dec. 12, 2022), https://www.itlos.org/en/main/cases/list-of-cases/request-for-an-advisoryopinion-submitted-by-the-commission-of-small-island-states-on-climate-change-and-international-lawrequest-for-advisory-opinion-submitted-to-the-tribunal/dossier-submitted-by-the-commission-ofsmall-island-states-on-climate-change-and-international-law/ (listing documents submitted including
portions of IPCC Working Group I and II reports from AR6).
56. For example, the UNCLOS definition of “pollution of the marine environment” leverages
science to determine which discharges are “likely to result in such deleterious effects as harm toliving resources and marine life, [and] hazards to human health[.]” U.N. Convention on the Lawof the Sea art. 1(1)(4), Dec. 10, 1982, 1833 U.N.T.S. 397 [hereinafter UNCLOS]. To determine
this, the UNCLOS explicitly mentions the need to consider, inter alia, “the best scientific evidence
available,” id. arts. 61, 119, or the “recognized scientific methods,” id. arts. 165, 204. For a
discussion of cases involving the ITLOS’ handling of scientific and technical evidence, see Judge
Jin-Hyun Paik, President, Int’l Tribunal for the L. of the Sea, Keynote Speech on Disputes
Involving Scientific and Technical Matters and ITLOS 3-5 (Aug. 22, 2018) https://www.itlos.org/
fileadmin/itlos/documents/statements_of_president/paik/Iceland_Conference_President_Keynote_
Speech_Final_22August2018.pdf.
57. The precautionary principle may be one way the ITLOS showcases the delicate interplay ofscience and the law. This is a fundamental principle in international environmental law that requires
parties to take precautionary measures to prevent serious environmental harm even when scientificevidence is uncertain or incomplete. The scope of its application is currently unclear, and it remains
to be seen how the ITLOS interprets the precautionary principle regarding States’ obligations ofpreserving and protecting the marine environment, based on IPCC reports that include scientificuncertainties. See Alarcon & Tigre, supra note 53; see also infra notes 153-54 and accompanying text fora discussion of Landgericht Essen [LG] [Regional Court of Essen] Dec. 15, 2016, Aktenzeichen 2 O
285/15, 2016 [hereinafter Lliuya Trial Court Decision].
58. Cf. BRITISH INST. OF INT’L & COMPARATIVE L., PROMOTING CLIMATE JUSTICE THROUGHINTERNATIONAL LAW: CLIMATE LITIGATION & CLIMATE ADVISORY OPINIONS ¶¶ 6, 27 (2023), https://www.biicl.org/documents/163_event_report_climate_advisories_litigation_15_march.pdf (notingthat “[ITLOS] is well-positioned to come up with an authoritative interpretation of [UNCLOS]
obligations” and thus “may deliver pronouncements that the ICJ could build upon[.]”).
59. Request for Advisory Opinion on the Climate Emergency and Human Rights to the InterAmerican Court of Human Rights by the Republic of Colombia and the Republic of Chile (Jan. 9,2023), https://www.corteidh.or.cr/docs/opiniones/soc_1_2023_en.pdf [hereinafter Request for
Advisory Opinion to IACHR by Colombia and Chile].

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request seeks to clarify the obligations of states to respond to the climate emergency within an international human rights framework,
alleging human rights violations caused by climate change.60 This
request frequently cites IPCC reports in addition to individual scientificstudies.61 Here again, the “political and scientific consensus” on the climate emergency is stressed.62
Perhaps most prominently, a Vanuatu-led campaign of numerous
countries, many of which are disproportionately affected by climatechange, is seeking clarity from the ICJ on the legal obligations of stateswith respect to climate change.63 On March 29, 2023, the U.N. General
Assembly (UNGA) adopted a resolution, without a vote, requesting an
ICJ advisory opinion on states’ legal obligations. 64 The Court has
initiated proceedings, setting timelines for comment submissions andresponses.65
Notably, the role of science in advisory opinions can be different
from its role in contentious cases.66 In the latter, the attempt to assign
individual responsibility for climate change to countries would require
proof of causation.67 This hurdle is largely avoided in the ICJ advisory
opinion request context.68 There, the legal question is prefaced bydirectly acknowledging the facts of climate change, referencing IPCC
reports, and expressly noting, for example, “with utmost concern the

60. See also Maria Antonia Tigre et al., A Request for an Advisory Opinion at the Inter-American Courtof Human Rights: Initial Reactions, COLUM. L. SCH.: CLIMATE L. (Feb. 17, 2023), https://blogs.law.
columbia.edu/climatechange/2023/02/17/a-request-for-an-advisory-opinion-at-the-inter-americancourt-of-human-rights-initial-reactions/.
61. See generally Request for Advisory Opinion to IACHR by Colombia and Chile, supra note 59.
62. Id.
63. Vanuatu lists the core group of nations as Antigua & Barbuda, Costa Rica, Sierra Leone,
Angola, Germany, Mozambique, Liechtenstein, Samoa, Federated States of Micronesia,
Bangladesh, Morocco, Singapore, Uganda, New Zealand, Vietnam, Romania and Portugal. The
Republic of Vanuatu is Leading the Initiative at the UN International Court of Justice for an Advisory
Opinion on the Obligations of States Relevant to Climate Action, VANUATU ICJ INITIATIVE, https://www.
vanuatuicj.com/(last visited July 7, 2023).
64. G.A. Res. 77/276, at 3 (Mar. 29, 2023).
65. See Obligations of States in Respect of Climate Change, supra note 50, at 2 (fixing Oct. 20,
2023, as the date for submission of written statements on the presented questions, and Jan. 22,
2024, as the deadline for responses to those comments).
66. Contentious jurisdiction is exercised over legal disputes between two or more States. It
entails certain procedural hurdles and applicability limitations and can only be exercised overStates that have accepted jurisdiction of the ICJ in these cases, which the world’s largest emittersof GHG, China and the United States, have not. See Challe-Campiz, supra note 51.
67. Id.
68. Id.

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scientific consensus . . . that anthropogenic emissions of greenhousegases are unequivocally the dominant cause of the global warming.”69
How might scientific evidence come before ICJ judges? The admission of scientific experts to testify directly before the ICJ and to be
cross-examined by the parties is historically rare. The ICJ first allowed
this in the 2014 Japanese whaling case.70 In the request for an advisory
opinion, however, none of the state representatives doubted climatechange or downplayed the importance of addressing climate issues, so
scientific matters were uncontested.71 If states were to substantiallyquestion the foundations of climate science and climate change, or if
the ICJ itself considered anthropogenic climate change not to be a universal consensus, then scholars anticipate that scientific experts might
have the opportunity to testify before the Court.72 In addition, if more
specific questions related to attribution science and responsibility wereposed, it is possible that this would elicit science-based testimony.
2.

Climate Science Informs International Criminal Court
Communication

In addition to these advisory opinions, AllRise—a litigation-focused
non-profit—filed a communication on October 12, 2021, calling forinvestigation and prosecution by the International Criminal Court (ICC)
for alleged crimes against humanity committed by former Brazilian
President Jair Bolsonaro and members of his Administration.73 The communication includes two interrelated allegations. First, it alleged thatPresident Bolsonaro and his Administration have “knowingly facilitatedand promoted” widespread attacks upon the Amazon Biome and “those
69. G.A. Res. 77/276, supra note 64, at 2 (emphasis in original).
70. See generally Whaling in the Antarctic (Austl. v. Japan: N.Z. Intervening), Judgment, 2014 I.
C.J. Rep. 226 (Mar. 31); see also Challe-Campiz, supra note 51.
71. See Press Release, General Assembly, General Assembly Adopts Resolution Requesting
International Court of Justice Provide Advisory Opinion on States’ Obligations Concerning
Climate Change, U.N. Press Release GA/12497 (Mar. 29, 2023).
72. Maria Antonia Tigre & Jorge Alejandro Carrillo Banuelos, The ICJ’s Advisory Opinion on
Climate Change: What Happens Now?, COLUM. L. SCH.: CLIMATE L. (Mar. 29, 2023), https://blogs.law.
columbia.edu/climatechange/2023/03/29/the-icjs-advisory-opinion-on-climate-change-whathappens-now/.
73. ALLRISE, COMMUNICATION UNDER ARTICLE 15 OF THE ROME STATUTE OF THE INTERNATIONAL
CRIMINAL COURT (2021), https://climatecasechart.com/wp-content/uploads/non-us-casedocuments/2021/20211012_14633_na.pdf. Before this filing, activist groups had framed
Bolsonaro’s acts as “ecocide,” according to the definition worked out by the Stop Ecocide
Foundation. See, e.g., Ernesto Londo~
no, Imagine Jair Bolsonaro Standing Trial for Ecocide at theHague, N.Y. TIMES (Sept. 21, 2019), https://www.nytimes.com/2019/09/21/sunday-review/
bolsonaro-amazon-fire.html; see also Robinson, supra note 49.

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who defend and depend on it,” referred to as “Environmental
Dependents and Defenders.”74 Second, the communication claimed that
Bolsonaro and his Administration have created a “clear and extant threat
to humanity itself” through the Amazon’s deforestation,75 with disastrous
consequences for the global climate, which allegedly has resulted and willcontinue to result in loss of life and “physical and mental suffering.”76
Notably, the communication incorporates and frequently cites anearly 100-page expert report specifically prepared for this filing on
global climate change impacts attributable to deforestation of the
Amazon.77 The report follows the steps of climate change attribution
science outlined above, attributing deforestation promoted and aggravated by President Bolsonaro and his Administration to the increased
emission of GHGs and the exacerbation of climate change.78 The
report attempts to provide scientific evidence to support the allegationthat Bolsonaro’s deforestation practices created a long-term global
impact on climate change that is not easily reversed.79
The advisory opinion examples cited above, along with the ICJ communication, demonstrate that climate-related actions in international
tribunals are increasing. Courts are being asked to articulate how climate change, and specifically climate science, fit into international law
regimes and obligations, whether that is within the scope of a specificframework, such as under UNCLOS (e.g., the COSIS request), or
within international law more broadly (e.g., the Vanuatu-led request).
Regardless of the outcome of these cases, international tribunals will

74. ALLRISE, supra note 73, ¶¶ 1, 14. Even though every human being “depends” on a stableglobal climate and an intact Amazon rainforest, it appears by “Environmental Dependents andDefenders,” AllRise only means the local populations living in and off the Amazon and defending
it locally against deforestation attempts. These local communities allegedly suffer(ed)persecution, humiliation, armed invasion, murder and other forms of inhumane acts, committed
by President Bolsonaro and his Administration. Id. ¶ 14.
75. Id. ¶ 1.
76. Id. ¶¶ 35-39.
77. Id. ¶ 69 (citing RUPERT F. STUART-SMITH ET AL., GLOBAL CLIMATE CHANGE IMPACTSATTRIBUTABLE TO DEFORESTATION DRIVEN BY THE BOLSONARO ADMINISTRATION: EXPERT REPORTFOR SUBMISSION TO THE INTERNATIONAL CRIMINAL COURT 15 (2021), https://www.smithschool.ox.
ac.uk/sites/default/files/2022-03/ICC_report_final-sept-2021.pdf).
78. See RUPERT F. STUART-SMITH ET AL., GLOBAL CLIMATE CHANGE IMPACTS ATTRIBUTABLE TO
DEFORESTATION DRIVEN BY THE BOLSONARO ADMINISTRATION: EXPERT REPORT FOR SUBMISSION TO
THE INTERNATIONAL CRIMINAL COURT 21 (2021).
79. ALLRISE, supra note 73, ¶¶ 230-34, 237. Cited impacts include extreme weather events,
deadly heat waves, droughts and wildfires, changes in rainfall patterns leading to floods anddroughts, and sea level rise. Id.

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assuredly continue to confront climate-related content as climate scienceadvances and climate impacts become more severe and widespread.
B. Climate Cases Already Involve Climate Science
Climate science has played a central role in cases before domestic
courts. Their treatment provides insight into how other courts, and particularly international tribunals, may respond to climate science evidence. This section highlights a few notable examples from the UnitedStates, the Netherlands, and Germany.
1.

United States

In the United States, judges in state and federal courts—including
the U.S. Supreme Court—have ruled on cases related to climatechange.80 Climate change has also figured prominently in the filings ofhigh-profile rights-based cases brought on behalf of youth plaintiffs by
the non-profit Our Children’s Trust (OCT).81 Climate science was frontand center in Massachusetts v. EPA, where the U.S. Supreme Court
examined a challenge by the Commonwealth of Massachusetts against
the U.S. Environmental Protection Agency (EPA) for denying a petition to regulate GHG emissions from new motor vehicles.82 JusticeJohn Paul Stevens, writing for the Court, found aspects of climate science critical in determining that the Commonwealth had standing tobring the case.83 While the Commonwealth was given “special solicitude” because of its “stake in protecting its quasi-sovereign interests,”84
the Court relied on declarations from climate scientists, including
80. The most common climate litigation in the United States involves claims pursuant to the
National Environmental Policy Act and the Endangered Species Act. Both frequently involve
climate science. See, e.g., JESSICA WENTZ, ENV’T L. INST., CLIMATE SCIENCE AND LAW FOR JUDGES:GOVERNMENT ACTION AND CLIMATE SCIENCE 7-8, 19-25 (2023).
81. See, e.g., Complaint at 3-4, Reynolds v. State of Florida, No. 37 2018 CA 000819 (Fla. Cir. Ct.
Apr. 16, 2018); Complaint at 3-4, Sinnok v. State of Alaska, No. 3AN-17-09910 (Alaska Super. Ct.
Oct. 27, 2017); Complaint at 2-4, Aji P. v. State of Washington, No. 18-2-04448-1 SEA (Wash.
Super. Ct. Feb. 16, 2018); Complaint at 1-4, Held v. Montana, No. CDV-2020-307 (Mont. Dist. Ct.
Mar. 13, 2020).
82. See Massachusetts v. EPA, 549 U.S. 497, 521-28 (2007).
83. See id. at 521-26. In U.S. federal courts, establishing Article III standing requires a plaintiff
demonstrate three elements: (1) an actual or imminent injury, (2) that the injury is caused (or is“fairly traceable”) to the defendant, and (3) that a favorable decision from the court will likely
redress the injury. Id. at 517.
84. Id. at 520. But see United States v. Texas, No. 22-58, slip op. at 13, n.6 (June 23, 2023)(rejecting on standing grounds a challenge brought by Texas and Louisiana against the UnitedStates related to immigration enforcement and stating that although the states relied on
Massachusetts v. EPA, “that decision does not control this case” as it related to the denial of a578[Vol. 54

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Doctors Michael MacCracken and Michael Oppenheimer and others,
as well as reports from the IPCC to conclude that Massachusetts had
standing.85
When examining the injury required for standing, Justice Stevens
quoted directly from Dr. MacCracken’s declaration:[Q]ualified scientific experts involved in climate change
research” have reached a “strong consensus” that global warming threatens (among other things) a precipitate rise in sea levels by the end of the century, “severe and irreversible changes
to natural ecosystems,” a “significant reduction in water storage
in winter snowpack in mountainous regions with direct and important economic consequences,” and an increase in the spreadof disease[.]86
Justice Stevens called attention to two points. First, that Dr. MacCracken’s
declaration speaks to a field of qualified experts, and second, thatthe experts have reached a “strong consensus.” 87 On causation,
Stevens confirmed that the basic tenets of climate science were notcontested in the case. 88 In response to EPA’s argument that emissions were not significant enough to cause the injury, the Court
found that the U.S. transportation sector accounted for more thansix percent of CO 2 emissions worldwide, 89 and as such, they “makea meaningful contribution to . . . global warming.”90 Thus, accounting
for GHG emissions, or showing how much emissions can be attributed

rulemaking petition, whereas United States v. Texas was a challenge of the Executive Branch’s
enforcement discretion).
85. See Massachusetts v. EPA, 549 U.S. at 508-11, 521-25. MacCracken was an instrumental
figure in the establishment of the U.S. Global Change Research Program (USGCRP). The
USGCRP was created by congressional act in 1990 and is responsible for coordinating efforts of
13 agencies to produce a quadrennial National Climate Assessment to “understand, assess,predict, and respond to human-induced and natural processes of global change.” See 1 U.S. Glob.
Change Rsch. Program [USGCRP], CLIMATE SCIENCE SPECIAL REPORT: FOURTH NATIONAL
CLIMATE ASSESSMENT 1 (2017); see also 2 USGCRP, CLIMATE SCIENCE SPECIAL REPORT: FOURTHNATIONAL CLIMATE ASSESSMENT (2018); Global Change Research Act of 1990, § 101(b). The Fifth
National Climate Assessment was released in November of 2023.
86. Massachusetts v. EPA, 549 U.S. at 521 (internal citations omitted).
87. Id.
88. See id. at 523 (“EPA does not dispute the existence of a causal connection between
manmade greenhouse gas emissions and global warming.”).
89. Id. at 524 (relying on declarations from another climate scientist, Michael Oppenheimer).
90. Id. at 525.

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to a particular entity or source (i.e., source attribution), was a factor in
the determination.91
Since Massachusetts v. EPA, plaintiffs have continued to put forward
climate science evidence to advance their claims, including in casesthat involve rights to a healthy and/or stable climate.92 Many cases
allege that government policies supporting fossil fuels have violated aconstitutional right to a healthy and/or stable climate.93 In Juliana v.
United States, a federal court in Oregon found that there is “no doubtthat the right to a climate system capable of sustaining human life isfundamental to a free and ordered society . . . a stable climate system isquite literally the foundation ‘of society, without which there would beneither civilization nor progress.’”94 In reaching this conclusion, however, the judge reinforced that “[t]his lawsuit is not about proving thatclimate change is happening or that human activity is driving it . . .
those facts are undisputed.”95 Writing at the motion to dismiss stage,
and therefore taking the plaintiffs’ factual allegations as true, the opinion frequently cites to the climate science underpinning the plaintiffs’
complaint.96 The citations include references to accounting for theamount of GHG emissions resulting from various activities, such as leasing for oil, gas, and coal production.97
While Juliana has not yet seen an opinion on the merits,98 despite
two trips to the U.S. Supreme Court,99 a divided panel of U.S. Court of
91. For other discussions of “meaningful contribution,” see Wash. Env’t Council v. Bellon, 732
F.3d 1131, 1145-46 (9th Cir. 2013), reh’g en banc denied, 741 F.3d 1075 (9th Cir. 2014) (finding that
GHG emissions from Washington oil refineries, which “mak[e] up 5.9% of emissions in
Washington,” are not “‘meaningful contribution’ to global GHG levels.”; see also Amigos Bravos
v. U.S. Bureau of Land Mgmt., 816 F. Supp. 2d 1118, 1136 (D.N.M. 2011) (“the potential 254,730
metric tons of GHGs per year that might result from the approval of 92 oil and gas leases [were]
not a particularly meaningful contribution to global emissions.”) (emphasis added).
92. See, e.g., Complaint at 20-44, Reynolds, No. 37 2018 CA 000819; Complaint at 45-67,
Sinnok, No. 3AN-17-09910; Complaint at 24-41, Aji P., No. 18-2-04448-1 SEA; Complaint at 17-26,
Held, No. CDV-2020-307.
93. See 2023 Mid-Year Review, OUR CHILDREN’S TRUST: YOUTH V. GOV., https://www.
ourchildrenstrust.org/midyear-review-2023(last visited June 27, 2023).
94. Juliana v. United States, 217 F. Supp. 3d 1224, 1250 (D. Or. 2016) (internal citation omitted).
95. Id. at 1234.
96. See id. at 1245-46.
97. See id. at 1246.
98. After the U.S. Court of Appeals for the Ninth Circuit dismissed the case on standing
grounds, see Juliana v. United States, 947 F.3d 1159 (9th Cir. 2020), Judge Aiken granted
plaintiff’s request to file an amended complaint, see Juliana v. United States, No. 6:15-CV-01517AA, 2023 WL 3750334 (D. Or. June 1, 2023). As of this writing, the case is ongoing.
99. For a discussion of the Court’s use of the shadow docket, including in this case, see Robert
V. Percial, The Shadow Docket, THE ENV’T FORUM (Jan./Feb. 2022); see also Richard J. Pierce, Jr.,

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Appeals judges for the Ninth Circuit took notice of the role of climate
science in their 2020 opinion.100 Although ultimately dismissing thecase under the theory that injunctive relief would not redress the plaintiffs’ alleged injuries,101 the majority nevertheless concluded that theplaintiffs satisfied the injury and causation prongs of the standing analysis.102 On injury, the majority concluded that injuries related to domestic displacement from water scarcity and flooding provided sufficient“evidence that climate change is affecting them now in concrete ways
and will continue to do so unless checked.”103 In her dissenting opinion, Judge Josephine Staton,104 remarking on the important role playedby climate science, concluded with an emphatic note that the “[p]laintiffs’ claims are based on science, specifically, an impending point of no
return.”105
Montana’s First District Court was the first court to hold a trial on the
merits and issue a decision in an OTC case.106 The case involved a challenge to an exception to the Montana Environmental Policy Act(MEPA), barring state agencies from considering climate change,
including for fossil fuel development.107 The plaintiffs, a group ofMontana youth led by Rikki Held, sought a declaratory judgment that
the MEPA provision violated Montana’s Constitution, which provides aright to a “clean and healthful environment.”108
At trial, however, it was clear that not all parties were familiar withthese foundational climate science sources. For example, the directorof Montana’s Department of Environmental Quality suggested that,prior to trial, he was not aware of the decades of increasingly dire
The Supreme Court Should Eliminate Its Lawless Shadow Docket, 74 ADMIN. L. REV. 1 (2022) (using the
U.S. Environmental Protection Agency’s Clean Power Plan as an illustrative case).
100. See Juliana, 947 F.3d at 1166 (referencing plaintiffs’ “[c]opious expert evidence” onclimate change causes and impacts).
101. See id. at 1171 (finding that the redressability prong is not satisfied because “it is beyond
the power of an Article III court to order, design, supervise, or implement the plaintiffs’
requested remedial plan.”).
102. See id. at 1168-69.
103. Id. at 1168.
104. Id. at 1160, 1164 (Judge Staton, U.S. District Judge for the Central District of California,
sat by designation).
105. Id. at 1191.
106. See Held v. State of Montana, No. CDV-2020-307 (Mont. Dist. Ct. Aug. 14, 2023). As of thiswriting, the case is currently on appeal before the Montana Supreme Court.
107. See id. at 15-17.
108. See id. at 1-2. The Montana Constitution provides that “[a]ll persons are born free andhave certain inalienable rights. They include the right to a clean and healthful environment[.]”MONT. CONST., art. II, § 3. And that “[t]he state and each person shall maintain and improve aclean and healthful environment in Montana for present and future generations.” Id., art. IX, § 1.

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reports from the IPCC.109 Moreover, one of Montana’s attorneys, incross-examining paleoclimatologist Dr. Cathy Whitlock, mischaracterized the IPCC, referring to the intergovernmental body as the “ICP”
and became seemingly confused with respect to the various acronyms
involved in the IPCC reports.110
On August 11, 2023, Judge Seeley issued an opinion that included
fact-finding statements replete with references to climate science fromthe plaintiff’s experts,111 including Dr. Steven Running, Dr. Cathy
Whitlock, and Peter Erickson, among others.112 These experts presented testimony based on various reports, including those from the
IPCC and Montana’s state climate assessment.113 Judge Seeley concluded that Montanans are experiencing the impacts of climatechange,114 and those impacts are projected to worsen “if the State continues ignoring GHG emissions and climate change[,]”115 and Montana’semissions are contributing to increases in GHG emissions worldwide.116
The Court found that testimony from Dr. Terry Anderson, the defendants’ expert economist, “was not well-supported, contained errors, andwas not given weight by the Court.”117
2.

The Netherlands

Two other well-known domestic climate cases are Urgenda Foundationv. State of the Netherlands and Milieudefensie v. Royal Dutch Shell plc, which
are both from the Netherlands and rely on climate science related
to ongoing and projected sea-level rise and other climate impacts

109. Lesley Clark, 5 Takeaways From Historic Montana Climate Trial, CLIMATEWIRE (June 23,2023), https://subscriber.politicopro.com/article/eenews/2023/06/23/5-takeaways-from-montanashistoric-climate-trial-00103130.
110. Id. (reporting that the attorney for Montana “[t]here’s a lot of C’s and P’s involved inthis” when discussing shared socioeconomic pathways, or SSPs, and representative concentration
pathways, or RCPs).
111. Held, No. CDV-2020-307 at 19, 23-25, 35, 38 (“There is overwhelming scientific consensus
that Earth is warming as a direct result of human GHG emissions, primarily from the burning offossil fuels.”).
112. Id. at 17-19; for the list of the experts and the summary of their arguments, see Jarryd
Page, Climate Science on the Docket: How Held v. Montana is Bridging Science and Law, ENV’T L. INST.:
Vibrant Env’t Blog (Aug. 11, 2023), https://www.eli.org/vibrant-environment-blog/climatescience-docket-how-held-v-montana-bridging-science-and-law.
113. See Held, No. CDV-2020-307 at 17-19.
114. See id. at 35-46.
115. Id. at 46.
116. Id. at 70 (“What happens in Montana has a real impact on fossil fuel energy systems, CO2
emissions, and global warming.”).
117. Id. at 66.

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findings.118 In Urgenda, the challengers—Dutch citizens and a Dutch
environmental group—sought to advance climate action by the Dutch
government.119 In 2018, the Dutch Appellate Court agreed with thelower court, finding the Dutch government was not doing enough toaddress climate change and ordering (in a global first) the government
to reduce emissions to twenty-five percent below 1990 levels by 2020.120
In reaching this conclusion, the Court referred to the fourth and fifth
IPCC assessment reports extensively, cited NASA data on historicalwarming, and noted projections of emissions from the European
Database for Global Atmospheric Research.121 The decision was affirmedby the Dutch Supreme Court.122
Similarly, in Milieudefensie, the Court found that Royal Dutch Shell(Shell) was not doing enough to reduce emissions in light of the Paris
Agreement and scientific consensus about climate change and its
impacts, thus violating the duty of care under Dutch law, and ordered
the corporation to reduce emissions to forty-five percent below 2019
levels by 2030.123 This first-ever decision by a judge to require a privatecompany to reduce emissions also relied on findings from IPCC
reports124 and analysis of legal protections, as articulated in Urgenda.125
Climate science provided crucial support for the decision, as theMilieudefensie opinion cited IPCC’s Fifth Assessment Report (AR5) andthe 1.5˚C Special Report, material from the Royal Netherlands
Meteorological Institute and the International Energy Agency, reports
from the European Environment Agency, as well as studies from
118. Hof’s-Gravenhage 9 oktober 2018, AB 2018, 417 m.nt. GA van der Veen, Ch.W. Backes(Staat der Nederlanden/Stichting) (Neth.) [hereinafter Urgenda Court of Appeal Opinion];
Hof’s-Gravenhage May 26, 2021, JOR 2021/208 m.nt. Biesmans, SJM (Vereeniging Milieudefensie/
Royal Dutch Shell PLC) (Neth.) [hereinafter Milieudefensie].
119. For a brief description of the case, see Urgenda Foundation v. State of the Netherlands, SABIN
CTR. FOR CLIMATE CHANGE L., https://climatecasechart.com/non-us-case/urgenda-foundation-vkingdom-of-the-netherlands/(last visited Aug. 18, 2023).
120. Id.
121. See Urgenda Court of Appeal Opinion, supra note 118, ¶¶ 12, 44.
122. HR Dec. 20, 2019, JM 2020/33 m.nt. Douma, W.Th. (De Staat Der Nederlanden/
Stichting Urgenda).
123. Milieudefensie, JOR 2021/208, ¶ 3.1.1; see Stanley Reed & Claire Moses, A Dutch Court
Rules That Shell Must Step Up Its Climate Change Efforts, N.Y. TIMES (updated Oct. 28, 2021), https://www.nytimes.com/2021/05/26/business/royal-dutch-shell-climate-change.html. The case is currently
on appeal in Dutch court.
124. Milieudefensie, JOR 2021/208, ¶ 2.3.5 (“[t]he global consequences of climate change
are apparent from the reports of the Intergovernmental Panel on Climate Change”).
125. Id. ¶ 4.4.10 (“It can be deduced from the Urgenda judgment that Articles 2 and 8 of the[European Convention on Human Rights] provide protection against the consequences ofdangerous climate change as a result of global warming due to Co2 emissions”).

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Deltares, a Dutch research non-profit organization, on the impacts ofaccelerated sea-level rise on the Dutch Delta Programme and tidal
basins.126 Shell challenged the plaintiff’s characterization of some
aspects of climate science, arguing that the plaintiff Milieudefensie misrepresented the scientific sources as they relate to “tipping points,” elements of the climate system that are hard to reverse upon reachingsome threshold,127 in addition to mitigation and adaptation.128 Shellalso argued that the impacts of “heat stress” and sea-level rise on the
Dutch people were misrepresented.129 Notably, however, the authorityof the IPCC and the integrity of its climate science was not a centrally
contested issue.130 Shell’s contribution to climate change through its
GHG emissions was similarly not in dispute.131 That this aspect went
unchallenged is perhaps not surprising given Shell’s historical andglobal position in the energy market; though, questions of source attribution may arise for corporations that do not have the same quantity ofhistorical and/or annual emissions. In fact, this was a point of contention in Lliuya v. RWE AG, discussed below.
3.

Germany

Under German jurisdiction, courts have been called to help mitigate
climate change or deal with its consequences. In 2021, youth plaintiffs
in Neubauer v. Germany received a major victory before Germany’s highest court, the Federal Constitutional Court.132 The Higher Regional

126. See id. ¶¶ 2.3.5-2.3.9. The Delta Programme develops “plans to protect the country fromflooding, mitigate the impact of extreme weather events, and secure supplies of freshwater.” Delta
Programme: Flood Safety, Freshwater, and Spatial Adaptation, GOV’T OF THE NETH., https://www.
government.nl/topics/delta-programme/delta-programme-flood-safety-freshwater-and-spatialadaptation (last visited July 13, 2023).
127. Pleading Notes: Science, Milieudefensie et al. v. Royal Dutch Shell PLC, Case No. C/09/
571932 19/379 6-16 (Hof’s-Gravenhage), ¶¶ 16-17.
128. See id. ¶¶ 26-27.
129. See id. ¶¶ 32-40.
130. Id. ¶ 11 (remarking that “[t]he IPCC Assessment Reports are of particular importance”
and focusing on how Milieudefensie characterized the science, not on the IPCC’s credibility or
output, which is described by Shell as having been “drafted very extensively and with the utmost
care and precision.”).
131. Milieudefensie, JOR 2021/208, ¶ 4.4.5. (stating that” [i]t is not in dispute that these
global CO2 emissions of the Shell group (Scope 1 through to 3) in the Netherlands and the
Wadden area contribute to [global] warming and climate change.”).
132. See generally BVerfG, Order of the First Senate of 24 March 2021, 1 BvR 2656/18,
https://www.bundesverfassungsgericht.de/SharedDocs/Entscheidungen/EN/2021/03/
rs20210324_1bvr265618en.html [hereinafter Neubauer].

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Court of Hamm is currently collecting scientific evidence in Lliuya, atort case against Europe’s largest single emitter of GHGs.133
In Neubauer, the Court unanimously decided that the Federal
Climate Change Act, the country’s framework climate legislation that
included a GHG emissions reduction mandate, was not strict enough toadequately protect the complainants’ fundamental rights as articulated
in Germany’s Constitution.134 Because the state has a duty to protectthese rights over time, the Court ruled that the German legislaturemust provide a clear pathway to reduce the country’s CO2 emissions
more rapidly.135
The Court dedicated significant space to explaining the greenhouseeffect, its relationship to climate change, and various climate protection
measures.136 Like other cases, it relied heavily on IPCC reports, which
the opinion describes as reliable sources of current scientific knowledge on climate change. A portion of the opinion is devoted to explaining the IPCC, its history, mandate, and the multi-step process forestablishing its virtually worldwide scientific consensus.137 The Court
also referenced reports by German executive agencies.138 These sources133. See Luciano Lliuya v. RWE AG, CLIMATE CHANGE LITIGATION DATABASES, https://climatecasechart.
com/non-us-case/lliuya-v-rwe-ag/#:�:text¼The%20court%20noted%20that%20it,relationship%20between%20particular%20greenhouse%20gas, for the court docket. A counterexample isa case filed by organic farmers and Greenpeace in the Administrative Court of Berlin against
the Federal government for not complying with its own climate protection goal. The court
dismissed the case because the plaintiffs failed to provide scientific evidence to prove standing.
See Administrative Court of Berlin, Judgment of the 10. Chamber of October 31, 2019, filed
under 10 K 412.18 (finding that an emissions reduction of 32% below 1990 levels instead of theenvisioned 40% by 2020 did not suffice to threaten plaintiffs’ fundamental rights to property,
life, and profession imminently); see also Markus Sehl, Bio-Bauern Scheitern Mit “Klimaklage”,
LEGAL TRIB. ONLINE (Oct. 31, 2019), https://www.lto.de/recht/hintergruende/h/vg-berlin-10k-412-18-klima-klage-umweltschutz-bauern-greenpeace-bundesregierung/.
134. See Neubauer, BvR 2656/18, ¶ 117. Germany’s Constitution is referred to domestically as
the Basic Law (Grundgesetz). Interestingly, and unusually, the court did not put an emphasis onwhich fundamental right was violated, but rather took all fundamental freedoms together. See id.
¶¶ 142, 183.
135. See id. at headnote 5.
136. See id. ¶¶ 16-31.
137. That process requires contributing scientists to first reach an agreement before theirfindings can be reviewed by independent external experts; only then can they be adopted bypolicymakers of the member states (whose changes to the reports in turn are controlled again by
the scientists). See id. ¶¶ 16-17 (citing to IPCC, Guidance Note for Lead Authors of the IPCC Fifth
Assessment Report on Consistent Treatment of Uncertainties (2010); IPCC, Procedures for the Preparation,
Review, Acceptance, Adoption, Approval and Publication of IPCC reports (2013)); see also Preparing
Reports, IPCC, https://www.ipcc.ch/about/preparingreports/(last visited July 14, 2023).
138. These include the Federal Ministry for the Environment, Natural Conservation
and Nuclear Safety, the German Environment Agency, the German Advisory Council on the

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were used, inter alia, to prove that Germany is historically responsiblefor 4.6% of all anthropogenic GHG emissions (or currently two percent
annually), and that Germany’s per-capita GHG emissions exceed theglobal median by 100%.139
Because of the almost-linear correlation between the increase inatmospheric CO2 concentration and global warming, the Court explained,a specific GHG reduction obligation can be derived from the Paris
Agreement’s temperature target.140 Still, due to the complexity of theclimate system, uncertainties regarding the remaining CO2 budget
persist.141 The Court addressed these uncertainties explicitly, notingthat scientific uncertainties cannot justify legislative arbitrariness insetting CO2 emissions reduction goals.142 The lack of otherwise available, reliable scientific data, and the fact that the IPCC’s calculations
still provide the best estimate of the remaining CO2 budget, forced
the legislature to respond to indicators of irreversible damage.143 The
Court moreover cited Article 3 of the U.N. Framework Convention
on Climate Change,144 which provides that “[w]here there are threatsof serious or irreversible damage, lack of full scientific certainty should
not be used as a reason for postponing [precautionary] measures.”145
In Lliuya, attribution science is at the core of the dispute.146 The
plaintiff, Saúl Luciano Lliuya, a Peruvian mountain guide and farmer,
sued Europe’s largest individual emitter of GHGs and one of Germany’s

Environment (SRU), and the German Meteorological Service, among others. Neubauer, BvR
2656/18, ¶ 16.
139. See id. ¶¶ 29-30.
140. See id. ¶¶ 216 et seq.
141. The IPCC and the SRU have indicated that specific correlations between cumulated
emissions and global warming cannot be fully verified. See id. ¶¶ 222, 224-27.
142. See id. ¶ 220.
143. See id. ¶ 223. Regarding the SRU, the Court finds that it has determined the remaining
CO2 budget for Germany “using verifiable figures and sound calculation methods [and] based on
the IPCC’s scientifically justified assumptions[.]” See id. ¶ 220 (internal citation omitted) (nonauthoritative translation provided by the Court itself). Therefore, it can be relied upon.
144. See id. ¶ 229.
145. United Nations Framework Convention on Climate Change art. 3(3), May 9, 1992, S.
Treaty Doc. No. 120-38, 1771 U.N.T.S. 107 (noting that this approach should be “taking into
account that policies and measures to deal with climate change should be cost-effective so as toensure global benefits at the lowest possible cost.”).
146. See Luciano Lliuya v. RWE AG, supra note 133. According to the plaintiff and his campaign
support groups, this is the first case worldwide to enforce corporate liability for climate changethat entered the evidentiary stage. See Legal: A Precedent-Setting Case, THE CLIMATE CASE: SAUL V.
RWE, https://rwe.climatecase.org/en/legal (last visited July 14, 2023).

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biggest utility companies, RWE AG.147 Lliuya argued, using a 2021 study
led by Dr. Rupert Stuart-Smith, that the emissions from RWE facilities
are contributing to climate change and melting a glacier located near
the plaintiff’s property.148 Lliuya further argued that glacial melt caused
an increase in an adjacent glacial lake’s water volume, which threatens
to burst the dams and cause damage to his property.149 As a remedy,
Lliuya sought money damages sufficient to install protective measuresagainst an imminent glacial lake outburst flood (GLOF).150 The claim
amounts to 0.47% of the cost of these adaptive measures (17,000e), a
number taken directly from the 0.47% of global emissions for which
RWE was allegedly responsible.151
At trial, the plaintiff introduced several scientific studies and expert
witnesses to prove that climate change and the melting glacier threatening the plaintiff’s property were caused partly by RWE’s emissions.152
The Court dismissed the claim, finding that scientific causation does
not amount to legal causation under German law.153 According to the
Court, even though the scientific evidence shows that all GHG emissions contribute to climate change, individual emissions could not be
attributed to a single source because of the plethora of different
sources.154

147. Peruvian Farmer Sues German Utility RWE over Dangers Related to Glacial Melting, THE CLIMATE
CASE: SAUL V. RWE, https://rwe.climatecase.org/en/presse/article/peruvian-farmer-sues-germanutility-rwe-over-dangers-related-glacial-melting (last visited Oct. 25, 2023).
148. Id. One 2021 study found that “it is virtually certain (>99% probability) that the retreat ofPalcaraju glacier to the present day cannot be explained by natural variability alone . . . central
estimate is that the overall retreat is entirely attributable to the observed temperature trend, andthat the resulting change in the geometry of the lake and valley has substantially increased theoutburst flood hazard.” Rupert F. Stuart-Smith et al., Increased Outburst Flood Hazard From Lake
Palcacocha Due to Human-Induced Glacier Retreat, 14 NATURE GEOSCIENCE 85, 85 (2021).
149. Peruvian Farmer Sues German Utility RWE over Dangers Related to Glacial Melting, supra note
147.
150. See Sarah Kaplan, A Melting Glacier, An Imperiled City and One Farmer’s Fight for Climate Justice,
WASH. POST (Aug. 28, 2022), https://www.washingtonpost.com/climate-environment/interactive/
2022/peru-climate-lawsuit-melting-glacier/(discussing the Palcacocha drainage project).
151. See id. (“The lawsuit asked the firm to pay roughly $20,000, about 0.47[%] of the cost of
the Palcacocha drainage project - commensurate with the company’s contribution to global
emissions.”).
152. See Lliuya Trial Court Decision, supra note 57 (noting the testimony of Dr. Huggel, who
testified as to the portion of anthropogenic climate change that has likely caused the melting of
the glaciers, and Professor Latif, whose testimony elaborated on how all GHGs contribute toglacial meltdown).
153. See Landgericht Essen [LG] [Regional Court of Essen] Dec. 15, 2016, Aktenzeichen 2 O
285/15 6-7, 2016.
154. See id.

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On appeal, the Higher Regional Court of Hamm disagreed andfound that emitters can be held responsible for damages caused by climate change.155 Because the parties disagreed about the facts and wereboth able to substantiate their allegations with scientific proof,156 theCourt decided to collect evidence on the facts presented by the plaintiff, including on (1) the imminent threat of a GLOF to the plaintiff’s
property, and (2) the causal chain leading from RWE’s emissions to
global warming and the melting of the glacier.157 To answer the firstquestion, two court-appointed experts,158 together with the judges andthe parties, visited the site in Peru in May 2022.159 Once the Court
resolves the question of whether the glacial melt is an imminent threat,
it will proceed to analyze the cause of that threat.

155. Oberlandesgericht Hamm [OLG] [Higher Regional Court of Hamm] Nov. 30, 2017,
Aktenzeichen I-5 U 15/17 [hereinafter Lliuya 2017 November Order].
156. The reliability of the proof offered by the parties varies. The court clearly distinguishes
between the scientific sources presented, valuing work prepared by experts independently fromthe proceedings or parties more highly than work that was commissioned by the parties. See Lliuya
2017 November Order, supra note 155. For example, a 2021 study that precisely analyzed thethreat of a GLOF to the city of Huaraz was considered very valuable because it had not beencommissioned by the plaintiff. See id. On the other hand, a study submitted by RWE was allegedly
indirectly funded by RWE, as was the satellite imagery that was used in preparing the study, giving
rise to doubts as to the study’s authors’ independence and impartiality. See id.; see also ‘Battle of
Science’ Rages Over Peru Glacier, SOURCEMATERIAL (June 3, 2022), https://www.source-material.
org/battle-of-science-rages-over-peru-glacier/.
157. See Lliuya 2017 November Order, supra note 155. The second question was further
divided into: a) the rise of RWE’s CO2-emissions into the atmosphere, where they accumulate tohigher concentration of greenhouse gases, b) the higher concentration of greenhouse gas
molecules in the atmosphere, which reduces the earth’s heat radiation and thus, leads to global
warming, c) because of local increases in the median temperature, the melting of the Palcaraju
glacier is accelerated, and the water volume of the Palcacocha lagoon is increasing to an extent
that cannot be held back by natural moraines, and d) RWE’s contribution to the causal chain ofa)-c) is measurable and amounts to 0.47% until today (or a percentage to be determined by theexpert). See id.
158. Dr. Rolf Katzenbach, professor at Technical University of Darmstadt, Germany, and Dr.
Johannes Hübl, professor at University of Natural Resources and Life Sciences, Vienna, Austria.
See Oberlandesgericht Hamm: Beweisaufnahme in Peru im Rechtsstreit Lliuya ./. RWE (June17, 2022), https://www.olg-hamm.nrw.de/behoerde/presse/pressemitteilung_archiv/archiv/
2022_Pressearchiv/19_22_PE_Beweisaufnahme-in-Peru-im-Rechtsstreit-Lliuya-___-RWE/index.
php.
159. See id. The submission of the expert report is expected in summer 2023. The plaintiff,
meanwhile, has moved to limit the second evidentiary questions to determining RWE’s
contribution to climate change, arguing that no serious doubt remains that GHG emissions cause
and exacerbate global (and local) warming. See Brief filed by plaintiffs on April 15, 2021, to the
Oberlandesgericht Hamm, Aktenzeichen I-5 U 15/17, at 19.

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WEATHERING THE STORM OF CLIMATE LITIGATIONThe Court emphasized that it was closely following the scientific discussion to the extent possible160 without having the appropriate expertise, but the evidentiary questions were not sufficiently answered inaccordance with the rules of a forensic procedure and German civil
procedure laws.161 The Court acknowledged that “a certain probability”
exists for the plaintiff’s assertions that RWE’s GHG emissions are partly
responsible for global warming.162 However, the Court noted that
RWE’s contribution to the melting of the specific glacier was “entirely
unclear.”163 As such, the 2021 Stuart-Smith study that linked retreat of
the Palcaraju glacier to human activity was not considered sufficientevidence.164
Regarding foreseeability or predictability, both elements of the legal
standard of causation, the Court found that global warming has been aforeseeable consequence of GHG emissions ever since Dr. Charles D.
Keeling began documenting atmospheric CO2 concentrations in 1958,
subsequently relating the increased concentrations to the greenhouseeffect.165 The year 1958 thus marked the starting point for evaluating
RWE’s contribution to climate change, because only since then could
RWE have known about the consequences of its actions.166

160. See Lliuya 2017 November Order, supra note 155 (citing to the study relating to retreat of
the Palcaraju glacier).
161. See Oberlandesgericht Hamm [OLG] [Higher Regional Court of Hamm] July 1, 2021,
Aktenzeichen I-5 U 15/17 [hereinafter Higher Regional Court of Hamm July 1, 2021].
162. See id. § I.
163. Id. (“völlig ungeklärt”).
164. See id. Arguably, considering that the highest judicial authority in Germany, the Federal
Constitutional Court, had articulated the scientific foundation of climate change in Neubauer, see
generally Neubauer, supra note 132, the Higher Regional Court of Hamm could rely, in part, on
those findings.
165. See Higher Regional Court of Hamm July 1, 2021, supra note 161, § II.4. Interestingly, thecourt considers this to be a fact known to the court which therefore does not require proof by theparties. See id. Yet, the court’s conclusion is interesting, considering that Keeling only started his
measurements and data collection on CO2 concentrations in 1958 but did not reach theconclusion of anthropogenic greenhouse effect until later. See Weart, supra note 12 (“Painstaking
measurements by C.D. Keeling drove home the point in 1960, showing that the level of the gas
was in fact rising, year by year.”). Having found that global warming as a consequence of GHG
emissions has been foreseeable since 1958 does not spare the plaintiff from proving that precisely
0.47% of climate change is caused by the defendant.
166. Oberlandesgericht Hamm [OLG] [Higher Regional Court of Hamm] Sept. 27, 2021,
Aktenzeichen I-31 U 46/21. RWE’s liability will depend on further elements of attribution of thecausal chain to acts by RWE and its legal predecessor. See id. The court is considering RWE’s
subsidiaries whose activities are initiated and controlled by RWE AG, and whose economic gain isrealized by RWE AG. See id.

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As these cases across a number of jurisdictions demonstrate, there isa developing theme of courts recognizing IPCC reports as the global
scientific consensus on climate change. Importantly, the recognition of
the IPCC as the world’s authoritative source of climate science can help
reduce chances of climate denial where climate change has become adivisive social and political issue.167 It can also facilitate faster court proceedings when scientific findings are largely undisputed (e.g., Julianaand Milieudefensie). Further, uncertainties around particular topics
addressed in IPCC reports do not reduce the value that scientific consensus has in climate litigation (e.g., Neubauer). Yet, other cases revealthat the attribution of certain impacts or events can still pose a serious
challenge to pro-climate parties, requiring years of collecting evidence
and preparing scientific reports (e.g., Lliuya). It is therefore importantthat scientists are able to communicate what they know when questions
arise in legal cases, and that judges understand the language of science
to appropriately assess the technical content brought before them.168
IV. PREPARING THE COURTS: CLIMATE SCIENCE EDUCATION FOR JUDGES
To make informed decisions on the many and varied cases about climate change that are being brought before the world’s courts, judges
will require a basic understanding of climate science and an awarenessof the rich landscape of scientifically reliable resources that are available to them. While this includes leveraging existing procedural tools
and resources,169 ongoing judicial education also plays an importantrole.170 In some instances, judges may be able to orchestrate training

167. For a discussion of climate polarization, see generally Riley E. Dunlap et al., The Political
Divide on Climate Change: Partisan Polarization Widens in the U.S., 58 ENV’T: SCI. & POL’Y FORSUSTAINABLE DEV. 4 (2016). But see Alec Tyson et al., What the Data Says About Americans’ Views of
Climate Change, PEW RSCH. CTR. (Aug. 9, 2023), https://www.pewresearch.org/short-reads/2023/
04/18/for-earth-day-key-facts-about-americans-views-of-climate-change-and-renewable-energy/(detailing opinion polls that reveal consensus from Americans on the need to address climatechange).
168. See Breyer, supra note 35, at 2 (stating that judicial “decisions should reflect a proper
scientific and technical understanding so that the law can respond to the needs of the public.”).
169. See, e.g., FED. JUDICIAL CTR. & NAT’L RSCH. COUNCIL, REFERENCE MANUAL ON SCIENTIFIC
EVIDENCE, at xv (3d ed. 2011) (providing a resource that assists judges in “manag[ing] cases
involving complex scientific and technical evidence” by “describ[ing] basic principles of major
scientific fields from which legal evidence is typically derived and provid[ing] examples of cases
in which such evidence [has been] used.”); see also ROBIN KUNDIS CRAIG, PROCEDURAL TECHNIQUESAVAILABLE FOR CLIMATE LITIGATION, CLIMATE SCIENCE AND LAW FOR JUDGES (2022).
170. Judicial education organizations and institutes exist in judiciaries throughout the world
to help ensure judges are properly trained, are aware of the latest developments in the law, andmaintain the ability to adequately adjudicate complex legal and factual disputes. Primary

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sessions in connection with a specific dispute. In 2018, one famous casebrought by the California cities of San Francisco and Oakland against
numerous oil companies, U.S. District Judge for the Northern Districtof California William Alsup ordered the parties to organize a tutorial
on climate science for him to learn about the issue.171 He even included
a list of eight specific questions to guide the parties’ presentations.172
While this approach to bridging the judicial and scientific knowledge
gap was a good example of creative judicial decision making, Judge
Alsup, and the efficiency of the legal process, would likely have benefitted from education about climate science prior to a case arriving on his
docket.
The Environmental Law Institute’s Climate Judiciary Project (CJP)
provides objective judicial-educational programming about climate science and how it is emerging in the law.173 CJP regularly collaborates
with judicial education organizations that provide broader programming,such as the National Judicial College and Federal Judicial Center.
Building on the Environmental Law Institute’s highly respected reputation for delivering bias-free judicial education programs, CJP works withleading scientists and legal scholars to educate judges with the basic science they need to adjudicate the climate litigation over which they preside.174 CJP has developed a thirteen-module “Climate Science and Law
for Judges” curriculum on important areas of climate science and related
legal topics.175 Operating outside the context of any specific case, thedomestic judicial educational entities are the Federal Judicial Center and the National Judicial
College in the United States, the Studiecentrum Rechtspleging (Training and Study Centre for
the Judiciary) in the Netherlands, and the Deutsche Richterakademie (German Judicial
Academy) in Germany. European judicial educational entities include the Academy of European
Law, and many entities have been consolidated in the European Judicial Training Network.
171. See Notice re Tutorial, People of the State of California v. BP P.L.C., No. 17-06012 (N.D.
Cal., Feb. 27, 2018), ECF No. 117. The two-part tutorial focused on “the history of scientific studyof climate change” and “the best science now available on global warming, glacier melt, sea rise,and coastal flooding.” Id.; See also Natasha Geiling, City of Oakland v. BP: Testing the Limits of Climate
Science in Climate Litigation, 46 ECOLOGY L.Q. 683, 684 (2019) (“the court ordered the first-everclimate science tutorial in climate litigation[.]”.
172. See Some Questions for the Tutorial, People of the State of California v. BP P.L.C., No. 1706011 (N.D. Cal., Mar. 6, 2018), ECF No. 138 (stating the questions as a follow up to the Notice reTutorial, supra note 171).
173. See About CJP, ENV’T L. INST.: CLIMATE JUDICIARY PROJECT, https://cjp.eli.org/about (lastvisited June 29, 2023).
174. See Sandra Nichols Thiam & Paul Hanle, Judging in a Changed Climate, 39 ENV’T FORUM 54,
59 (2022).
175. See Curriculum Summary, ENV’T L. INST.: CLIMATE JUDICIARY PROJECT, https://cjp.eli.org/
curriculum (last visited June 29, 2023) (science modules include topics such as How Climate
Science Works, What Is Causing Climate Change?, Climate Justice, among others, while legal

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effort also organizes various seminars and workshops that connect
judges with climate scientists, during which judges learn from and ask
questions to scientists about their areas of expertise.176 Because of thehigh quality of the content and a growing demand for more, these educational services enjoy a wide degree of support from the judicial, scientific, and legal scholarly communities.177
V. CONCLUSION
Judges in tribunals across the world are encountering cases involving
climate change. As impacts become increasingly dire, and climate science
continues to be refined, judges can be expected to deal with climate science in their courtrooms. Attribution science is likely to continue to playa central role. International tribunals may provide guidance on the obligations of states under numerous international law regimes, and indoing so, may consider specific climate science studies. Climate cases
from domestic jurisdictions in the United States, the Netherlands, andGermany, provide examples of the role that science has played. The
storm of cases is coming, and it is time to prepare.

topics include an overview and trends, government action, attribution science and tort litigation,
fundamental rights, procedural techniques, and remedies).
176. See Thiam & Hanle, supra note 174, at 58.
177. Id. at 59 (noting that “[s]ince its inauguration, [CJP] ha[s] attracted the support ofleading federal and state judges[.]”).

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